,transcriber's ,note3 ,the illustrations have been included with another version of this work4 ,the image files have been named in a straightforward manner that corresponds to the numbering in the text2 thus1 ,illustration #g is included as file fig#jjg4png1 while ,illustration 7,a7 #bb is included as file fig#jbb;a4png4 ,,the ,,radio ,,amateur',s ,,hand ,,book ,illustration3 ,a4 ,frederick ,collins1 ,inventor of the ,wireless ,telephone1 #ahii4 ,awarded ,gold ,medal for same1 ,alaska ,yukon ,pacific ,exposition1 #aiji4 ,,the ,,radio ,,amateur',s ,,hand ,,book ,a ,complete1 ,authentic and ,informative ,work on ,wireless ,telegraphy and ,telephony ,,by ,a4 ,,frederick ,,collins ,inventor of the ,wireless ,telephone #ahii2 ,historian of ,wireless #aija-aiaj2 ,author of ,wireless ,telegraphy #aije ,,to ,,william ,,marconi ,,inventor ,,of ,,the ,,wireless ,,telegraph ,,introduction ,before delving into the mysteries of receiving and sending messages without wires1 a word as to the history of the art and its present day applications may be of service4 ,while popular interest in the subject has gone forward by leaps and bounds within the last two or three years1 it has been a matter of scientific experiment for more than a quarter of a century4 ,the wireless telegraph was invented by ,william ,marconi1 at ,bologna1 ,italy1 in #ahif1 and in his first experiments he sent dot and dash signals to a distance of #bjj or #cjj feet4 ,the wireless telephone was invented by the author of this book at ,narberth1 ,penn41 in #ahii1 and in his first experiments the human voice was transmitted to a distance of three blocks4 ,the first vital experiments that led up to the invention of the wireless telegraph were made by ,heinrich ,hertz1 of ,germany1 in #ahhh when he showed that the spark of an induction coil set up electric oscillations in an open circuit1 and that the energy of these waves was1 in turn1 sent out in the form of electric waves4 ,he also showed how they could be received at a distance by means of a ring detector1 which he called a resonator ,in #ahij1 ,edward ,branly1 of ,france1 showed that metal filings in a tube cohered when electric waves acted on them1 and this device he termed a radio conductor2 this was improved upon by ,sir ,oliver ,lodge1 who called it a coherer4 ,in #ahie1 ,alexander ,popoff1 of ,russia1 constructed a receiving set for the study of atmospheric electricity1 and this arrangement was the earliest on record of the use of a detector connected with an aerial and the earth4 ,marconi was the first to connect an aerial to one side of a spark gap and a ground to the other side of it4 ,he used an induction coil to energize the spark gap1 and a telegraph key in the primary circuit to break up the current into signals4 ,adding a ,morse register1 which printed the dot and dash messages on a tape1 to the ,popoff receptor he produced the first system for sending and receiving wireless telegraph messages4 ,illustration3 ,collins' ,wireless ,telephone ,exhibited at the ,madison ,square ,garden1 ,october #aijh4 ,after ,marconi had shown the world how to telegraph without connecting wires it would seem1 on first thought1 to be an easy matter to telephone without wires1 but not so1 for the electric spark sets up damped and periodic oscillations and these cannot be used for transmitting speech4 ,instead1 the oscillations must be of constant amplitude and continuous4 ,that a direct current arc light transforms a part of its energy into electric oscillations was shown by ,firth and ,rogers1 of ,england1 in #ahic4 ,the author was the first to connect an arc lamp with an aerial and a ground1 and to use a microphone transmitter to modulate the sustained oscillations so set up4 ,the receiving apparatus consisted of a variable contact1 known as a pill-box detector1 which ,sir ,oliver ,lodge had devised1 and to this was connected an ,ericsson telephone receiver1 then the most sensitive made4 ,a later improvement for setting up sustained oscillations was the author's rotating oscillation arc4 ,since those memorable days of more than two decades ago1 wonderful advances have been made in both of these methods of transmitting intelligence1 and the end is as yet nowhere in sight4 ,twelve or fifteen years ago the boys began to get fun out of listening-in to what the ship and shore stations were sending and1 further1 they began to do a little sending on their own account4 ,these youngsters1 who caused the professional operators many a pang1 were the first wireless amateurs1 and among them experts were developed who are foremost in the practice of the art today4 ,away back there1 the spark coil and the arc lamp were the only known means for setting up oscillations at the sending end1 while the electrolytic and crystal detectors were the only available means for the amateur to receive them4 ,as it was next to impossible for a boy to get a current having a high enough voltage for operating an oscillation arc lamp1 wireless telephony was out of the question for him1 so he had to stick to the spark coil transmitter which needed only a battery current to energize it1 and this1 of course1 limited him to sending ,morse signals4 ,as the electrolytic detector was cumbersome and required a liquid1 the crystal detector which came into being shortly after was just as sensitive and soon displaced the former1 even as this had displaced the coherer4 ,a few years ahead of these amateurs1 that is to say in #aije1 ,j4 ,a4 ,fleming1 of ,england1 invented the vacuum tube detector1 but ten more years elapsed before it was perfected to a point where it could compete with the crystal detector4 ,then its use became general and workers everywhere sought to1 and did improve it4 ,further1 they found that the vacuum tube would not only act as a detector1 but that if energized by a direct current of high voltage it would set up sustained oscillations like the arc lamp1 and the value of sustained oscillations for wireless telegraphy as well as wireless telephony had already been discovered4 ,the fact that the vacuum tube oscillator requires no adjustment of its elements1 that its initial cost is much less than the oscillation arc1 besides other considerations1 is the reason that it popularized wireless telephony2 and because continuous waves have many advantages over periodic oscillations is the reason the vacuum tube oscillator is replacing the spark coil as a wireless telegraph transmitter4 ,moreover1 by using a number of large tubes in parallel1 powerful oscillations can be set up and1 hence1 the waves sent out are radiated to enormous distances4 ,while oscillator tubes were being experimented with in the research laboratories of the ,general ,electric1 the ,westinghouse1 the ,radio ,corporation of ,america1 and other big companies1 all the youthful amateurs in the country had learned that by using a vacuum tube as a detector they could easily get messages #ejj miles away4 ,the use of these tubes as amplifiers also made it possible to employ a loud speaker1 so that a room1 a hall1 or an out-of-door audience could hear clearly and distinctly everything that was being sent out4 ,the boy amateur had only to let father or mother listen-in1 and they were duly impressed when he told them they were getting it from ,,kdka 7the ,pittsburgh station of the ,westinghouse ,co471 for was not ,pittsburgh #ejj miles away6 ,and so they1 too1 became enthusiastic wireless amateurs4 ,this new interest of the grown-ups was at once met not only by the manufacturers of apparatus with complete receiving and sending sets1 but also by the big companies which began broadcasting regular programs consisting of music and talks on all sorts of interesting subjects4 ,this is the wireless1 or radio1 as the average amateur knows it today4 ,but it is by no means the limit of its possibilities4 ,on the contrary1 we are just beginning to realize what it may mean to the human race4 ,the ,government is now utilizing it to send out weather1 crop and market reports4 ,foreign trade conditions are being reported4 ,the ,naval ,observatory at ,arlington is wirelessing time signals4 ,department stores are beginning to issue programs and advertise by radio6 ,cities are also taking up such programs1 and they will doubtless be included soon among the regular privileges of the tax-payers4 ,politicians address their constituents4 ,preachers reach the stay-at-homes4 ,great singers thrill thousands instead of hundreds4 ,soon it will be possible to hear the finest musical programs1 entertainers1 and orators1 without budging from one's easy chair4 ,in the ,world ,war wireless proved of inestimable value4 ,airplanes1 instead of flying aimlessly1 kept in constant touch with headquarters4 ,bodies of troops moved alertly and intelligently4 ,ships at sea talked freely1 over hundreds of miles4 ,scouts reported4 ,everywhere its invisible aid was invoked4 ,in time of peace1 however1 it has proved and will prove the greatest servant of mankind4 ,wireless messages now go daily from continent to continent1 and soon will go around the world with the same facility4 ,ships in distress at sea can summon aid4 ,vessels everywhere get the day's news1 even to baseball scores4 ,daily new tasks are being assigned this tireless1 wireless messenger4 ,messages have been sent and received by moving trains1 the ,lackawanna and the ,rock ,island railroads being pioneers in this field4 ,messages have also been received by automobiles1 and one inventor has successfully demonstrated a motor car controlled entirely by wireless4 ,this method of communication is being employed more and more by newspapers4 ,it is also of great service in reporting forest fires4 ,colleges are beginning to take up the subject1 some of the first being ,tufts ,college1 ,hunter ,college1 ,princeton1 ,yale1 ,harvard1 and ,columbia1 which have regularly organized departments for students in wireless4 ,instead of the unwieldy and formidable looking apparatus of a short time ago1 experimenters are now vying with each other in making small or novel equipment4 ,portable sets of all sorts are being fashioned1 from one which will go into an ordinary suitcase1 to one so small it will easily slip into a ,brownie camera4 ,one receiver depicted in a newspaper was one inch square6 ,another was a ring for the finger1 with a setting one inch by five-eighths of an inch1 and an umbrella as a ground4 ,walking sets with receivers fastened to one's belt are also common4 ,daily new novelties and marvels are announced4 ,meanwhile1 the radio amateur to whom this book is addressed may have his share in the joys of wireless4 ,to get all of these good things out of the ether one does not need a rod or a gun--only a copper wire made fast at either end and a receiving set of some kind4 ,if you are a sheer beginner1 then you must be very careful in buying your apparatus1 for since the great wave of popularity has washed wireless into the hearts of the people1 numerous companies have sprung up and some of these are selling the veriest kinds of junk4 ,and how1 you may ask1 are you going to be able to know the good from the indifferent and bad sets8 ,by buying a make of a firm with an established reputation4 ,i have given a few offhand at the end of this book4 ,obviously there are many others of merit--so many1 indeed1 that it would be quite impossible to get them all in such a list1 but these will serve as a guide until you can choose intelligently for yourself4 ,a4 ,f4 ,c4 ,,contents ,,chapter ,i4 ,,how ,,to ,,begin ,,wireless ,kinds of ,wireless ,systems--,parts of a ,wireless ,system--,the ,easiest ,way to ,start--,about ,aerial ,wire ,systems--,about the ,receiving ,apparatus--,about ,transmitting ,stations--,kinds of ,transmitters--,the ,spark ,gap ,wireless ,telegraph ,transmitter--,the ,vacuum ,table ,telegraph ,transmitter--,the ,wireless ,telephone ,transmitter4 ,,ii4 ,,putting ,,up ,,your ,,aerial ,kinds of ,aerial ,wire ,systems--,how to ,put ,up a ,cheap ,receiving ,aerial--,a ,two-wire ,aerial--,connecting in the ,ground--,how to ,put up a ,good ,aerial--,an ,inexpensive ,good ,aerial--,the ,best ,aerial ,that ,can be ,made--,assembling the ,aerial--,making a ,good ,ground4 ,,iii4 ,,simple ,,telegraph ,,and ,,telephone ,,receiving ,,sets ,assembled ,wireless ,receiving ,sets--,assembling ,your ,own ,receiving ,set--,the ,crystal ,detector--,the ,tuning ,coil--,the ,loose ,coupled ,tuning ,coil--,fixed and ,variable ,condensers--,about ,telephone ,receivers-- ,connecting ,up the ,parts--,receiving ,set ,no4 #b--;,adjusting the ,no4 #a ,set--,the ,tuning ,coil--,adjusting the ,no4 #b ,set4 ,,iv4 ,,simple ,,telegraph ,,sending ,,sets ,a ,cheap ,transmitting ,set 7,no4 #a7--,the ,spark ,coil--,the ,battery--,the ,telegraph ,key--,the ,spark ,gap--,the ,tuning ,coil--,the ,high-tension ,condenser--,a ,better ,transmitting ,set 7,no4 #b7--,the ,alternating ,current ,transformer--,the ,wireless ,key--,the ,spark ,gap--,the ,high-tension ,condenser--,the ,oscillation ,transformer--,connecting ,up the ,apparatus--,for ,direct ,current--,how to ,adjust ,your ,transmitter4 ,tuning ,with a ,hot ,wire ,ammeter--,to ,send ,out a #bjj-meter ,wave ,length--,the ,use of the ,aerial ,switch--,aerial ,switch for a ,complete ,sending and ,receiving ,set--,connecting in the ,lightning ,switch4 ,v4 ,,electricity ,,simply ,,explained ,electricity at ,rest and in ,motion--,the ,electric ,current and its ,circuit--,current and the ,ampere--,resistance and the ,ohm--,what ,ohm's ,law ,is--,what the ,watt and ,kilowatt ,are--,electromagnetic ,induction--,mutual ,induction--,high-frequency ,currents--,constants of an ,oscillation ,circuit--,what ,capacitance ,is--,what ,inductance ,is--,what ,resistance ,is--,the ,effect of ,capacitance4 ,,vi4 ,,how ,,the ,,transmitting ,,and ,,receiving ,,sets ,,work ,how ,transmitting ,set ,no4 #a ,works--,the ,battery and ,spark ,coil ,circuit--,changing the ,primary ,spark ,coil ,current ,into ,secondary ,currents--,what ,ratio of ,transformation ,means--,the ,secondary ,spark ,coil ,circuit--,the ,closed ,oscillation ,circuit--,how ,transmitting ,set ,no4 #b ,works--,with ,alternating ,current--,with ,direct ,current--,the ,rotary ,spark ,gap--,the ,quenched ,spark ,gap--,the ,oscillation ,transformer--,how ,receiving ,set ,no4 #a ,works--,how ,receiving ,set ,no4 #b ,works4 ,,vii4 ,,mechanical ,,and ,,electrical ,,tuning ,damped and ,sustained ,mechanical ,vibrations--,damped and ,sustained ,oscillations--,about ,mechanical ,tuning--,about ,electric ,tuning4 ,,viii4 ,a ,,simple ,,vacuum ,,tube ,,detector ,,receiving ,,set ,assembled ,vacuum ,tube ,receiving ,set--,a ,simple ,vacuum ,tube ,receiving ,set--,the ,vacuum ,tube ,detector--,three ,electrode ,vacuum ,tube ,detector--,the ,dry ,cell and ,storage ,batteries--,the ,filament ,rheostat--,assembling the ,parts--,connecting ,up the ,parts--,adjusting the ,vacuum ,tube ,detector ,receiving ,set4 ,,ix4 ,,vacuum ,,tube ,,amplifier ,,receiving ,,sets ,a ,grid ,leak ,amplifier ,receiving ,set4 ,with ,crystal ,detector--,the ,fixed ,resistance ,unit1 or ,grid ,leak--,assembling the ,parts for a ,crystal ,detector ,set--,connecting up the ,parts for a ,crystal ,detector--,a ,grid ,leak ,amplifying ,receiving ,set ,with ,vacuum ,tube ,detector--,a ,radio ,frequency ,transformer ,amplifying ,receiving ,set--,an ,audio ,frequency ,transformer ,amplifying ,receiving ,set--,a ,six ,step ,amplifier ,receiving ,set with a ,loop ,aerial--,how to ,prevent ,howling4 ,x4 ,,regenerative ,,amplification ,,receiving ,,sets ,the ,simplest ,type of ,regenerative ,receiving ,set--,with ,loose ,coupled ,tuning ,coil--,connecting ,up the ,parts--,an ,efficient ,regenerative ,receiving ,set4 ,with ,three ,coil ,loose ,coupler--,the ,a ,battery ,potentiometer--,the ,parts and ,how to ,connect ,them ,up--,a ,regenerative ,audio ,frequency ,amplifier--,the ,parts and ,how to ,connect ,them ,up4 ,,xi4 ,,short ,,wave ,,regenerative ,,receiving ,,sets ,a ,short ,wave ,regenerative ,receiver1 with ,one ,variometer and ,three ,variable ,condensers--,the ,variocoupler--,the ,variometer--,connecting ,up the ,parts--,short ,wave ,regenerative ,receiver with ,two ,variometers and ,two ,variable ,condensers--,the ,parts and ,how to ,connect ,them ,up4 ,,xii4 ,,intermediate ,,and ,,long ,,wave ,,regenerative ,,receiving ,,sets ,intermediate ,wave ,receiving ,sets--,intermediate ,wave ,set ,with ,loading ,coils--,the ,parts and ,how to ,connect ,them ,up--,an ,intermediate ,wave ,set with ,variocoupler ,inductance ,coils--,the ,parts and ,how to ,connect ,them ,up--,a ,long ,wave ,receiving ,set--,the ,parts and ,how to ,connect ,them ,up4 ,,xiii4 ,,heterodyne ,,or ,,beat ,,long ,,wave ,,telegraph ,,receiving ,,set ,what the ,heterodyne or ,beat ,method ,is--,the ,autodyne or ,self-heterodyne ,long ,wave ,receiving ,set--,the ,parts and ,connections of an ,autodyne or ,self-heterodyne1 ,receiving ,set--,the ,separate ,heterodyne ,long ,wave ,receiving ,set--,the ,parts and ,connections of a ,separate ,heterodyne ,long ,wave ,receiving ,set4 ,,xiv4 ,,headphones ,,and ,,loud ,,speakers ,wireless ,headphones--,how a ,bell ,telephone ,receiver is ,made--,how a ,wireless ,headphone is ,made--,about ,resistance1 ,turns of ,wire and ,sensitivity of ,headphones--,the ,impedance of ,headphones--,how the ,headphones ,work--,about ,loud ,speakers--,the ,simplest ,type of ,loud ,speaker--,another ,simple ,kind of ,loud ,speaker--,a ,third ,kind of ,simple ,loud ,speaker--,a ,super ,loud ,speaker4 ,,xv4 ,,operation ,,of ,,vacuum ,,tube ,,receptors ,what is ,meant by ,ionization--,how ,electrons are ,separated from ,atoms--,action of the ,two ,electrode ,vacuum ,tube--,how the ,two ,electrode ,tube ,acts as a ,detector--,how the ,three ,electrode ,tube ,acts as a ,detector--,how the ,vacuum ,tube ,acts as an ,amplifier--,the ,operation of a ,simple ,vacuum ,tube ,receiving ,set--,operation of a ,regenerative ,vacuum ,tube ,receiving ,set--,operation of ,autodyne and ,heterodyne ,receiving ,sets--,the ,autodyne1 or ,self-,heterodyne ,receiving ,set--,the ,separate ,heterodyne ,receiving ,set4 ,,xvi4 ,,continuous ,,wave ,,telegraph ,,transmitting ,,sets ,,with ,,direct ,,current ,sources of ,current for ,telegraph ,transmitting ,sets--,an ,experimental ,continuous ,wave ,telegraph ,transmitter--,the ,apparatus ,you ,need--,the ,tuning ,coil--,the ,condensers--,the ,aerial ,ammeter--,the ,buzzer and ,dry ,cell--,the ,telegraph ,key--,the ,vacuum ,tube ,oscillator--,the ,storage ,battery--,the ,battery ,rheostat--,the ,oscillation ,choke ,coil--,transmitter ,connectors--,the ,panel ,cutout--,connecting ,up the ,transmitting ,apparatus--,a #ajj-mile ,c4 ,w4 ,telegraph ,transmitter--,the ,apparatus ,you ,need--,the ,tuning ,coil--,the ,aerial ,condenser--,the ,aerial ,ammeter--,the ,grid and ,blocking ,condensers--,the ,key ,circuit ,apparatus--,the #e ,watt ,oscillator ,vacuum ,tube--,the ,storage ,battery and ,rheostat--,the ,filament ,voltmeter--,the ,oscillation ,choke ,coil--,the ,motor-generator ,set--,the ,panel ,cut-out--,the ,protective ,condenser--,connecting ,up the ,transmitting ,apparatus--,a #bjj-mile ,c4 ,w4 ,telegraph ,transmitter--,a #ejj-mile ,c4 ,w4 ,telegraph ,transmitter--,the ,apparatus and ,connections-- ,the #ej-watt ,vacuum ,tube ,oscillator--,the ,aerial ,ammeter--,the ,grid ,leak ,resistance--,the ,oscillation ,choke ,coil--,the ,filament ,rheostat--,the ,filament ,storage ,battery--,the ,protective ,condenser--,the ,motor-generator--,a #ajjj-mile ,c4 ,w4 ,telegraph ,transmitter4 ,,xvii4 ,,continuous ,,wave ,,telegraph ,,transmitting ,,sets ,,with ,,alternating ,,current ,a #ajj-mile ,c4 ,w4 ,telegraph ,transmitting ,set--,the ,apparatus ,required--,the ,choke ,coils--,the ,milli-ammeter--,the ,a4 ,c4 ,power ,transformer--,connecting ,up the ,apparatus--,a #bjj- to #ejj-mile ,c4 ,w4 ,telegraph ,transmitting ,set-,a #ejj- to #ajjj-mile ,c4 ,w4 ,telegraph ,transmitting ,set--,the ,apparatus ,required--,the ,alternating ,current ,power ,transformer-,connecting ,up the ,apparatus4 ,,xviii4 ,,wireless ,,telephone ,,transmitting ,,sets ,,with ,,direct ,,and ,,alternating ,,currents ,a ,short ,distance ,wireless ,telephone ,transmitting ,set--,with #aaj-volt ,direct ,lighting ,current--,the ,apparatus ,you ,need--,the ,microphone ,transmitter--,connecting ,up the ,apparatus--,a #be- to #ej-mile ,wireless ,telephone ,transmitter--,with ,direct ,current ,motor ,generator--,the ,apparatus ,you ,need--,the ,telephone ,induction ,coil--,the ,microphone ,transformer--,the ,magnetic ,modulator--,how the ,apparatus is ,connected ,up--,a #ej- to #ajj-mile ,wireless ,telephone ,transmitter--,with ,direct ,current ,motor ,generator--,the ,oscillation ,choke ,coil--,the ,plate and ,grid ,circuit ,reactance ,coils--,connecting up the ,apparatus--,a #ajj- to #bjj-mile ,wireless ,telephone ,transmitter--,with ,direct ,current ,motor ,generator--,a #ej- to #ajj-mile ,wireless ,telephone ,transmitting ,set--,with #ajj-volt ,alternating ,current--,the ,apparatus ,you ,need--,the ,vacuum ,tube ,rectifier--,the ,filter ,condensers--,the ,filter ,reactance ,coil-- ,connecting ,up the ,apparatus--,a #ajj- to #bjj-mile ,wireless ,telephone ,transmitting ,set--,with #aaj-volt ,alternating ,current--,apparatus ,required4 ,,xix4 ,,the ,,operation ,,of ,,vacuum ,,tube ,,transmitters ,the ,operation of the ,vacuum ,tube ,oscillator--,the ,operation of ,c4 ,w4 ,telegraph ,transmitters with ,direct ,current--,short ,distance ,c4 ,w4 ,transmitter--,the ,operation of the ,key ,circuit--,the ,operation of ,c4 ,w4 ,telegraph ,transmitting with ,direct ,current--,the ,operation of ,c4 ,w4 ,telegraph ,transmitters with ,alternating ,current--,with a ,single ,oscillator ,tube--,heating the ,filament with ,alternating ,current--,the ,operation of ,c4 ,w4 ,telegraph ,transmitters with ,alternating ,current-- ,with ,two ,oscillator ,tubes--,the ,operation of ,wireless ,telephone ,transmitters with ,direct ,current--,short ,distance ,transmitter--,the ,microphone ,transmitter--,the ,operation of ,wireless ,telephone ,transmitters with ,direct ,current--,long ,distance ,transmitters--,the ,operation of ,microphone ,modulators--,the ,induction ,coil--,the ,microphone ,transformer--,the ,magnetic ,modulator--,operation of the ,vacuum ,tube as a ,modulator--,the ,operation of ,wireless ,telephone ,transmitters with ,alternating ,current--,the ,operation of ,rectifier ,vacuum ,tubes--,the ,operation of ,reactors and ,condensers4 ,,xx4 ,,how ,,to ,,make ,a ,,receiving ,,set ,,for #e4jj ,,or ,,less4 ,the ,crystal ,detector--,the ,tuning ,coil--,the ,headphone--,how to ,mount the ,parts--,the ,condenser--,how to ,connect ,up the ,receptor4 ,,appendix ,useful ,information--,glossary--,wireless ,don'ts4 ,,list ,,of ,,figures ,fig4 #a4--,simple ,receiving ,set ,fig4 #b4--,simple ,transmitting ,set 7,a7 ,fig4 #c4--;,flat ,top1 or ,horizontal ,aerial 7,b7 ,fig4 #c4--;,inclined ,aerial 7,a7 ,fig4 #d4--;,inverted ,l ,aerial 7,b7 ,fig4 #d--,t ,aerial ,fig4 #e4--,material for a ,simple ,aerial ,wire ,system 7,a7 ,fig4 #f4--,single ,wire ,aerial for ,receiving 7,b7 ,fig4 #f4--,receiving ,aerial with ,spark ,gap ,lightning ,arrester 7,c7 ,fig4 #f4--;,aerial with ,lightning ,switch ,fig4 #g4--,two-wire ,aerial 7,a7 ,fig4 #h4--,part of a ,good ,aerial 7,b7 ,fig4 #h4--,the ,spreaders 7,a7 ,fig4 #i4--,the ,middle ,spreader 7,b7 ,fig4 #i4--,one ,end of ,aerial ,complete 7,c7 ,fig4 #i4--,the ,leading in ,spreader 7,a7 ,fig4 #aj4--;,cross ,section of ,crystal ,detector 7,b7 ,fig4 #aj4--,the ,crystal ,detector ,complete 7,a7 ,fig4 #aa4--,schematic ,diagram of a ,double ,slide ,tuning ,coil 7,b7 ,fig4 #aa4--;,double ,slide ,tuning ,coil ,complete 7,a7 ,fig4 #ab4--,schematic ,diagram of a ,loose ,coupler 7,b7 ,fig4 #ab4--,loose ,coupler ,complete 7,a7 ,fig4 #ac4--;,how a ,fixed ,receiving ,condenser is ,built up 7,b7 ,fig4 #ac4--,the ,fixed ,condenser ,complete 7,c7 and 7,d7 ,fig4 #ac4--,variable ,rotary ,condenser ,fig4 #ad4--,pair of ,wireless ,headphones 7,a7 ,fig4 #ae4--,top ,view of ,apparatus ,layout for ,receiving ,set ,no4 #a 7,b7 ,fig4 #ae4--,wiring ,diagram for ,receiving ,set ,no4 #a 7,a7 ,fig4 #af4--,top ,view of ,apparatus ,layout for ,receiving ,set ,no4 #b 7,b7 ,fig4 #af4--,wiring ,diagram for ,receiving ,set ,no4 #b ,fig4 #ag4--;,adjusting the ,receiving ,set 7,a7 and 7,b7 ,fig4 #ah4--,types of ,spark ,coils for ,set ,no4 #a 7,c7 ,fig4 #ah4--,wiring ,diagram of ,spark ,coil ,fig4 #ai4--,other ,parts for ,transmitting ,set ,no4 #a 7,a7 ,fig4 #bj4--,top ,view of ,apparatus ,layout for ,sending ,set ,no4 #a 7,b7 ,fig4 #bj4--,wiring of ,diagram for ,sending ,set ,no4 #a ,fig4 #ba4--,parts for ,transmitting ,set ,no4 #b 7,a7 ,fig4 #bb4--,top ,view of ,apparatus ,layout for ,sending ,set ,no4 #b 7,b7 ,fig4 #bb4--,wiring ,diagram for ,sending ,set ,no4 #b ,fig4 #bc4--,using a #aaj-volt ,direct ,current with an ,alternating current ,transformer ,fig4 #bd4--,principle of the ,hot ,wire ,ammeter ,fig4 #be4--,kinds of ,aerial ,switches ,fig4 #bf4--,wiring ,diagram for a ,complete ,sending and ,receiving ,set ,no4 #a ,fig4 #bg4--,wiring ,diagram for ,complete ,sending and ,receiving ,set ,no4 #b ,fig4 #bh4--,water ,analogue for ,electric ,pressure ,fig4 #bi4--,water ,analogues for ,direct and ,alternating ,currents ,fig4 #cj4--;,how the ,ammeter and ,voltmeter are ,used ,fig4 #ca4--,water ,valve ,analogue of ,electric ,resistance 7,a7 and 7,b7 ,fig4 #cb4--;,how an ,electric ,current is ,changed into ,magnetic ,lines of ,force and ,these into an ,electric ,current 7,c7 and 7,d7 ,fig4 #cb4--;,how an ,electric ,current ,sets up a ,magnetic ,field ,fig4 #cc4--,the ,effect of ,resistance on the ,discharge of an ,electric ,current ,fig4 #cd4--;,damped and ,sustained ,mechanical ,vibrations ,fig4 #ce4--;,damped and ,sustained ,electric ,oscillations ,fig4 #cf4--,sound ,wave and ,electric ,wave ,tuned ,senders and ,receptors ,fig4 #cg4--,two ,electrode ,vacuum ,tube ,detectors ,fig4 #ch4--,three ,electrode ,vacuum ,tube ,detector and ,battery ,connections ,fig4 #ci4--;,a and ,b ,batteries for ,vacuum ,tube ,detectors ,fig4 #dj4--,rheostat for the ,a or ,storage-battery ,current 7,a7 ,fig4 #da4--,top ,view of ,apparatus ,layout for ,vacuum ,tube ,detector ,receiving ,set 7,b7 ,fig4 #da4--,wiring ,diagram of a ,simple ,vacuum ,tube ,receiving ,set ,fig4 #db4--;,grid ,leaks and ,how to ,connect them ,up ,fig4 #dc4--;,crystal ,detector ,receiving ,set with ,vacuum ,tube ,amplifier 7,resistance ,coupled7 7,a7 ,fig4 #dd4--,vacuum ,tube ,detector ,receiving ,set with ,one ,step ,amplifier 7,resistance ,coupled7 7,b7 ,fig4 #dd4--,wiring ,diagram for ,using ,one ,a or ,storage ,battery with an ,amplifier and a ,detector ,tube 7,a7 ,fig4 #de4--,wiring ,diagram for ,radio ,frequency ,transformer ,amplifying ,receiving ,set 7,b7 ,fig4 #de4--,radio ,frequency ,transformer 7,a7 ,fig4 #df4--;,audio ,frequency ,transformer 7,b7 ,fig4 #df4--,wiring ,diagram for ,audio ,frequency ,transformer ,amplifying ,receiving ,set4 7,with ,vacuum ,tube ,detector and ,two ,step ,amplifier ,tubes7 7,a7 ,fig4 #dg4--,six ,step ,amplifier with ,loop ,aerial 7,b7 ,fig4 #dg4--;,efficient ,regenerative ,receiving ,set 7,with ,three ,coil ,loose ,coupler ,tuner7 ,fig4 #dh4--,simple ,regenerative ,receiving ,set 7,with ,loose ,coupler ,tuner7 7,a7 ,fig4 #di4--;,diagram of ,three ,coil ,loose ,coupler 7,b7 ,fig4 #di4--,three ,coil ,loose ,coupler ,tuner ,fig4 #ej4--;,honeycomb ,inductance ,coil ,fig4 #ea4--,the ,use of the ,potentiometer ,fig4 #eb4--,regenerative ,audio ,frequency ,amplifier ,receiving ,set ,fig4 #ec4--;,how the ,vario ,coupler is ,made and ,works ,fig4 #ed4--;,how the ,variometer is ,made and ,works ,fig4 #ee4--,short ,wave ,regenerative ,receiving ,set 7,one ,variometer and ,three ,variable ,condensers7 ,fig4 #ef4--,short ,wave ,regenerative ,receiving ,set 7,two ,variometer and ,two ,variable ,condensers7 ,fig4 #eg4--,wiring ,diagram ,showing ,fixed ,loading ,coils for ,intermediate ,wave ,set ,fig4 #eh4--,wiring ,digram of ,intermediate ,wave ,receptor with ,one ,vario ,coupler and #ab ,section ,bank-wound ,inductance ,coil ,fig4 #ei4--,wiring ,diagram ,showing ,long ,wave ,receptor with ,vario ,couplers and #h ,bank-wound ,inductance ,coils ,fig4 #fj4--,wiring ,diagram of ,long ,wave ,autodyne1 or ,self-heterodyne ,receptor 7,compare with ,fig4 #gg7 ,fig4 #fa4--,wiring ,diagram of ,long ,wave ,separate ,heterodyne ,receiving ,set ,fig4 #fb4--;,cross ,section of ,bell ,telephone ,receiver ,fig4 #fc4--;,cross ,section of ,wireless ,headphone ,fig4 #fd4--,the ,wireless ,headphone ,fig4 #fe4--;,arkay ,loud ,speaker ,fig4 #ff4--;,amplitone ,loud ,speaker ,fig4 #fg4--;,amplitron ,loud ,speaker ,fig4 #fh4--,magnavox ,loud ,speaker ,fig4 #fi4--,schematic ,diagram of an ,atom ,fig4 #gj4--;,action of ,two-electrode ,vacuum ,tube 7,a7 and 7,b7 ,fig4 #ga4--;,how a ,two-electrode ,tube ,acts as ,relay or a ,detector 7,c7 ,fig4 #ga--,only the ,positive ,part of ,oscillations ,goes through the ,tube 7,a7 and 7,b7 ,fig4 #gb4--;,how the ,positive and ,negative ,voltages of the ,oscillations ,act on the ,electrons 7,c7 ,fig4 #gb4--;,how the ,three-electrode ,tube ,acts as ,detector and ,amplifier 7,d7 ,fig4 #gb4--;,how the ,oscillations ,control the ,flow of the ,battery ,current through the ,tube ,fig4 #gc4--;,how the ,heterodyne ,receptor ,works ,fig4 #gd4--,separate ,heterodyne ,oscillator 7,a7 ,fig4 #ge4--;,apparatus for ,experimental ,c4 ,w4 ,telegraph ,transmitter4 7,b7 ,fig4 #ge4--;,apparatus for ,experimental ,c4 ,w4 ,telegraph ,transmitter4 ,fig4 #gf4--;,experimental ,c4 ,w4 ,telegraph ,transmitter ,fig4 #gg--;,apparatus of #ajj-mile ,c4 ,w4 ,telegraph ,transmitter ,fig4 #gh4--e- to #ej-watt ,c4 ,w4 ,telegraph ,transmitter 7with a ,single ,oscillation ,tube7 ,fig4 #gi4--bjj-mile ,c4 ,w4 ,telegraph ,transmitter 7with ,two ,tubes in ,parallel7 ,fig4 #hj4--ej-watt ,oscillator ,vacuum ,tube ,fig4 #ha4--;,alternating ,current ,power ,transformer 7for ,c4 ,w4 ,telegraphy and ,wireless ,telephony7 ,fig4 #hb4--,wiring ,diagram for #bjj- to #ejj-mile ,c4 ,w4 ,telegraph ,transmitting ,set4 7,with ,alternating ,current47 ,fig4 #hc--,wiring ,diagram for #ejj- to #ajjj-mile ,c4 ,w4 ,telegraph ,transmitter ,fig4 #hd4--,standard ,microphone ,transmitter ,fig4 #he4--,wiring ,diagram of ,short ,distance ,wireless ,telephone ,set4 7,microphone in ,aerial ,wire47 ,fig4 #hf4--,telephone ,induction ,coil 7used with ,microphone ,transmitter74 ,fig4 #hg4--,microphone ,transformer ,used with ,microphone ,transmitter ,fig4 #hh4--,magnetic ,modulator ,used with ,microphone ,transmitter 7,a7 ,fig4 #hi4--,wiring ,diagram of #be--to #ej-mile ,wireless ,telephone4 7,microphone ,modulator ,shunted ,around ,grid-leak ,condenser7 7,b7 ,fig4 #hi4--,microphone ,modulator ,connected in ,aerial ,wire ,fig4 #ij4--,wiring ,diagram of #ej- to #ajj-mile ,wireless ,telephone ,transmitting ,set ,fig4 #ia4--,plate and ,grid ,circuit ,reactor ,fig4 #ib4--;,filter ,reactor for ,smoothing ,out ,rectified ,currents ,fig4 #ic4--ajj- to #bjj-mile ,wireless ,telephone ,transmitter 7,a7 and 7,b7 ,fig4 #id4--,operation of ,vacuum ,tube ,oscillators 7,c7 ,fig4 #id4--;,how a ,direct ,current ,sets up ,oscillations ,fig4 #ie4--,positive ,voltage ,only ,sets up ,oscillations ,fig4 #if4--,rasco ,baby ,crystal ,detector ,fig4 #ig4--;,how the ,tuning ,coil is ,made ,fig4 #ih4--,mesco loop-ohm ,head ,set ,fig4 #ii4--,schematic ,layout of the #e4jj ,receiving ,set ,fig4 #ajj4--,wiring ,diagram for the #e4jj ,receiving ,set ,,list ,,of ,,illustrations ,a4 ,frederick ,collins1 ,inventor of the ,wireless ,telephone1 #ahii4 ,awarded ,gold ,medal for same1 ,alaska ,yukon ,pacific ,exposition1 #aiji ,collins' ,wireless ,telephone ,exhibited at the ,madison ,square ,garden1 ,october1 #aijh ,general ,pershing ,listening-in ,the ,world's ,largest ,radio ,receiving ,station4 ,owned by the ,radio ,corporation of ,america at ,rocky ,point near ,port ,jefferson1 ,l4 ,i4 ,first ,wireless ,college in the ,world1 at ,tufts ,college1 ,mass ,alexander ,graham ,bell1 ,inventor of the ,telephone1 now an ardent ,radio ,enthusiast ,world's ,largest ,loud ,speaker ever made4 ,installed in ,lytle ,park1 ,cincinnati1 ,ohio1 to permit ,president ,harding's ,address at ,point ,pleasant1 ,ohio1 during the ,grant ,centenary ,celebration to be heard within a radius of one square ,united ,states ,naval ,high ,power ,station1 ,arlington1 ,va4 ,general view of ,power ,room4 ,at the left can be seen the ,control ,switchboards1 and overhead1 the great #cj ,k4,w4 ,arc ,transmitter with ,accessories ,the ,transformer and ,tuner of the ,world's ,largest ,radio ,station4 ,owned by the ,radio ,corporation of ,america at ,rocky ,point near ,port ,jefferson1 ,l4 ,i4 ,broadcasting ,government ,reports by ,wireless from ,washington4 ,this shows ,mr4 ,gale at work with his set in the ,post ,office ,department ,wireless ,receptor1 the size of a ,safety ,match ,box4 ,a ,youthful ,genius in the person of ,kenneth ,r4 ,hinman1 who is only twelve years old1 has made a ,wireless ,receiving ,set that fits neatly into a ,safety ,match ,box4 ,with this ,instrument and a ,pair of ,ordinary ,receivers1 he is able to catch not only ,code ,messages but the regular ,broadcasting ,programs from ,stations ,twenty and ,thirty ,miles ,distant ,wireless ,set made into a ,ring1 designed by ,alfred ,g4 ,rinehart1 of ,elizabeth1 ,new ,jersey4 ,this little ,receptor is a ,practical ,set2 it will receive ,messages1 ,concerts1 etc41 measures #a by #e_/h by #g_/h4 ,an ordinary ,umbrella is used as an ,aerial ,,chapter ,i ,,how ,,to ,,begin ,,wireless ,in writing this book it is taken for granted that you are3 first1 one of the several hundred thousand persons in the ,united ,states who are interested in wireless telegraphy and telephony2 second1 that you would like to install an apparatus in your home1 and third1 that it is all new to you4 ,now if you live in a city or town large enough to support an electrical supply store1 there you will find the necessary apparatus on sale1 and someone who can tell you what you want to know about it and how it works4 ,if you live away from the marts and hives of industry you can send to various makers of wireless apparatus ,footnote3 ,a list of makers of wireless apparatus will be found in the ,appendix4 for their catalogues and price-lists and these will give you much useful information4 ,but in either case it is the better plan for you to know before you start in to buy an outfit exactly what apparatus you need to produce the result you have in mind1 and this you can gain in easy steps by reading this book4 ,kinds of ,wireless ,systems4--,there are two distinct kinds of wireless systems and these are3 the wireless telegraph system1 and the wireless telephone system4 ,the difference between the wireless telegraph and the wireless telephone is that the former transmits messages by means of a telegraph key1 and the latter transmits conversation and music by means of a microphone transmitter4 ,in other words1 the same difference exists between them in this respect as between the ,morse telegraph and the ,bell telephone4 ,parts of a ,wireless ,system4--,every complete wireless station1 whether telegraph or telephone1 consists of three chief separate and distinct parts and these are3 7a7 the aerial wire system1 or antenna as it is often called1 7b7 the transmitter1 or sender1 and 7c7 the receiver1 or1 more properly1 the receptor4 ,the aerial wire is precisely the same for either wireless telegraphy or wireless telephony4 ,the transmitter of a wireless telegraph set generally uses a spark gap for setting up the electric oscillations1 while usually for wireless telephony a vacuum tube is employed for this purpose4 ,the receptor for wireless telegraphy and telephony is the same and may include either a crystal detector or a vacuum tube detector1 as will be explained presently4 ,the ,easiest ,way to ,start4--,first of all you must obtain a government license to operate a sending set1 but you do not need a license to put up and use a receiving set1 though you are required by law to keep secret any messages which you may overhear4 ,since no license is needed for a receiving set the easiest way to break into the wireless game is to put up an aerial and hook up a receiving set to it2 you can then listen-in and hear what is going on in the all-pervading ether around you1 and you will soon find enough to make things highly entertaining4 ,nearly all the big wireless companies have great stations fitted with powerful telephone transmitters and at given hours of the day and night they send out songs by popular singers1 dance music by jazz orchestras1 fashion talks by and for the ladies1 agricultural reports1 government weather forecasts and other interesting features4 ,then by simply shifting the slide on your tuning coil you can often tune-in someone who is sending ,morse1 that is1 messages in the dot and dash code1 or1 perhaps a friend who has a wireless telephone transmitter and is talking4 ,of course1 if you want to talk back you must have a wireless transmitter1 either telegraphic or telephonic1 and this is a much more expensive part of the apparatus than the receptor1 both in its initial cost and in its operation4 ,a wireless telegraph transmitter is less costly than a wireless telephone transmitter and it is a very good scheme for you to learn to send and receive telegraphic messages4 ,at the present time1 however1 there are fifteen amateur receiving stations in the ,united ,states to every sending station1 so you can see that the majority of wireless folks care more for listening in to the broadcasting of news and music than to sending out messages on their own account4 ,the easiest way to begin wireless1 then1 is to put up an aerial and hook up a receiving set to it4 ,about ,aerial ,wire ,systems4--,to the beginner who wants to install a wireless station the aerial wire system usually looms up as the biggest obstacle of all1 and especially is this true if his house is without a flag pole1 or other elevation from which the aerial wire can be conveniently suspended4 ,if you live in the congested part of a big city where there are no yards and1 particularly1 if you live in a flat building or an apartment house1 you will have to string your aerial wire on the roof1 and to do this you should get the owner's1 or agent's1 permission4 ,this is usually an easy thing to do where you only intend to receive messages1 for one or two thin wires supported at either end of the building are all that are needed4 ,if for any reason you cannot put your aerial on the roof then run a wire along the building outside of your apartment1 and1 finally1 if this is not feasible1 connect your receiver to a wire strung up in your room1 or even to an iron or a brass bed1 and you can still get the near-by stations4 ,an important part of the aerial wire system is the ground1 that is1 your receiving set must not only be connected with the aerial wire1 but with a wire that leads to and makes good contact with the moist earth of the ground4 ,where a house or a building is piped for gas1 water or steam1 it is easy to make a ground connection1 for all you have to do is to fasten the wire to one of the pipes with a clamp4 ,footnote3 ,pipes are often insulated from the ground1 which makes them useless for this purpose4 ,where the house is isolated then a lot of wires or a sheet of copper or of zinc must be buried in the ground at a sufficient depth to insure their being kept moist4 ,about the ,receiving ,apparatus4--,you can either buy the parts of the receiving apparatus separate and hook them up yourself1 or you can buy the apparatus already assembled in a set which is1 in the beginning1 perhaps1 the better way4 ,the simplest receiving set consists of 7#a7 a detector1 7#b7 a tuning coil1 and 7#c7 a telephone receiver and these three pieces of apparatus are1 of course1 connected together and are also connected to the aerial and ground as the diagram in ,fig4 #a clearly shows4 ,there are two chief kinds of detectors used at the present time and these are3 7a7 the crystal detector1 and 7b7 the vacuum tube detector4 ,the crystal detector is the cheapest and simplest1 but it is not as sensitive as the vacuum tube detector and it requires frequent adjustment4 ,a crystal detector can be used with or without a battery while the vacuum tube detector requires two small batteries4 ,illustration3 ,fig4 #a4--,simple ,receiving ,set4 ,a tuning coil of the simplest kind consists of a single layer of copper wire wound on a cylinder with an adjustable1 or sliding1 contact1 but for sharp tuning you need a loose coupled tuning coil4 ,where a single coil tuner is used a fixed condenser should be connected around the telephone receivers4 ,where a loose coupled tuner is employed you should have a variable condenser connected across the closed oscillation circuit and a fixed condenser across the telephone receivers4 ,when listening-in to distant stations the energy of the received wireless waves is often so very feeble that in order to hear distinctly an amplifier must be used4 ,to amplify the incoming sounds a vacuum tube made like a detector is used and sometimes as many as half-a-dozen of these tubes are connected in the receiving circuit1 or in cascade1 as it is called1 when the sounds are amplified1 that is magnified1 many hundreds of times4 ,the telephone receiver of a receiving set is equally as important as the detector4 ,a single receiver can be used but a pair of receivers connected with a head-band gives far better results4 ,then again the higher the resistance of the receivers the more sensitive they often are and those wound to as high a resistance as #c1bjj ohms are made for use with the best sets4 ,to make the incoming signals1 conversation or music1 audible to a room full of people instead of to just yourself you must use what is called a loud speaker4 ,in its simplest form this consists of a metal cone like a megaphone to which is fitted a telephone receiver4 ,about ,transmitting ,stations--,getting ,your ,license4--,if you are going to install a wireless sending apparatus1 either telegraphic or telephonic1 you will have to secure a government license for which no fee or charge of any kind is made4 ,there are three classes of licenses issued to amateurs who want to operate transmitting stations and these are3 7#a7 the restricted amateur license1 7#b7 the general amateur license1 and 7#c7 the special amateur license4 ,if you are going to set up a transmitter within five nautical miles of any naval wireless station then you will have to get a restricted amateur license which limits the current you use to half a kilowatt ,footnote3 ,a ,kilowatt is #a1jjj watts4 ,there are #gdf watts in a horsepower4 and the wave length you send out to #bjj meters4 ,should you live outside of the five-mile range of a navy station then you can get a general amateur license and this permits you to use a current of #a kilowatt1 but you are likewise limited to a wave length of #bjj meters4 ,but if you can show that you are doing some special kind of wireless work and not using your sending station for the mere pleasure you are getting out of it you may be able to get a special amateur license which gives you the right to send out wave lengths up to #cge meters4 ,when you are ready to apply for your license write to the ,radio ,inspector of whichever one of the following districts you live in3 ,first ,district44444444444444,boston1 ,mass4 ,second 44444444444444,new ,york ,city ,third 44444444444444,baltimore1 ,md4 ,fourth 44444444444444,norfolk1 ,va4 ,fifth 44444444444444,new ,orleans1 ,la4 ,sixth 4444444444444 ,san ,francisco1 ,cal4 ,seventh 4444444444444 ,seattle1 ,wash4 ,eighth 4444444444444 ,detroit1 ,mich4 ,ninth 44444444444444,chicago1 ,ill4 ,kinds of ,transmitters4--,there are two general types of transmitters used for sending out wireless messages and these are3 7#a7 wireless telegraph transmitters1 and 7#b7 wireless telephone transmitters4 ,telegraph transmitters may use either3 7a7 a jump-spark1 7b7 an electric arc1 or 7c7 a vacuum tube apparatus for sending out dot and dash messages1 while telephone transmitters may use either1 7a7 an electric arc1 or 7b7 a vacuum tube for sending out vocal and musical sounds4 ,amateurs generally use a jump-spark for sending wireless telegraph messages and the vacuum tube for sending wireless telephone messages4 ,the ,spark ,gap ,wireless ,telegraph ,transmitter4--,the simplest kind of a wireless telegraph transmitter consists of3 7#a7 a source of direct or alternating current1 7#b7 a telegraph key1 7#c7 a spark-coil or a transformer1 7#d7 a spark gap1 7#e7 an adjustable condenser and 7#f7 an oscillation transformer4 ,where dry cells or a storage battery must be used to supply the current for energizing the transmitter a spark-coil can be employed and these may be had in various sizes from a little fellow which gives #a_/d-;inch spark up to a larger one which gives a #f-;inch spark4 ,where more energy is needed it is better practice to use a transformer and this can be worked on an alternating current of #aaj volts1 or if only a #aaj volt direct current is available then an electrolytic interrupter must be used to make and break the current4 ,a simple transmitting set with an induction coil is shown in ,fig4 #b4 ,illustration3 ,fig #b4--,simple ,transmitting ,set4 ,a wireless key is made like an ordinary telegraph key except that where large currents are to be used it is somewhat heavier and is provided with large silver contact points4 ,spark gaps for amateur work are usually of3 7#a7 the plain or stationary type1 7#b7 the rotating type1 and 7#c7 the quenched gap type4 ,the plain spark-gap is more suitable for small spark-coil sets1 and it is not so apt to break down the transformer and condenser of the larger sets as the rotary gap4 ,the rotary gap on the other hand tends to prevent arcing and so the break is quicker and there is less dragging of the spark4 ,the quenched gap is more efficient than either the plain or rotary gap and moreover it is noiseless4 ,condensers for spark telegraph transmitters can be ordinary ,leyden jars or glass plates coated with tin or copper foil and set into a frame1 or they can be built up of mica and sheet metal embedded in an insulating composition4 ,the glass plate condensers are the cheapest and will serve your purpose well1 especially if they are immersed in oil4 ,tuning coils1 sometimes called transmitting inductances and oscillation transformers1 are of various types4 ,the simplest kind is a transmitting inductance which consists of #be or #cj turns of copper wire wound on an insulating tube or frame4 ,an oscillation transformer is a loose coupled tuning coil and it consists of a primary coil formed of a number of turns of copper wire wound on a fixed insulating support1 and a secondary coil of about twice the number of turns of copper wire which is likewise fixed in an insulating support1 but the coils are relatively movable4 ,an oscillation transformer 7instead of a tuning coil71 is required by government regulations unless inductively coupled4 ,the ,vacuum ,tube ,telegraph ,transmitter4--,this consists of3 7#a7 a source of direct or alternating current1 7#b7 a telegraph key1 7#c7 a vacuum tube oscillator1 7#d7 a tuning coil1 and 7#e7 a condenser4 ,this kind of a transmitter sets up sustained oscillations instead of periodic oscillations which are produced by a spark gap set4 ,the advantages of this kind of a system will be found explained in ,chapter ,,xvi4 ,the ,wireless ,telephone ,transmitter4--,because a jump-spark sets up periodic oscillations1 that is1 the oscillations are discontinuous1 it cannot be used for wireless telephony4 ,an electric arc or a vacuum tube sets up sustained oscillations1 that is1 oscillations which are continuous4 ,as it is far easier to keep the oscillations going with a vacuum tube than it is with an arc the former means has all but supplanted the latter for wireless telephone transmitters4 ,the apparatus required and the connections used for wireless telephone sets will be described in later chapters4 ,useful ,information4--,it would be wise for the reader to turn to the ,appendix1 beginning with page #cja of this book1 and familiarize himself with the information there set down in tabular and graphic form4 ,for example1 the first table gives abbreviations of electrical terms which are in general use in all works dealing with the subject4 ,you will also find there brief definitions of electric and magnetic units1 which it would be well to commit to memory2 or1 at least1 to make so thoroughly your own that when any of these terms is mentioned1 you will know instantly what is being talked about4 ,,chapter ,,ii ,,putting ,,up ,,your ,,aerial ,as inferred in the first chapter1 an aerial for receiving does not have to be nearly as well made or put up as one for sending4 ,but this does not mean that you can slipshod the construction and installation of it1 for however simple it is1 the job must be done right and in this case it is as easy to do it right as wrong4 ,to send wireless telegraph and telephone messages to the greatest distances and to receive them as distinctly as possible from the greatest distances you must use for your aerial 7#a7 copper or aluminum wire1 7#b7 two or more wires1 7#c7 have them the proper length1 7#d7 have them as high in the air as you can1 7#e7 have them well apart from each other1 and 7#f7 have them well insulated from their supports4 ,if you live in a flat building or an apartment house you can string your aerial wires from one edge of the roof to the other and support them by wooden stays as high above it as may be convenient4 ,should you live in a detached house in the city you can usually get your next-door neighbor to let you fasten one end of the aerial to his house and this will give you a good stretch and a fairly high aerial4 ,in the country you can stretch your wires between the house and barn or the windmill4 ,from this you will see that no matter where you live you can nearly always find ways and means of putting up an aerial that will serve your needs without going to the expense of erecting a mast4 ,kinds of ,aerial ,wire ,systems4--,an amateur wireless aerial can be anywhere from #be feet to #ajj feet long and if you can get a stretch of the latter length and a height of from #cj to #ge feet you will have one with which you can receive a thousand miles or more and send out as much energy as the government will allow you to send4 ,the kind of an aerial that gives the best results is one whose wire1 or wires1 are horizontal1 that is1 parallel with the earth under it as shown at ,a in ,fig4 #c4 ,if only one end can be fixed to some elevated support then you can secure the other end to a post in the ground1 but the slope of the aerial should not be more than #cj or #ce degrees from the horizontal at most as shown at ,b4 ,illustration3 7,a7 ,fig4 #c4--;,flat top1 or ,horizontal ,aerial4 ,illustration3 7,b7 ,fig4 #c4--;,inclined ,aerial4 ,the leading-in wire1 that is1 the wire that leads from and joins the aerial wire with your sending and receiving set1 can be connected to the aerial anywhere it is most convenient to do so1 but the best results are had when it is connected to one end as shown at ,a in ,fig4 #d1 in which case it is called an inverted ,l aerial1 or when it is connected to it at the middle as shown at ,b1 when it is called a ,t aerial4 ,the leading-in wire must be carefully insulated from the outside of the building and also where it passes through it to the inside4 ,this is done by means of an insulating tube known as a leading-in insulator1 or bulkhead insulator as it is sometimes called4 ,illustration3 7,a7 ,fig4 #d4--;,inverted ,l ,aerial4 ,illustration3 7,b7 ,fig4 #d4--,t ,aerial4 ,as a protection against lightning burning out your instruments you can use either3 7#a7 an air-gap lightning arrester1 7#b7 a vacuum tube protector1 or 7#c7 a lightning switch1 which is better4 ,whichever of these devices is used it is connected in between the aerial and an outside ground wire so that a direct circuit to the earth will be provided at all times except when you are sending or receiving4 ,so your aerial instead of being a menace really acts during an electrical storm like a lightning rod and it is therefore a real protection4 ,the air-gap and vacuum tube lightning arresters are little devices that can be used only where you are going to receive1 while the lightning switch must be used where you are going to send2 indeed1 in some localities the ,fire ,underwriters require a large lightning switch to be used for receiving sets as well as sending sets4 ,how to ,put ,up a ,cheap ,receiving ,aerial4--,the kind of an aerial wire system you put up will depend1 chiefly1 on two things1 and these are3 7#a7 your pocketbook1 and 7#b7 the place where you live4 ,a ,single ,wire ,aerial4--,this is the simplest and cheapest kind of a receiving aerial that can be put up4 ,the first thing to do is to find out the length of wire you need by measuring the span between the two points of support2 then add a sufficient length for the leading-in wire and enough more to connect your receiving set with the radiator or water pipe4 ,you can use any size of copper or aluminum wire that is not smaller than ,no4 #af ,brown and ,sharpe gauge4 ,when you buy the wire get also the following material3 7#a7 two porcelain insulators as shown at ,a in ,fig4 #e2 7#b7 three or four porcelain knob insulators1 see ,b2 7#c7 either 7a7 an air gap lightning arrester1 see ,c1 or 7b7 a lightning switch see ,d2 7#d7 a leading-in porcelain tube insulator1 see ,e1 and 7#e7 a ground clamp1 see ,f4 ,illustration3 ,fig4 #e4--,material for a ,simple ,aerial ,wire ,system4 ,to make the aerial slip each end of the wire through a hole in each insulator and twist it fast2 next cut off and slip two more pieces of wire through the other holes in the insulators and twist them fast and then secure these to the supports at the ends of the building4 ,take the piece you are going to use for the leading-in wire1 twist it around the aerial wire and solder it there when it will look like ,a in ,fig4 #f4 ,now if you intend to use the air gap lightning arrester fasten it to the wall of the building outside of your window1 and bring the leading-in wire from the aerial to the top binding post of your arrester and keep it clear of everything as shown at ,b4 ,if your aerial is on the roof and you have to bring the leading-in wire over the cornice or around a corner fix a porcelain knob insulator to the one or the other and fasten the wire to it4 ,illustration3 7,a7 ,fig4 #f4--,single ,wire ,aerial for ,receiving4 ,illustration3 7,b7 ,fig4 #f4--,receiving ,aerial with ,air ,gap ,lightning ,arrester4 ,illustration3 7,c7 ,fig4 #f4--;,aerial with ,lightning ,switch4 ,next bore a hole through the frame of the window at a point nearest your receiving set and push a porcelain tube #e_/h inch in diameter and #e or #f inches long1 through it4 ,connect a length of wire to the top post of the arrester or just above it to the wire1 run this through the leading-in insulator and connect it to the slider of your tuning coil4 ,screw the end of a piece of heavy copper wire to the lower post of the arrester and run it to the ground1 on porcelain knobs if necessary1 and solder it to an iron rod or pipe which you have driven into the earth4 ,finally connect the fixed terminal of your tuning coil with the water pipe or radiator inside of the house by means of the ground clamp as shown in the diagrammatic sketch at ,b in ,fig4 #f and you are ready to tune in4 ,if you want to use a lightning switch instead of the air-gap arrester then fasten it to the outside wall instead of the latter and screw the free end of the leading-in wire from the aerial to the middle post of it as shown at ,c in ,fig4 #f4 ,run a wire from the top post through the leading-in insulator and connect it with the slider of your tuning coil4 ,next screw one end of a length of heavy copper wire to the lower post of the aerial switch and run it to an iron pipe in the ground as described above in connection with the spark-gap lightning arrester2 then connect the fixed terminal of your tuning coil with the radiator or water pipe and your aerial wire system will be complete as shown at ,c in ,fig4 #f4 ,a ,two-wire ,aerial4--,an aerial with two wires will give better results than a single wire and three wires are better than two1 but you must keep them well apart4 ,to put up a two-wire aerial get 7#a7 enough ,no4 #af1 or preferably ,no4 #ad1 solid or stranded copper or aluminum wire1 7#b7 four porcelain insulators1 see ,b in ,fig4 #e1 and 7#c7 two sticks about #a inch thick1 #c inches wide and #c or #d feet long1 for the spreaders1 and bore #a_/h-;inch hole through each end of each one4 ,now twist the ends of the wires to the insulators and then cut off four pieces of wire about #f feet long and run them through the holes in the wood spreaders4 ,finally twist the ends of each pair of short wires to the free ends of the insulators and then twist the free ends of the wires together4 ,for the leading-in wire that goes to the lightning switch take two lengths of wire and twist one end of each one around the aerial wires and solder them there4 ,twist the short wire around the long wire and solder this joint also when the aerial will look like ,fig4 #g4 ,bring the free end of the leading-in wire down to the middle post of the lightning switch and fasten it there and connect up the receiver to it and the ground as described under the caption of ,a ,single ,wire ,aerial4 ,illustration3 ,fig4 #g4--,two ,wire ,aerial4 ,connecting in the ,ground4--,if there is a gas or water system or a steam-heating plant in your house you can make your ground connection by clamping a ground clamp to the nearest pipe as has been previously described4 ,connect a length of bare or insulated copper wire with it and bring this up to the table on which you have your receiving set4 ,if there are no grounded pipes available then you will have to make a good ground which we shall describe presently and lead the ground wire from your receiving set out of the window and down to it4 ,how to ,put ,up a ,good ,aerial4--,while you can use the cheap aerial already described for a small spark-coil sending set you should have a better insulated one for a #a_/b or a #a kilowatt transformer set4 ,the cost for the materials for a good aerial is small and when properly made and well insulated it will give results that are all out of proportion to the cost of it4 ,an ,inexpensive ,good ,aerial4--,a far better aerial1 because it is more highly insulated1 can be made by using midget insulators instead of the porcelain insulators described under the caption of ,a ,single ,wire ,aerial and using a small electrose leading-in insulator instead of the porcelain bushing4 ,this makes a good sending aerial for small sets as well as a good receiving aerial4 ,the ,best ,aerial that ,can ,be ,made4--,to make this aerial get the following material together3 7#a7 enough stranded or braided wire for three or four lengths of parallel wires1 according to the number you want to use 7#b7 six or eight electrose ball insulators1 see ,b1 ,fig4 #h2 7#c7 two #e-;inch or #aj-;inch electrose strain insulators1 see ,c2 7#d7 six or eight ,s-hooks1 see ,d2 one large withe with one eye for middle of end spreader1 see ,e2 7#f7 two smaller withes with one eye each for end spreader1 see ,e2 7#g7 two still smaller withes1 with two eyes each for the ends of the end spreaders1 see ,e 7#h7 two thimbles1 see ,f1 for #a_/d-;inch wire cable2 7#i7 six or eight hard rubber tubes or bushings as shown at ,g2 and 7#aj7 two end spreaders1 see ,h2 one middle spreader1 see ,i2 and one leading-in spreader1 see ,j4 ,illustration3 7,a7 ,fig4 #h--,part of a ,good ,aerial4 ,illustration3 7,b7 ,fig4 #h4--,the ,spreaders4 ,for this aerial any one of a number of kinds of wire can be used and among these are 7a7 stranded copper wire2 7b7 braided copper wire2 7c7 stranded silicon bronze wire1 and 7d7 stranded phosphor bronze wire4 ,stranded and braided copper wire is very flexible as it is formed of seven strands of fine wire twisted or braided together and it is very good for short and light aerials4 ,silicon bronze wire is stronger than copper wire and should be used where aerials are more than #ajj feet long1 while phosphor bronze wire is the strongest aerial wire made and is used for high grade aerials by the commercial companies and the ,government for their high-power stations4 ,the spreaders should be made of spruce1 and should be #d feet #aj inches long for a three-wire aerial and #g feet #a inch long for a four-wire aerial as the distance between the wires should be about #bg inches4 ,the end spreaders can be turned cylindrically but it makes a better looking job if they taper from the middle to the ends4 ,they should be #b-a_/d inches in diameter at the middle and #a-c_/d inches at the ends4 ,the middle spreader can be cylindrical and #b inches in diameter4 ,it must have holes bored through it at equidistant points for the hard rubber tubes2 each of these should be #e_/h inch in diameter and have a hole #e_/cb inch in diameter through it for the aerial wire4 ,the leading-in spreader is also made of spruce and is #a-a_/b inches square and #bf inches long4 ,bore three or four #e_/h-;inch holes at equidistant points through this spreader and insert hard rubber tubes in them as with the middle spreader4 ,assembling the ,aerial4--,begin by measuring off the length of each wire to be used and see to it that all of them are of exactly the same length4 ,now push the hard rubber insulators through the holes in the middle spreader and thread the wires through the holes in the insulators as shown at ,a in ,fig #i4 ,next twist the ends of each wire to the rings of the ball insulators and then put the large withes on the middle of each of the end spreaders2 fix the other withes on the spreaders so that they will be #bg inches apart and fasten the ball insulators to the eyes in the withes with the ,s-hooks4 ,now slip a thimble through the eye of one of the long strain insulators1 thread a length of stranded steel wire #a_/d inch in diameter through it and fasten the ends of it to the eyes in the withes on the ends of the spreaders4 ,illustration3 7,a7 ,fig4 #i4--,middle ,spreader4 ,illustration3 7,b7 ,fig4 #i4--,one ,end of ,aerial ,complete4 ,illustration3 7,c7 ,fig4 #i4--,leading in ,spreader4 ,finally fasten a #dj-;inch length of steel stranded wire to each of the eyes of the withes on the middle of each of the spreaders1 loop the other end over the thimble and then wrap the end around the wires that are fixed to the ends of the spreaders4 ,one end of the aerial is shown complete at ,b in ,fig4 #i1 and from this you can see exactly how it is assembled4 ,now cut off three or four pieces of wire #ae or #bj feet long and twist and solder each one to one of the aerial wires2 then slip them through the hard rubber tubes in the leading-in spreader1 bring their free ends together as at ,c and twist and solder them to a length of wire long enough to reach to your lightning switch or instruments4 ,making a ,good ,ground4--,where you have to make a ground you can do so either by 7#a7 burying sheets of zinc or copper in the moist earth2 7#b7 burying a number of wires in the moist earth1 or 7#c7 using a counterpoise4 ,to make a ground of the first kind take half a dozen large sheets of copper or zinc1 cut them into strips a foot wide1 solder them all together with other strips and bury them deeply in the ground4 ,it is easier to make a wire ground1 say of as many or more wires as you have in your aerial and connect them together with cross wires4 ,to put such a ground in the earth you will have to use a plow to make the furrows deep enough to insure them always being moist4 ,in the counterpoise ground you make up a system of wires exactly like your aerial1 that is1 you insulate them just as carefully2 then you support them so that they will be as close to the ground as possible and yet not touch it or anything else4 ,this and the other two grounds just described should be placed directly under the aerial wire if the best results are to be had4 ,in using a counterpoise you must bring the wire from it up to and through another leading-in insulator to your instruments4 ,,chapter ,,iii ,,simple ,,telegraph ,,and ,,telephone ,,receiving ,,sets ,with a crystal detector receiving set you can receive either telegraphic dots and dashes or telephonic speech and music4 ,you can buy a receiving set already assembled or you can buy the different parts and assemble them yourself4 ,an assembled set is less bother in the beginning but if you like to experiment you can hook up1 that is1 connect the separate parts together yourself and it is perhaps a little cheaper to do it this way4 ,then again1 by so doing you get a lot of valuable experience in wireless work and an understanding of the workings of wireless that you cannot get in any other way4 ,assembled ,wireless ,receiving ,sets4--,the cheapest assembled receiving set ,footnote3 ,the ,marvel1 made by the ,radio ,mfg4 ,co41 ,new ,york ,city4 advertised is one in which the detector and tuning coil is mounted in a box4 ,it costs #ae4jj1 and can be bought of dealers in electric supplies generally4 ,this price also includes a crystal detector1 an adjustable tuning coil1 a single telephone receiver with head-band and the wire1 porcelain insulators1 lightning switch and ground clamp for the aerial wire system4 ,it will receive wireless telegraph and telephone messages over a range of from #aj to #be miles4 ,another cheap unit receptor1 that is1 a complete wireless receiving set already mounted which can be used with a single aerial is sold for #be4jj4 ,footnote3 ,the ,aeriola ,jr41 made by the ,westinghouse ,company1 ,pittsburgh1 ,pa4 ,this set includes a crystal detector1 a variable tuning coil1 a fixed condenser and a pair of head telephone receivers4 ,it can also be used to receive either telegraph or telephone messages from distances up to #be miles4 ,the aerial equipment is not included in this price1 but it can be bought for about #b4ej extra4 ,assembling ,your ,own ,receiving ,set4--,in this chapter we shall go only into the apparatus used for two simple receiving sets1 both of which have a crystal detector4 ,the first set includes a double-slide tuning coil and the second set employs a loose-coupled tuning coil1 or loose coupler1 as it is called for short4 ,for either set you can use a pair of #b1jjj- or #c1jjj-ohm head phones4 ,illustration3 original ,underwood and ,underwood4 ,general ,pershing ,listening ,in4 ,the ,crystal ,detector4--,a crystal detector consists of3 7#a7 the frame1 7#b7 the crystal1 and 7#c7 the wire point4 ,there are any number of different designs for frames1 the idea being to provide a device that will 7a7 hold the sensitive crystal firmly in place1 and yet permit of its removal1 7b7 to permit the wire point1 or electrode1 to be moved in any direction so that the free point of it can make contact with the most sensitive spot on the crystal and 7c7 to vary the pressure of the wire on the crystal4 ,a simple detector frame is shown in the cross-section at ,a in ,fig4 #aj2 the crystal1 which may be galena1 silicon or iron pyrites1 is held securely in a holder while the phosphor-bronze wire point which makes contact with it1 is fixed to one end of a threaded rod on the other end of which is a knob4 ,this rod screws into and through a sleeve fixed to a ball that sets between two brass standards and this permits an up and down or a side to side adjustment of the metal point while the pressure of it on the crystal is regulated by the screw4 ,illustration3 7,a7 ,fig4 #aj4--;,cross ,section of ,crystal ,detector4 ,illustration3 7,b7 ,fig4 #aj4--,the ,crystal ,detector ,complete4 ,a crystal of this kind is often enclosed in a glass cylinder and this makes it retain its sensitiveness for a much longer time than if it were exposed to dust and moisture4 ,an upright type of this detector can be bought for #b4be1 while a horizontal type1 as shown at ,b1 can be bought for #b4ge4 ,galena is the crystal that is generally used1 for1 while it is not quite as sensitive as silicon and iron pyrites1 it is easier to obtain a sensitive piece4 ,the ,tuning ,coil4--,it is with the tuning coil that you tune in and tune out different stations and this you do by sliding the contacts to and fro over the turns of wire2 in this way you vary the inductance and capacitance1 that is1 the constants of the receiving circuits and so make them receive electric waves1 that is1 wireless waves1 of different lengths4 ,the ,double ,slide ,tuning ,coil4--,with this tuning coil you can receive waves from any station up to #a1jjj meters in length4 ,one of the ends of the coil of wire connects with the binding post marked a in ,fig4 #aa1 and the other end connects with the other binding post marked b1 while one of the sliding contacts is connected to the binding post c1 and the other sliding contact is connected with the binding post d4 ,illustration3 7,a7 ,fig4 #aa4--,schematic ,diagram of ,double ,slide ,tuning ,coil4 ,illustration3 7,b7 ,fig4 #aa4--;,double ,slide ,tuning ,coil ,complete4 ,when connecting in the tuning coil1 only the post a or the post b is used as may be most convenient1 but the other end of the wire which is connected to a post is left free2 just bear this point in mind when you come to connect the tuning coil up with the other parts of your receiving set4 ,the tuning coil is shown complete at ,b and it costs #c4jj or #d4jj4 ,a triple slide tuning coil constructed like the double slide tuner just described1 only with more turns of wire on it1 makes it possible to receive wave lengths up to #a1ejj meters4 ,it costs about #f4jj4 ,the ,loose ,coupled ,tuning ,coil4--,with a loose coupler1 as this kind of a tuning coil is called for short1 very selective tuning is possible1 which means that you can tune in a station very sharply1 and it will receive any wave lengths according to size of coils4 ,the primary coil is wound on a fixed cylinder and its inductance is varied by means of a sliding contact like the double slide tuning coil described above4 ,the secondary coil is wound on a cylinder that slides in and out of the primary coil4 ,the inductance of this coil is varied by means of a switch that makes contact with the fixed points1 each of which is connected with every twentieth turn of wire as shown in the diagram ,a in ,fig4 #ab4 ,the loose coupler1 which is shown complete at ,b1 costs in the neighborhood of #h4jj or #aj4jj4 ,illustration3 7,a7 ,fig4 #ab4--,schematic ,diagram of ,loose ,coupler4 ,illustration3 7,b7 ,fig4 #ab4--,loose ,coupler ,complete4 ,fixed and ,variable ,condensers4--,you do not require a condenser for a simple receiving set1 but if you will connect a fixed condenser across your headphones you will get better results1 while a variable condenser connected in the closed circuit of a direct coupled receiving set1 that is1 one where a double slide tuning coil is used1 makes it easy to tune very much more sharply2 a variable condenser is absolutely necessary where the circuits are inductively coupled1 that is1 where a loose coupled tuner is used4 ,a fixed condenser consists of a number of sheets of paper with leaves of tin-foil in between them and so built up that one end of every other leaf of tin-foil projects from the opposite end of the paper as shown at ,a in ,fig4 #ac4 ,the paper and tin-foil are then pressed together and impregnated with an insulating compound4 ,a fixed condenser of the exact capacitance required for connecting across the head phones is mounted in a base fitted with binding posts1 as shown at ,b1 and costs #ge cents4 7,paper ones #be cents47 ,illustration3 7,a7 ,fig4 #ac4--;,how a ,fixed ,receiving ,condenser is ,built up4 ,illustration3 7,b7 ,fig4 #ac4--,the ,fixed ,condenser ,complete4 ,illustration3 7,c7 and 7,d7 ,fig4 #ac4--,the ,variable ,rotary ,condenser4 ,a variable condenser1 see ,c1 of the rotating type is formed of a set of fixed semi-circular metal plates which are slightly separated from each other and between these a similar set of movable semi-circular metal plates is made to interleave2 the latter are secured to a shaft on the top end of which is a knob and by turning it the capacitance of the condenser1 and1 hence1 of the circuit in which it is connected1 is varied4 ,this condenser1 which is shown at ,d1 is made in two sizes1 the smaller one being large enough for all ordinary wave lengths while the larger one is for proportionately longer wave lengths4 ,these condensers cost #d4jj and #e4jj respectively4 ,about ,telephone ,receivers4--,there are a number of makes of head telephone receivers on the market that are designed especially for wireless work4 ,these phones are wound to resistances of from #ge ohms to #h1jjj ohms1 and cost from #a4be for a receiver without a cord or headband to #ae4jj for a pair of phones with a cord and head band4 ,you can get a receiver wound to any resistance in between the above values but for either of the simple receiving sets such as described in this chapter you ought to have a pair wound to at least #b1jjj ohms and these will cost you about #e4jj4 ,a pair of head phones of this type is shown in ,fig4 #ad4 ,illustration3 ,fig4 #ad4--,pair of ,wireless ,head ,phones4 ,connecting ,up the ,parts--,receiving ,set ,no4 #a4--;,for this set get 7#a7 a crystal detector1 7#b7 a two-slide tuning coil1 7#c7 a fixed condenser1 and 7#d7 a pair of #b1jjj ohm head phones4 ,mount the detector on the right-hand side of a board and the tuning coil on the left-hand side4 ,screw in two binding posts for the cord ends of the telephone receivers at a and b as shown at ,a in ,fig4 #ae4 ,this done connect one of the end binding posts of the tuning coil with the ground wire and a post of one of the contact slides with the lightning arrester or switch which leads to the aerial wire4 ,illustration3 ,fig4 #ae4--,top ,view of ,apparatus ,layout for ,receiving ,set ,no4 #a4 ,illustration3 7,b7 ,fig4 #ae4--,wiring ,diagram for ,receiving ,set ,no4 #a4 ,now connect the post of the other contact slide to one of the posts of the detector and the other post of the latter with the binding post a1 then connect the binding post b to the ground wire and solder the joint4 ,next connect the ends of the telephone receiver cord to the posts a and b and connect a fixed condenser also with these posts1 all of which are shown in the wiring diagram at ,b1 and you are ready to adjust the set for receiving4 ,receiving ,set ,no4 #b4--,use the same kind of a detector and pair of head phones as for ,set ,no4 #a1 but get 7#a7 a loose coupled tuning coil1 and 7#b7 a variable condenser4 ,mount the loose coupler at the back of a board on the left-hand side and the variable condenser on the right-hand side4 ,then mount the detector in front of the variable condenser and screw two binding posts1 a and b1 in front of the tuning coil as shown at ,a in ,fig4 #af4 ,illustration3 ,fig4 #af4--,top view of ,apparatus ,layout for ,receiving ,set ,no4 #b4 ,illustration3 7,b7 ,fig4 #af4--,wiring ,diagram for ,receiving ,set ,no4 #b4 ,now connect the post of the sliding contact of the loose coupler with the wire that runs to the lightning switch and thence to the aerial2 connect the post of the primary coil1 which is the outside coil1 with the ground wire2 then connect the binding post leading to the switch of the secondary coil1 which is the inside coil1 with one of the posts of the variable condenser1 and finally1 connect the post that is joined to one end of the secondary coil with the other post of the variable condenser4 ,this done1 connect one of the posts of the condenser with one of the posts of the detector1 the other post of the detector with the binding post a1 and the post b to the other post of the variable condenser4 ,next connect a fixed condenser to the binding posts a and b and then connect the telephone receivers to these same posts1 all of which is shown in the wiring diagram at ,b4 ,you are now ready to adjust the instruments4 ,in making the connections use ,no4 #af or #ah insulated copper wire and scrape the ends clean where they go into the binding posts4 ,see1 also1 that all of the connections are tight and where you have to cross the wires keep them apart by an inch or so and always cross them at right angles4 ,adjusting the ,no4 #a ,set--,the ,detector4--,the first thing to do is to test the detector in order to find out if the point of the contact wire is on a sensitive spot of the crystal4 ,to do this you need a buzzer1 a switch and a dry cell4 ,an electric bell from which the gong has been removed will do for the buzzer1 but you can get one that is made specially for the purpose1 for #ge cents1 which gives out a clear1 high-pitched note that sounds like a high-power station4 ,connect one of the binding posts of the buzzer with one post of the switch1 the other post of the latter with the zinc post of the dry cell and the carbon post of this to the other post of the buzzer4 ,then connect the post of the buzzer that is joined to the vibrator1 to the ground wire as shown in the wiring diagram1 ,fig4 #ag4 ,now close the switch of the buzzer circuit1 put on your head phones1 and move the wire point of the detector to various spots on the crystal until you hear the sparks made by the buzzer in your phones4 ,illustration3 ,fig4 #ag4--;,adjusting the ,receiving ,set4 ,then vary the pressure of the point on the crystal until you hear the sparks as loud as possible4 ,after you have made the adjustment open the switch and disconnect the buzzer wire from the ground wire of your set4 ,this done1 be very careful not to jar the detector or you will throw it out of adjustment and then you will have to do it all over again4 ,you are now ready to tune the set with the tuning coil and listen in4 ,the ,tuning ,coil4--,to tune this set move the slide ,a of the double-slide tuner1 see ,b in ,fig4 #ae1 over to the end of the coil that is connected with the ground wire and the slide ,b near the opposite end of the coil1 that is1 the one that has the free end4 ,now move the slide ,a toward the ,b slide and when you hear the dots and dashes1 or speech or music1 that is coming in as loud as you can move the ,b slide toward the ,a slide until you hear still more loudly4 ,a very few trials on your part and you will be able to tune in or tune out any station you can hear1 if not too close or powerful4 ,illustration3 original ,underwood and ,underwood4 ,the ,world's ,largest ,radio ,receiving ,station4 ,owned by the ,radio ,corporation of ,america at ,rocky ,point near ,point ,jefferson1 ,l4,i4 ,adjusting the ,no4 #b ,set4--,first adjust the crystal detector with the buzzer set as described above with ,set ,no4 #a1 then turn the knob of your variable condenser so that the movable plates are just half-way in1 pull the secondary coil of your loose-coupled tuner half way out2 turn the switch lever on it until it makes a contact with the middle contact point and set the slider of the primary coil half way between the ends4 ,now listen in for telegraphic signals or telephonic speech or music2 when you hear one or the other slide the secondary coil in and out of the primary coil until the sounds are loudest2 now move the contact switch over the points forth and back until the sounds are still louder1 then move the slider to and fro until the sounds are yet louder and1 finally1 turn the knob of the condenser until the sounds are clear and crisp4 ,when you have done all of these things you have1 in the parlance of the wireless operator1 tuned in and you are ready to receive whatever is being sent4 ,,chapter ,,iv ,,simple ,,telegraph ,,sending ,,sets ,a wireless telegraph transmitting set can be installed for a very small amount of money provided you are content with one that has a limited range4 ,larger and better instruments can1 of course1 be had for more money1 but however much you are willing to spend still you are limited in your sending radius by the ,government's rules and regulations4 ,the best way1 and the cheapest in the end1 to install a telegraph set is to buy the separate parts and hook them up yourself4 ,the usual type of wireless telegraph transmitter employs a disruptive discharge1 or spark1 as it is called1 for setting up the oscillating currents in the aerial wire system and this is the type of apparatus described in this chapter4 ,there are two ways to set up the sparks and these are3 7#a7 with an induction coil1 or spark-coil1 as it is commonly called1 and 7#b7 with an alternating current transformer1 or power transformer1 as it is sometimes called4 ,where you have to generate the current with a battery you must use a spark coil1 but if you have a #aaj-volt direct or alternating lighting current in your home you can use a transformer which will give you more power4 ,a ,cheap ,transmitting ,set 7,no4 #a74--;,for this set you will need3 7#a7 a spark-coil1 7#b7 a battery of dry cells1 7#c7 a telegraph key1 7#d7 a spark gap1 7#e7 a high-tension condenser1 and 7#f7 an oscillation transformer4 ,there are many different makes and styles of these parts but in the last analysis all of them are built on the same underlying bases and work on the same fundamental principles4 ,the ,spark-,coil4--,spark coils for wireless work are made to give sparks from #a_/d inch in length up to #f inches in length1 but as a spark coil that gives less than a #a-;inch spark has a very limited output it is best to get a coil that gives at least a #a-;inch spark1 as this only costs about #h4jj1 and if you can get a #b- or a #d-;inch spark coil so much the better4 ,there are two general styles of spark coils used for wireless and these are shown at ,a and ,b in ,fig4 #ah4 ,illustration3 7,a7 and 7,b7 ,fig4 #ah4--,types of ,spark ,coils for ,set4 ,no4 #a4 ,illustration3 7,c7 ,fig4 #ah4--,wiring ,diagram of ,spark ,coil ,a spark coil of either style consists of 7a7 a soft iron core on which is wound 7b7 a couple of layers of heavy insulated wire and this is called the primary coil1 7c7 while over this1 but insulated from it1 is wound a large number of turns of very fine insulated copper wire called the secondary coil2 7d7 an interrupter1 or vibrator1 as it is commonly called1 and1 finally1 7e7 a condenser4 ,the core1 primary and secondary coils form a unit and these are set in a box or mounted on top of a hollow wooden base4 ,the condenser is placed in the bottom of the box1 or on the base1 while the vibrator is mounted on one end of the box or on top of the base1 and it is the only part of the coil that needs adjusting4 ,the vibrator consists of a stiff1 flat spring fixed at one end to the box or base while it carries a piece of soft iron called an armature on its free end and this sets close to one end of the soft iron core4 ,insulated from this spring is a standard that carries an adjusting screw on the small end of which is a platinum point and this makes contact with a small platinum disk fixed to the spring4 ,the condenser is formed of alternate sheets of paper and tinfoil built up in the same fashion as the receiving condenser described under the caption of ,fixed and ,variable ,condensers1 in ,chapter ,,iii4 ,the wiring diagram ,c shows how the spark coil is wired up4 ,one of the battery binding posts is connected with one end of the primary coil while the other end of the latter which is wound on the soft iron core connects with the spring of the vibrator4 ,the other battery binding post connects with the standard that supports the adjusting screw4 ,the condenser is shunted across the vibrator1 that is1 one end of the condenser is connected with the spring and the other end of the condenser is connected with the adjusting screw standard4 ,the ends of the secondary coil lead to two binding posts1 which are usually placed on top of the spark coil and it is to these that the spark gap is connected4 ,the ,battery4--,this can be formed of dry cells or you can use a storage battery to energize your coil4 ,for all coils that give less than a #a-;inch spark you should use #e dry cells2 for #a-;and #b-;inch spark coils use #f or #h dry cells1 and for #c to #d-;inch spark coils use #h to #aj dry cells4 ,the way the dry cells are connected together to form a battery will be shown presently4 ,a dry cell is shown at ,a in ,fig1 #ai4 ,illustration3 ,fig4 #ai4--,other parts for ,transmitting ,set ,no4 #a ,the ,telegraph ,key4--,you can use an ordinary ,morse telegraph key for the sending set and you can get one with a japanned iron base for #a4ej 7or better1 one made of brass and which has #a_/h-;inch silver contact points for #c4jj4 ,a key of the latter kind is shown at ,b74 ,the ,spark gap4--,it is in the spark gap that the high tension spark takes place4 ,the apparatus in which the spark takes place is also called the spark gap4 ,it consists of a pair of zinc plugs1 called electrodes1 fixed to the ends of a pair of threaded rods1 with knobs on the other ends1 and these screw into and through a pair of standards as shown at c4 ,this is called a fixed1 or stationary spark gap and costs about #a4jj4 ,the ,tuning ,coil4--,the transmitting inductance1 or sending tuning coil1 consists of #bj to #cj turns of ,no4 #h or #i hard drawn copper wire wound on a slotted insulated form and mounted on a wooden base4 ,it is provided with clips so that you can cut in and cut out as many turns of wire as you wish and so tune the sending circuits to send out whatever wave length you desire4 ,it is shown at d1 and costs about #e4jj4 ,see also ,oscillation ,transformer1 page #fc ,chapter ,,iv4 ,the ,high ,tension ,condenser4--,high tension condensers1 that is1 condensers which will stand up under high potentials1 or electric pressures1 can be bought in units or sections4 ,these condensers are made up of thin brass plates insulated with a special compound and pressed into a compact form4 ,the capacitance ,footnote3 ,this is the capacity of the condenser4 of one section is enough for a transmitting set using a spark coil that gives a #b inch spark or less and two sections connected together should be used for coils giving from #b to #d inch sparks4 ,it is shown at e4 ,connecting ,up the ,apparatus4--,your sending set should be mounted on a table1 or a bench1 where it need not be moved4 ,place the key in about the middle of the table and down in front1 and the spark coil to the left and well to the back but so that the vibrator end will be to the right1 as this will enable you to adjust it easily4 ,place the battery back of the spark coil and the tuning coil 7oscillation transformer7 to the right of the spark coil and back of the key1 all of which is shown in the layout at ,a in ,fig4 #bj4 ,illustration3 7,a7 ,fig4 #bj4--,top ,view of ,apparatus ,layout for ,sending ,set ,no4 #a4 ,illustration3 7,b7 ,fig4 #bj4--,wiring of ,diagram for ,sending ,set ,no4 #a4 ,for the low voltage circuit1 that is the battery circuit1 use ,no4 #ab or #ad insulated copper wire4 ,connect all of the dry cells together in series1 that is1 connect the zinc of one cell with the carbon of the next and so on until all of them are connected up4 ,then connect the carbon of the end cell with one of the posts of the key1 the zinc of the other end cell with one of the primary posts of the spark coil and the other primary post of the spark coil with the other post of the key1 when the primary circuit will be complete4 ,for the high tension circuits1 that is1 the oscillation circuits1 you may use either bare or insulated copper wire but you must be careful that they do not touch the table1 each other1 or any part of the apparatus1 except1 of course1 the posts they are connected with4 ,connect one of the posts of the secondary coil of the spark coil with one of the posts of the spark gap1 and the other post with one of the posts of the condenser2 then connect the other post of the condenser with the lower spring clip of the tuning coil and also connect this clip with the ground4 ,this done1 connect the middle spring clip with one of the posts of the spark gap1 and1 finally1 connect the top clip with the aerial wire and your transmitting set is ready to be tuned4 ,a wiring diagram of the connections is shown at ,b4 ,as this set is tuned in the same way as ,set ,no4 #b which follows1 you are referred to the end of this chapter4 ,a ,better ,transmitting ,set 7,no4 #b74--,the apparatus for this set includes3 7#a7 an alternating current transformer1 7#b7 a wireless telegraph key1 7#c7 a fixed1 a rotary1 or a quenched spark gap1 7#d7 a condenser1 and 7#e7 an oscillation transformer4 ,if you have a #aaj volt direct lighting current in your home instead of #aaj volt alternating current1 then you will also need 7#f7 an electrolytic interrupter1 for in this case the primary circuit of the transformer must be made and broken rapidly in order to set up alternating currents in the secondary coil4 ,the ,alternating ,current ,transformer4--,an alternating current1 or power1 transformer is made on the same principle as a spark coil1 that is1 it has a soft iron core1 a primary coil formed of a couple of layers of heavy wire1 and a secondary coil wound up of a large number of turns of very fine wire4 ,unlike the spark coil1 however1 which has an open magnetic core and whose secondary coil is wound on the primary coil1 the transformer has a closed magnetic core1 with the primary coil wound on one of the legs of the core and the secondary wound on the other leg4 ,it has neither a vibrator nor a condenser4 ,a plain transformer is shown at ,a in ,fig4 #ba4 ,illustration3 ,fig4 #ba4--,parts for ,transmitting ,set ,no4 #b4 ,a transformer of this kind can be bought either 7a7 unmounted1 that is1 just the bare transformer1 or 7b7 fully mounted1 that is1 fitted with an iron stand1 mounted on an insulating base on which are a pair of primary binding posts1 while the secondary is provided with a safety spark gap4 ,there are three sizes of transformers of this kind made and they are rated at #a_/d1 #a_/b and #a kilowatt1 respectively1 they deliver a secondary current of #i1jjj1 #aa1jjj and #be1jjj volts1 according to size1 and cost #af4jj1 #bb4jj and #cc4jj when fully mounted2 a reduction of #c4jj1 #d4jj and #e4jj is made when they are unmounted4 ,all of these transformers operate on #aaj volt1 #fj cycle current and can be connected directly to the source of alternating current4 ,the ,wireless ,key4--,for this transmitting set a standard wireless key should be used as shown at ,b4 ,it is made about the same as a regular telegraph key but it is much heavier1 the contact points are larger and instead of the current being led through the bearings as in an ordinary key1 it is carried by heavy conductors directly to the contact points4 ,this key is made in three sizes and the first will carry a current of #e amperes,footnote3 ,see ,appendix for definition4 and costs #d4jj1 the second will carry a current of #aj amperes and costs #f4ej1 while the third will carry a current of #bj amperes and costs #g4ej4 ,the ,spark ,gap4--,either a fixed1 a rotary1 or a quenched spark gap can be used with this set1 but the former is seldom used except with spark-coil sets1 as it is very hard to keep the sparks from arcing when large currents are used4 ,a rotary spark gap comprises a wheel1 driven by a small electric motor1 with projecting plugs1 or electrodes1 on it and a pair of stationary plugs on each side of the wheel as shown at ,c4 ,the number of sparks per second can be varied by changing the speed of the wheel and when it is rotated rapidly it sends out signals of a high pitch which are easy to read at the receiving end4 ,a rotary gap with a #aaj-volt motor costs about #be4jj4 ,a quenched spark gap not only eliminates the noise of the ordinary gap but1 when properly designed1 it increases the range of an induction coil set some #bjj per cent4 ,a #a_/d kilowatt quenched gap costs #aj4jj4 ,footnote3 ,see ,appendix for definition4 ,the ,high ,tension ,condenser4--,since1 if you are an amateur1 you can only send out waves that are #bjj meters in length1 you can only use a condenser that has a capacitance of 4#jjg microfarad4 ,footnote3 ,see ,appendix for definition4 ,a sectional high tension condenser like the one described in connection with ,set ,no4 #a can be used with this set but it must have a capacitance of not more than 4#jjg microfarad4 ,a condenser of this value for a #a_/d-kilowatt transformer costs #g4jj2 for a #a_/b-kilowatt transformer #ad4jj1 and for a #a-kilowatt transformer #ba4jj4 ,see ,e1 ,fig4 #ai4 ,the ,oscillation ,transformer4--,with an oscillation transformer you can tune much more sharply than with a single inductance coil tuner4 ,the primary coil is formed of #f turns of copper strip1 or ,no4 #i copper wire1 and the secondary is formed of #i turns of strip1 or wire4 ,the primary coil1 which is the outside coil1 is hinged to the base and can be raised or lowered like the lid of a box4 ,when it is lowered the primary and secondary coils are in the same plane and when it is raised the coils set at an angle to each other4 ,it is shown at ,d and costs #e4jj4 ,connecting ,up the ,apparatus4 ,for ,alternating ,current4--,screw the key to the table about the middle of it and near the front edge2 place the high tension condenser back of it and the oscillation transformer back of the latter2 set the alternating current transformer to the left of the oscillation transformer and place the rotary or quenched spark gap in front of it4 ,now bring a pair of ,no4 #ab or #ad insulated wires from the #aaj volt lighting leads and connect them with a single-throw1 double-pole switch2 connect one pole of the switch with one of the posts of the primary coil of the alternating power transformer and connect the other post of the latter with one of the posts of your key1 and the other post of this with the other pole of the switch4 ,now connect the motor of the rotary spark gap to the power circuit and put a single-pole1 single-throw switch in the motor circuit1 all of which is shown at ,a in ,fig4 #bb4 ,illustration3 7,a7 ,fig4 #bb4--,top ,view of ,apparatus ,layout for ,sending ,set ,no4 #b4 ,illustration3 7,b7 ,fig4 #bb4--,wiring ,diagram for ,sending ,set ,no4 #b4 ,next connect the posts of the secondary coil to the posts of the rotary or quenched spark gap and connect one post of the latter to one post of the condenser1 the other post of this to the post of the primary coil of the oscillation transformer1 which is the inside coil1 and the clip of the primary coil to the other spark gap post4 ,this completes the closed oscillation circuit4 ,finally connect the post of the secondary coil of the oscillation transformer to the ground and the clip of it to the wire leading to the aerial when you are ready to tune the set4 ,a wiring diagram of the connections is shown at ,b4 ,for ,direct ,current4--,where you have #aaj volt direct current you must connect in an electrolytic interrupter4 ,this interrupter1 which is shown at ,a and ,b in ,fig4 #bc1 consists of 7#a7 a jar filled with a solution of #a part of sulphuric acid and #i parts of water1 7#b7 a lead electrode having a large surface fastened to the cover of surface that sets in a porcelain sleeve and whose end rests on the bottom of the jar4 ,illustration3 ,fig4 #bc4--,using #aaj ,volt ,direct ,current with an ,alternating ,current ,transformer4 ,when these electrodes are connected in series with the primary of a large spark coil or an alternating current transformer1 see ,c1 and a direct current of from #dj to #aaj volts is made to pass through it1 the current is made and broken from #a1jjj to #aj1jjj times a minute4 ,by raising or lowering the sleeve1 thus exposing more or less of the platinum1 or alloy point1 the number of interruptions per minute can be varied at will4 ,as the electrolytic interrupter will only operate in one direction1 you must connect it with its platinum1 or alloy anode1 to the or positive power lead and the lead cathode to the - or negative power lead4 ,you can find out which is which by connecting in the interrupter and trying it1 or you can use a polarity indicator4 ,an electrolytic interrupter can be bought for as little as #c4jj4 ,how to ,adjust ,your ,transmitter4 ,tuning ,with a ,hot ,wire ,ammeter4--,a transmitter can be tuned in two different ways and these are3 7#a7 by adjusting the length of the spark gap and the tuning coil so that the greatest amount of energy is set up in the oscillating circuits1 and 7#b7 by adjusting the apparatus so that it will send out waves of a given length4 ,to adjust the transmitter so that the circuits will be in tune you should have a hot wire ammeter1 or radiation ammeter1 as it is called1 which is shown in ,fig4 #bd4 ,it consists of a thin platinum wire through which the high-frequency currents surge and these heat it2 the expansion and contraction of the wire moves a needle over a scale marked off into fractions of an ampere4 ,when the spark gap and tuning coil of your set are properly adjusted1 the needle will swing farthest to the right over the scale and you will then know that the aerial wire system1 or open oscillation circuit1 and the closed oscillation circuit are in tune and radiating the greatest amount of energy4 ,illustration3 ,fig4 #bd4--,principle of the ,hot ,wire ,ammeter4 ,to ,send ,out a #bjj ,meter ,wave ,length4--,if you are using a condenser having a capacitance of 4#jjg microfarad1 which is the largest capacity value that the ,government will allow an amateur to use1 then if you have a hot wire ammeter in your aerial and tune the inductance coil or coils until the ammeter shows the largest amount of energy flowing through it you will know that your transmitter is tuned and that the aerial is sending out waves whose length is #bjj meters4 ,to tune to different wave lengths you must have a wave-meter4 ,the ,use of the ,aerial ,switch4--,where you intend to install both a transmitter and a receptor you will need a throwover switch1 or aerial switch1 as it is called4 ,an ordinary double-pole1 double-throw switch1 as shown at ,a in ,fig4 #be1 can be used1 or a switch made especially for the purpose as at ,b is handier because the arc of the throw is much less4 ,illustration3 ,fig4 #be4--,kinds of ,aerial ,switches4 ,aerial ,switch for a ,complete ,sending and ,receiving ,set4--,you can buy a double-pole1 double-throw switch mounted on a porcelain base for about #ge cents and this will serve for ,set ,no4 #a4 ,screw this switch on your table between the sending and receiving sets and then connect one of the middle posts of it with the ground wire and the other middle post with the lightning switch which connects with the aerial4 ,connect the post of the tuning coil with one of the end posts of the switch and the clip of the tuning coil with the other and complementary post of the switch4 ,this done1 connect one of the opposite end posts of the switch to the post of the receiving tuning coil and connect the sliding contact of the latter with the other and complementary post of the switch as shown in ,fig4 #bf4 ,illustration3 ,fig4 #bf4--,wiring ,diagram for ,complete ,sending and ,receiving ,set ,no4 #a4 ,connecting in the ,lightning ,switch4--,the aerial wire connects with the middle post of the lightning switch1 while one of the end posts lead to one of the middle posts of the aerial switch4 ,the other end post of the lightning switch leads to a separate ground outside the building1 as the wiring diagrams ,figs4 #bf and #bg show4 ,illustration3 ,fig4 #bg4--,wiring ,diagram for ,complete ,sending and ,receiving ,set ,no4 #b4 ,,chapter ,v ,,electricity ,,simply ,,explained ,it is easy to understand how electricity behaves and what it does if you get the right idea of it at the start4 ,in the first place1 if you will think of electricity as being a fluid like water its fundamental actions will be greatly simplified4 ,both water and electricity may be at rest or in motion4 ,when at rest1 under certain conditions1 either one will develop pressure1 and this pressure when released will cause them to flow through their respective conductors and thus produce a current4 ,electricity at ,rest and in ,motion4--,any wire or a conductor of any kind can be charged with electricity1 but a ,leyden jar1 or other condenser1 is generally used to hold an electric charge because it has a much larger capacitance1 as its capacity is called1 than a wire4 ,as a simple analogue of a condenser1 suppose you have a tank of water raised above a second tank and that these are connected together by means of a pipe with a valve in it1 as shown at ,a in ,fig4 #bh4 ,illustration3 ,fig4 #bh4--,water ,analogue for ,electric ,pressure4 ,illustration3 original ,underwood and ,underwood4 ,first ,wireless ,college in the ,world1 at ,tufts ,college1 ,mass4 ,now if you fill the upper tank with water and the valve is turned off1 no water can flow into the lower tank but there is a difference of pressure between them1 and the moment you turn the valve on a current of water will flow through the pipe4 ,in very much the same way when you have a condenser charged with electricity the latter will be under pressure1 that is1 a difference of potential will be set up1 for one of the sheets of metal will be charged positively and the other one1 which is insulated from it1 will be charged negatively1 as shown at ,b4 ,on closing the switch the opposite charges rush together and form a current which flows to and fro between the metal plates4 ,footnote3 ,strictly speaking it is the difference of potential that sets up the electromotive force4 ,the ,electric ,current and ,its ,circuit4--,just as water flowing through a pipe has quantity and pressure back of it and the pipe offers friction to it which tends to hold back the water1 so1 likewise1 does electricity flowing in a circuit have3 7#a7 quantity1 or current strength1 or just current1 as it is called for short1 or amperage1 and 7#b7 pressure1 or potential difference1 or electromotive force1 or voltage1 as it is variously called1 and the wire1 or circuit1 in which the current is flowing has 7#c7 resistance which tends to hold back the current4 ,a definite relation exists between the current and its electromotive force and also between the current1 electromotive force and the resistance of the circuit2 and if you will get this relationship clearly in your mind you will have a very good insight into how direct and alternating currents act4 ,to keep a quantity of water flowing in a loop of pipe1 which we will call the circuit1 pressure must be applied to it and this may be done by a rotary pump as shown at ,a in ,fig4 #bi2 in the same way1 to keep a quantity of electricity flowing in a loop of wire1 or circuit1 a battery1 or other means for generating electric pressure must be used1 as shown at ,b4 ,illustration3 ,fig4 #bi4--,water ,analogues for ,direct and ,alternating ,currents4 ,if you have a closed pipe connected with a piston pump1 as at ,c1 as the piston moves to and fro the water in the pipe will move first one way and then the other4 ,so also when an alternating current generator is connected to a wire circuit1 as at ,d1 the current will flow first in one direction and then in the other1 and this is what is called an alternating current4 ,current and the ,ampere4--,the amount of water flowing in a closed pipe is the same at all parts of it and this is also true of an electric current1 in that there is exactly the same quantity of electricity at one point of the circuit as there is at any other4 ,the amount of electricity1 or current1 flowing in a circuit in a second is measured by a unit called the ampere1 ,footnote3 ,for definition of ampere see ,appendix4 and it is expressed by the symbol ,i4 ,footnote3 ,this is because the letter ,c is used for the symbol of capacitance ,just to give you an idea of the quantity of current an ampere is we will say that a dry cell when fresh gives a current of about #bj amperes4 ,to measure the current in amperes an instrument called an ammeter is used1 as shown at ,a in ,fig4 #cj1 and this is always connected in series with the line1 as shown at ,b4 ,illustration3 ,fig4 #cj4--;,how the ,ammeter and ,voltmeter are ,used4 ,electromotive ,force and the ,volt4--,when you have a pipe filled with water or a circuit charged with electricity and you want to make them flow you must use a pump in the first case and a battery or a dynamo in the second case4 ,it is the battery or dynamo that sets up the electric pressure as the circuit itself is always charged with electricity4 ,the more cells you connect together in series the greater will be the electric pressure developed and the more current it will move along just as the amount of water flowing in a pipe can be increased by increasing the pressure of the pump4 ,the unit of electromotive force is the volt1 and this is the electric pressure which will force a current of #a ampere through a resistance of #a ohm2 it is expressed by the symbol ,e4 ,a fresh dry cell will deliver a current of about #a4e volts4 ,to measure the pressure of a current in volts an instrument called a voltmeter is used1 as shown at ,c in ,fig4 #cj1 and this is always connected across the circuit1 as shown at ,d4 ,resistance and the ,ohm4--,just as a water pipe offers a certain amount of resistance to the flow of water through it1 so a circuit opposes the flow of electricity in it and this is called resistance4 ,further1 in the same way that a small pipe will not allow a large amount of water to flow through it1 so1 too1 a thin wire limits the flow of the current in it4 ,if you connect a resistance coil in a circuit it acts in the same way as partly closing the valve in a pipe1 as shown at ,a and ,b in ,fig4 #ca4 ,the resistance of a circuit is measured by a unit called the ohm1 and it is expressed by the symbol ,r4 ,a ,no4 #aj1 ,brown and ,sharpe gauge soft copper wire1 #a1jjj feet long1 has a resistance of about #a ohm4 ,to measure the resistance of a circuit an apparatus called a resistance bridge is used4 ,the resistance of a circuit can1 however1 be easily calculated1 as the following shows4 ,illustration3 ,fig4 #ca4--,water ,valve ,analogue of ,electric ,resistance4 ,a- a valve limits the flow of water4 ,b- a resistance limits the flow of current4 ,what ,ohm's ,law ,is4--,if1 now1 7#a7 you know what the current flowing in a circuit is in amperes1 and the electromotive force1 or pressure1 is in volts1 you can then easily find what the resistance is in ohms of the circuit in which the current is flowing by this formula3 ,volts ,e --------- ,ohms1 or --- ,r ,amperes ,i ,that is1 if you divide the current in amperes by the electromotive force in volts the quotient will give you the resistance in ohms4 ,or 7#b7 if you know what the electromotive force of the current is in volts and the resistance of the circuit is in ohms then you can find what the current flowing in the circuit is in amperes1 thus3 ,volts ,e ----- ,amperes1 or --- ,i ,ohms ,r ,that is1 by dividing the resistance of the circuit in ohms1 by the electromotive force of the current you will get the amperes flowing in the circuit4 ,finally 7#c7 if you know what the resistance of the circuit is in ohms and the current is in amperes then you can find what the electromotive force is in volts since3 ,ohms x ,amperes ,volts1 or ,r x ,i ,e ,that is1 if you multiply the resistance of the circuit in ohms by the current in amperes the result will give you the electromotive force in volts4 ,from this you will see that if you know the value of any two of the constants you can find the value of the unknown constant by a simple arithmetical process4 ,this relation between these three constants is known as ,ohm's ,law and as they are very important you should memorize them4 ,what the ,watt and ,kilowatt ,are4--,just as horsepower or ,h4,p41 is the unit of work that steam has done or can do1 so the watt is the unit of work that an electric current has done or can do4 ,to find the watts a current develops you need only to multiply the amperes by the volts4 ,there are #gdf watts to #a horsepower1 and #a1jjj watts are equal to #a kilowatt4 ,electromagnetic ,induction4--,to show that a current of electricity sets up a magnetic field around it you have only to hold a compass over a wire whose ends are connected with a battery when the needle will swing at right angles to the length of the wire4 ,by winding an insulated wire into a coil and connecting the ends of the latter with a battery you will find1 if you test it with a compass1 that the coil is magnetic4 ,this is due to the fact that the energy of an electric current flowing in the wire is partly changed into magnetic lines of force which rotate at right angles about it as shown at ,a in ,fig4 #cb4 ,the magnetic field produced by the current flowing in the coil is precisely the same as that set up by a permanent steel magnet4 ,conversely1 when a magnetic line of force is set up a part of its energy goes to make up electric currents which whirl about in a like manner1 as shown at ,b4 ,illustration3 7,a7 and 7,b7 ,fig4 #cb4--;,how an ,electric ,current is ,changed into ,magnetic ,lines of ,force and ,these into an ,electric ,current4 ,illustration3 7,c7 and 7,d7 ,fig4 #cb4--;,how an ,electric ,current ,sets up a ,magnetic ,field4 ,self-induction or ,inductance4--,when a current is made to flow in a coil of wire the magnetic lines of force produced are concentrated1 as at ,c1 just as a lens concentrates rays of light1 and this forms an intense magnetic field1 as it is called4 ,now if a bar of soft iron is brought close to one end of the coil of wire1 or1 better still1 if it is pushed into the coil1 it will be magnetized by electromagnetic induction1 see ,d1 and it will remain a magnet until the current is cut off4 ,mutual ,induction4--,when two loops of wire1 or better1 two coils of wire1 are placed close together the electromagnetic induction between them is reactive1 that is1 when a current is made to flow through one of the coils closed magnetic lines of force are set up and when these cut the other loop or turns of wire of the other coil1 they in turn produce electric currents in it4 ,it is the mutual induction that takes place between two coils of wire which makes it possible to transform low voltage currents from a battery or a #aaj volt source of current into high pressure currents1 or high potential currents1 as they are called1 by means of a spark coil or a transformer1 as well as to step up and step down the potential of the high frequency currents that are set up in sending and receiving oscillation transformers4 ,soft iron cores are not used in oscillation inductance coils and oscillation transformers for the reason that the frequency of the current is so high the iron would not have time to magnetize and demagnetize and so would not help along the mutual induction to any appreciable extent4 ,high-,frequency ,currents4--,high frequency currents1 or electric oscillations as they are called1 are currents of electricity that surge to and fro in a circuit a million times1 more or less1 per second4 ,currents of such high frequencies will oscillate1 that is1 surge to and fro1 in an open circuit1 such as an aerial wire system1 as well as in a closed circuit4 ,now there is only one method by which currents of high frequency1 or radio-frequency1 as they are termed1 can be set up by spark transmitters1 and this is by discharging a charged condenser through a circuit having a small resistance4 ,to charge a condenser a spark coil or a transformer is used and the ends of the secondary coil1 which delivers the high potential alternating current1 are connected with the condenser4 ,to discharge the condenser automatically a spark1 or an arc1 or the flow of electrons in a vacuum tube1 is employed4 ,constants of an ,oscillation ,circuit4--,an oscillation circuit1 as pointed out before1 is one in which high frequency currents surge or oscillate4 ,now the number of times a high frequency current will surge forth and back in a circuit depends upon three factors of the latter and these are called the constants of the circuit1 namely3 7#a7 its capacitance1 7#b7 its inductance and 7#c7 its resistance4 ,what ,capacitance ,is4--,the word capacitance means the electrostatic capacity of a condenser or a circuit4 ,the capacitance of a condenser or a circuit is the quantity of electricity which will raise its pressure1 or potential1 to a given amount4 ,the capacitance of a condenser or a circuit depends on its size and form and the voltage of the current that is charging it4 ,the capacitance of a condenser or a circuit is directly proportional to the quantity of electricity that will keep the charge at a given potential4 ,the farad1 whose symbol is ,m1 is the unit of capacitance and a condenser or a circuit to have a capacitance of one farad must be of such size that one coulomb1 which is the unit of electrical quantity1 will raise its charge to a potential of one volt4 ,since the farad is far too large for practical purposes a millionth of a farad1 or microfarad1 whose symbol is mfd41 is used4 ,what ,inductance ,is4--,under the sub-caption of ,self-induction and ,inductance in the beginning of this chapter it was shown that it was the inductance of a coil that makes a current flowing through it produce a strong magnetic field1 and here1 as one of the constants of an oscillation circuit1 it makes a high-frequency current act as though it possessed inertia4 ,inertia is that property of a material body that requires time and energy to set in motion1 or stop4 ,inductance is that property of an oscillation circuit that makes an electric current take time to start and time to stop4 ,because of the inductance1 when a current flows through a circuit it causes the electric energy to be absorbed and changes a large part of it into magnetic lines of force4 ,where high frequency currents surge in a circuit the inductance of it becomes a powerful factor4 ,the practical unit of inductance is the henry and it is represented by the symbol ,l4 ,what ,resistance ,is4--,the resistance of a circuit to high-frequency currents is different from that for low voltage direct or alternating currents1 as the former do not sink into the conductor to nearly so great an extent2 in fact1 they stick practically to the surface of it1 and hence their flow is opposed to a very much greater extent4 ,the resistance of a circuit to high frequency currents is generally found in the spark gap1 arc gap1 or the space between the electrodes of a vacuum tube4 ,the unit of resistance is1 as stated1 the ohm1 and its symbol is ,r4 ,the ,effect of ,capacitance1 ,inductance and ,resistance on ,electric ,oscillations4--,if an oscillation circuit in which high frequency currents surge has a large resistance1 it will so oppose the flow of the currents that they will be damped out and reach zero gradually1 as shown at ,a in ,fig4 #cc4 ,but if the resistance of the circuit is small1 and in wireless circuits it is usually so small as to be negligible1 the currents will oscillate1 until their energy is damped out by radiation and other losses1 as shown at ,b4 ,illustration3 ,fig4 #cc4--,the ,effect of ,resistance on the ,discharge of an ,electric ,current4 ,as the capacitance and the inductance of the circuit1 which may be made of any value1 that is amount1 you wish1 determines the time period1 that is1 the length of time for a current to make one complete oscillation1 it must be clear that by varying the values of the condenser and the inductance coil you can make the high frequency current oscillate as fast or as slow as you wish within certain limits4 ,where the electric oscillations that are set up are very fast1 the waves sent out by the aerial will be short1 and1 conversely1 where the oscillations are slow the waves emitted will be long4 ,,chapter ,,vi ,,how ,,the ,,transmitting ,,and ,,receiving ,,sets ,,work ,the easiest way to get a clear conception of how a wireless transmitter sends out electric waves and how a wireless receptor receives them is to take each one separately and follow3 7#a7 in the case of the transmitter1 the transformation of the low voltage direct1 or alternating current into high potential alternating currents2 then find out how these charge the condenser1 how this is discharged by the spark gap and sets up high-frequency currents in the oscillation circuits2 then 7#b7 in the case of the receptor1 to follow the high frequency currents that are set up in the aerial wire and learn how they are transformed into oscillations of lower potential when they have a larger current strength1 how these are converted into intermittent direct currents by the detector and which then flow into and operate the telephone receiver4 ,how ,transmitting ,set ,no4 #a ,works4 ,the ,battery and ,spark ,coil ,circuit4--,when you press down on the knob of the key the silver points of it make contact and this closes the circuit2 the low voltage direct current from the battery now flows through the primary coil of the spark coil and this magnetizes the soft iron core4 ,the instant it becomes magnetic it pulls the spring of the vibrator over to it and this breaks the circuit2 when this takes place the current stops flowing through the primary coil2 this causes the core to lose its magnetism when the vibrator spring flies back and again makes contact with the adjusting screw2 then the cycle of operations is repeated4 ,a condenser is connected across the contact points of the vibrator since this gives a much higher voltage at the ends of the secondary coil than where the coil is used without it2 this is because3 7#a7 the self-induction of the primary coil makes the pressure of the current rise and when the contact points close the circuit again it discharges through the primary coil1 and 7#b7 when the break takes place the current flows into the condenser instead of arcing across the contact points4 ,changing the ,primary ,spark ,coil ,current ,into ,secondary ,currents4--,now every time the vibrator contact points close the primary circuit the electric current in the primary coil is changed into closed magnetic lines of force and as these cut through the secondary coil they set up in it a momentary current in one direction4 ,then the instant the vibrator points break apart the primary circuit is opened and the closed magnetic lines of force contract and as they do so they cut the turns of wire in the secondary coil in the opposite direction and this sets up another momentary current in the secondary coil in the other direction4 ,the result is that the low voltage direct current of the battery is changed into alternating currents whose frequency is precisely that of the spring vibrator1 but while the frequency of the currents is low their potential1 or voltage1 is enormously increased4 ,what ,ratio of ,transformation ,means4--,to make a spark coil step up the low voltage direct current into high potential alternating current the primary coil is wound with a couple of layers of thick insulated copper wire and the secondary is wound with a thousand1 more or less1 number of turns with very fine insulated copper wire4 ,if the primary and secondary coils were wound with the same number of turns of wire then the pressure1 or voltage1 of the secondary coil at its terminals would be the same as that of the current which flowed through the primary coil4 ,under these conditions the ratio of transformation1 as it is called1 would be unity4 ,the ratio of transformation is directly proportional to the number of turns of wire on the primary and secondary coils and1 since this is the case1 if you wind #aj turns of wire on the primary coil and #a1jjj turns of wire on the secondary coil then you will get #ajj times as high a pressure1 or voltage1 at the terminals of the secondary as that which you caused to flow through the primary coil1 but1 naturally1 the current strength1 or amperage1 will be proportionately decreased4 ,the ,secondary ,spark ,coil ,circuit4--,this includes the secondary coil and the spark gap which are connected together4 ,when the alternating1 but high potential1 currents which are developed by the secondary coil1 reach the balls1 or electrodes1 of the spark gap the latter are alternately charged positively and negatively4 ,now take a given instant when one electrode is charged positively and the other one is charged negatively1 then when they are charged to a high enough potential the electric strain breaks down the air gap between them and the two charges rush together as described in the chapter before this one in connection with the discharge of a condenser4 ,when the charges rush together they form a current which burns out the air in the gap and this gives rise to the spark1 and as the heated gap between the two electrodes is a very good conductor the electric current surges forth and back with high frequency1 perhaps a dozen times1 before the air replaces that which has burned out4 ,it is the inrushing air to fill the vacuum of the gap that makes the crackling noise which accompanies the discharge of the electric spark4 ,in this way then electric oscillations of the order of a million1 more or less1 are produced and if an aerial and a ground wire are connected to the spark balls1 or electrodes1 the oscillations will surge up and down it and the energy of these in turn1 are changed into electric waves which travel out into space4 ,an open circuit transmitter of this kind will send out waves that are four times as long as the aerial itself1 but as the waves it sends out are strongly damped the ,government will not permit it to be used4 ,the ,closed ,oscillation ,circuit4--,by using a closed oscillation circuit the transmitter can be tuned to send out waves of a given length and while the waves are not so strongly damped more current can be sent into the aerial wire system4 ,the closed oscillation circuit consists of3 7#a7 a spark gap1 7#b7 a condenser and 7#c7 an oscillation transformer4 ,the high potential alternating current delivered by the secondary coil not only charges the spark gap electrodes which necessarily have a very small capacitance1 but it charges the condenser which has a large capacitance and the value of which can be changed at will4 ,now when the condenser is fully charged it discharges through the spark gap and then the electric oscillations set up surge to and fro through the closed circuit4 ,as a closed circuit is a very poor radiator of energy1 that is1 the electric oscillations are not freely converted into electric waves by it1 they surge up to1 and through the aerial wire2 now as the aerial wire is a good radiator nearly all of the energy of the electric oscillations which surge through it are converted into electric waves4 ,how ,transmitting ,set ,no4 #b ,works4 ,with ,alternating ,current4 ,the operation of a transmitting set that uses an alternating current transformer1 or power transformer1 as it is sometimes called1 is even more simple than one using a spark coil4 ,the transformer needs no vibrator when used with alternating current4 ,the current from a generator flows through the primary coil of the transformer and the alternations of the usual lighting current is #fj cycles per second4 ,this current sets up an alternating magnetic field in the core of the transformer and as these magnetic lines of force expand and contract they set up alternating currents of the same frequency but of much higher voltage at the terminals of the secondary coil according to the ratio of the primary and secondary turns of wire as explained under the sub-caption of ,ratio of ,transformation4 ,with ,direct ,current4--,when a #aaj volt direct current is used to energize the power transformer an electrolytic interruptor is needed to make and break the primary circuit1 just as a vibrator is needed for the same purpose with a spark coil4 ,when the electrodes are connected in series with the primary coil of a transformer and a source of direct current having a potential of #dj to #aaj volts1 bubbles of gas are formed on the end of the platinum1 or alloy anode1 which prevent the current from flowing until the bubbles break and then the current flows again1 in this way the current is rapidly made and broken and the break is very sharp4 ,where this type of interrupter is employed the condenser that is usually shunted around the break is not necessary as the interrupter itself has a certain inherent capacitance1 due to electrolytic action1 and which is called its electrolytic capacitance1 and this is large enough to balance the self-induction of the circuit since the greater the number of breaks per minute the smaller the capacitance required4 ,the ,rotary ,spark ,gap4--,in this type of spark gap the two fixed electrodes are connected with the terminals of the secondary coil of the power transformer and also with the condenser and primary of the oscillation transformer4 ,now whenever any pair of electrodes on the rotating disk are in a line with the pair of fixed electrodes a spark will take place1 hence the pitch of the note depends on the speed of the motor driving the disk4 ,this kind of a rotary spark-gap is called non-synchronous and it is generally used where a #fj cycle alternating current is available but it will work with other higher frequencies4 ,the ,quenched ,spark ,gap4--,if you strike a piano string a single quick blow it will continue to vibrate according to its natural period4 ,this is very much the way in which a quenched spark gap sets up oscillations in a coupled closed and open circuit4 ,the oscillations set up in the primary circuit by a quenched spark make only three or four sharp swings and in so doing transfer all of their energy over to the secondary circuit1 where it will oscillate some fifty times or more before it is damped out1 because the high frequency currents are not forced1 but simply oscillate to the natural frequency of the circuit4 ,for this reason the radiated waves approach somewhat the condition of continuous waves1 and so sharper tuning is possible4 ,the ,oscillation ,transformer4--,in this set the condenser in the closed circuit is charged and discharged and sets up oscillations that surge through the closed circuit as in ,set ,no4 #a4 ,in this set1 however1 an oscillation transformer is used and as the primary coil of it is included in the closed circuit the oscillations set up in it produce strong oscillating magnetic lines of force4 ,the magnetic field thus produced sets up in turn electric oscillations in the secondary coil of the oscillation transformer and these surge through the aerial wire system where their energy is radiated in the form of electric waves4 ,the great advantage of using an oscillation transformer instead of a simple inductance coil is that the capacitance of the closed circuit can be very much larger than that of the aerial wire system4 ,this permits more energy to be stored up by the condenser and this is impressed on the aerial when it is radiated as electric waves4 ,how ,receiving ,set ,no4 ,i ,works4--,when the electric waves from a distant sending station impinge on the wire of a receiving aerial their energy is changed into electric oscillations that are of exactly the same frequency 7assuming the receptor is tuned to the transmitter7 but whose current strength 7amperage7 and potential 7voltage7 are very small4 ,these electric waves surge through the closed circuit but when they reach the crystal detector the contact of the metal point on the crystal permits more current to flow through it in one direction than it will allow to pass in the other direction4 ,for this reason a crystal detector is sometimes called a rectifier1 which it really is4 ,thus the high frequency currents which the steel magnet cores of the telephone receiver would choke off are changed by the detector into intermittent direct currents which can flow through the magnet coils of the telephone receiver4 ,since the telephone receiver chokes off the oscillations1 a small condenser can be shunted around it so that a complete closed oscillation circuit is formed and this gives better results4 ,when the intermittent rectified current flows through the coils of the telephone receiver it energizes the magnet as long as it lasts1 when it is de-energized2 this causes the soft iron disk1 or diaphragm as it is called1 which sets close to the ends of the poles of the magnet1 to vibrate2 and this in turn gives forth sounds such as dots and dashes1 speech or music1 according to the nature of the electric waves that sent them out at the distant station4 ,how ,receiving ,set ,no4 #b ,works4--,when the electric oscillations that are set up by the incoming electric waves on the aerial wire surge through the primary coil of the oscillation transformer they produce a magnetic field and as the lines of force of the latter cut the secondary coil1 oscillations of the same frequency are set up in it4 ,the potential 7voltage7 of these oscillations are1 however1 stepped down in the secondary coil and1 hence1 their current strength 7amperes7 is increased4 ,the oscillations then flow through the closed circuit where they are rectified by the crystal detector and transformed into sound waves by the telephone receiver as described in connection with ,set ,no4 #a4 ,the variable condenser shunted across the closed circuit permits finer secondary tuning to be done than is possible without it4 ,where you are receiving continuous waves from a wireless telephone transmitter 7speech or music7 you have to tune sharper than is possible with the tuning coil alone and to do this a variable condenser connected in parallel with the secondary coil is necessary4 ,,chapter ,,vii ,,mechanical ,,and ,,electrical ,,tuning ,there is a strikingly close resemblance between sound waves and the way they are set up in the air by a mechanically vibrating body1 such as a steel spring or a tuning fork1 and electric waves and the way they are set up in the ether by a current oscillating in a circuit4 ,as it is easy to grasp the way that sound waves are produced and behave something will be told about them in this chapter and also an explanation of how electric waves are produced and behave and thus you will be able to get a clear understanding of them and of tuning in general4 ,damped and ,sustained ,mechanical ,vibrations4--,if you will place one end of a flat steel spring in a vice and screw it up tight as shown at ,a in ,fig4 #cd1 and then pull the free end over and let it go it will vibrate to and fro with decreasing amplitude until it comes to rest as shown at ,b4 ,when you pull the spring over you store up energy in it and when you let it go the stored up energy is changed into energy of motion and the spring moves forth and back1 or vibrates as we call it1 until all of its stored up energy is spent4 ,illustration3 ,fig4 #cd4--;,damped and ,sustained ,mechanical ,vibrations4 ,if it were not for the air surrounding it and other frictional losses1 the spring would vibrate for a very long time as the stored up energy and the energy of motion would practically offset each other and so the energy would not be used up4 ,but as the spring beats the air the latter is sent out in impulses and the conversion of the vibrations of the spring into waves in the air soon uses up the energy you have imparted to it and it comes to rest4 ,in order to send out continuous waves in the air instead of damped waves as with a flat steel spring you can use an electric driven tuning fork1 see ,c1 in which an electromagnet is fixed on the inside of the prongs and when this is energized by a battery current the vibrations of the prongs of the fork are kept going1 or are sustained1 as shown in the diagram at ,d4 ,damped and ,sustained ,electric ,oscillations4--,the vibrating steel spring described above is a very good analogue of the way that damped electric oscillations which surge in a circuit set up and send out periodic electric waves in the ether while the electric driven tuning fork just described is likewise a good analogue of how sustained oscillations surge in a circuit and set up and send out continuous electric waves in the ether as the following shows4 ,now the inductance and resistance of a circuit such as is shown at ,a in ,fig4 #ce1 slows down1 and finally damps out entirely1 the electric oscillations of the high frequency currents1 see ,b1 where these are set up by the periodic discharge of a condenser1 precisely as the vibrations of the spring are damped out by the friction of the air and other resistances that act upon it4 ,as the electric oscillations surge to and fro in the circuit it is opposed by the action of the ether which surrounds it and electric waves are set up in and sent out through it and this transformation soon uses up the energy of the current that flows in the circuit4 ,illustration3 ,fig4 #ce4--;,damped and ,sustained ,electric ,oscillations4 ,to send out continuous waves in the ether such as are needed for wireless telephony instead of damped waves which are1 at the present writing1 generally used for wireless telegraphy1 an electric oscillation arc or a vacuum tube oscillator must be used1 see ,c1 instead of a spark gap4 ,where a spark gap is used the condenser in the circuit is charged periodically and with considerable lapses of time between each of the charging processes1 when1 of course1 the condenser discharges periodically and with the same time element between them4 ,where an oscillation arc or a vacuum tube is used the condenser is charged as rapidly as it is discharged and the result is the oscillations are sustained as shown at ,d4 ,about ,mechanical ,tuning4--,a tuning fork is better than a spring or a straight steel bar for setting up mechanical vibrations4 ,as a matter of fact a tuning fork is simply a steel bar bent in the middle so that the two ends are parallel4 ,a handle is attached to middle point of the fork so that it can be held easily and which also allows it to vibrate freely1 when the ends of the prongs alternately approach and recede from one another4 ,when the prongs vibrate the handle vibrates up and down in unison with it1 and imparts its motion to the sounding box1 or resonance case as it is sometimes called1 where one is used4 ,if1 now1 you will mount the fork on a sounding box which is tuned so that it will be in resonance with the vibrations of the fork there will be a direct reinforcement of the vibrations when the note emitted by it will be augmented in strength and quality4 ,this is called simple resonance4 ,further1 if you mount a pair of forks1 each on a separate sounding box1 and have the forks of the same size1 tone and pitch1 and the boxes synchronized1 that is1 tuned to the same frequency of vibration1 then set the two boxes a foot or so apart1 as shown at ,a in ,fig4 #cf1 when you strike one of the forks with a rubber hammer it will vibrate with a definite frequency and1 hence1 send out sound waves of a given length4 ,when the latter strike the second fork the impact of the molecules of air of which the sound waves are formed will set its prongs to vibrating and it will1 in turn1 emit sound waves of the same length and this is called sympathetic resonance1 or as we would say in wireless the forks are in tune4 ,illustration3 ,fig4 #cf4--,sound ,wave and ,electric ,wave ,tuned ,senders and ,receptors4 ,a - variable tuning forks for showing sound wave tuning4 ,b - variable oscillation circuits for showing electric wave tuning4 ,tuning forks are made with adjustable weights on their prongs and by fixing these to different parts of them the frequency with which the forks vibrate can be changed since the frequency varies inversely with the square of the length and directly with the thickness ,footnote3 ,this law is for forks having a rectangular cross-section4 ,those having a round cross-section vary as the radius4 of the prongs4 ,now by adjusting one of the forks so that it vibrates at a frequency of1 say1 #af per second and adjusting the other fork so that it vibrates at a frequency of1 say1 #ah or #bj per second1 then the forks will not be in tune with each other and1 hence1 if you strike one of them the other will not respond4 ,but if you make the forks vibrate at the same frequency1 say #af1 #bj or #bd per second1 when you strike one of them the other will vibrate in unison with it4 ,about ,electric ,tuning4--,electric resonance and electric tuning are very like those of acoustic resonance and acoustic tuning which ,i have just described4 ,just as acoustic resonance may be simple or sympathetic so electric resonance may be simple or sympathetic4 ,simple acoustic resonance is the direct reinforcement of a simple vibration and this condition is had when a tuning fork is mounted on a sounding box4 ,in simple electric resonance an oscillating current of a given frequency flowing in a circuit having the proper inductance and capacitance may increase the voltage until it is several times greater than its normal value4 ,tuning the receptor circuits to the transmitter circuits are examples of sympathetic electric resonance4 ,as a demonstration if you have two ,leyden jars 7capacitance7 connected in circuit with two loops of wire 7inductance7 whose inductance can be varied as shown at ,b in ,fig4 #cf1 when you make a spark pass between the knobs of one of them by means of a spark coil then a spark will pass in the gap of the other one provided the inductance of the two loops of wire is the same4 ,but if you vary the inductance of the one loop so that it is larger or smaller than that of the other loop no spark will take place in the second circuit4 ,when a tuning fork is made to vibrate it sends out waves in the air1 or sound waves1 in all directions and just so when high frequency currents surge in an oscillation circuit they send out waves in the ether1 or electric waves1 that travel in all directions4 ,for this reason electric waves from a transmitting station cannot be sent to one particular station1 though they do go further in one direction than in another1 according to the way your aerial wire points4 ,since the electric waves travel out in all directions any receiving set properly tuned to the wave length of the sending station will receive the waves and the only limit on your ability to receive from high-power stations throughout the world depends entirely on the wave length and sensitivity of your receiving set4 ,as for tuning1 just as changing the length and the thickness of the prongs of a tuning fork varies the frequency with which it vibrates and1 hence1 the length of the waves it sends out1 so1 too1 by varying the capacitance of the condenser and the inductance of the tuning coil of the transmitter the frequency of the electric oscillations set up in the circuit may be changed and1 consequently1 the length of the electric waves they send out4 ,likewise1 by varying the capacitance and the inductance of the receptor the circuits can be tuned to receive incoming electric waves of whatever length within the limitation of the apparatus4 ,,chapter ,,viii ,a ,,simple ,,vacuum ,,tube ,,detector ,,receiving ,,set ,while you can receive dots and dashes from spark wireless telegraph stations and hear spoken words and music from wireless telephone stations with a crystal detector receiving set such as described in ,chapter ,,iii1 you can get stations that are much farther away and hear them better with a vacuum tube detector receiving set4 ,though the vacuum tube detector requires two batteries to operate it and the receiving circuits are somewhat more complicated than where a crystal detector is used still the former does not have to be constantly adjusted as does the latter and this is another very great advantage4 ,taken all in all the vacuum tube detector is the most sensitive and the most satisfactory of the detectors that are in use at the present time4 ,not only is the vacuum tube a detector of electric wave signals and speech and music but it can also be used to amplify them1 that is1 to make them stronger and1 hence1 louder in the telephone receiver and further its powers of amplification are so great that it will reproduce them by means of a loud speaker1 just as a horn amplifies the sounds of a phonograph reproducer1 until they can be heard by a room or an auditorium full of people4 ,there are two general types of loud speakers1 though both use the principle of the telephone receiver4 ,the construction of these loud speakers will be fully described in a later chapter4 ,assembled ,vacuum ,tube ,receiving ,sets4--,you can buy a receiving set with a vacuum tube detector from the very simplest type1 which is described in this chapter1 to those that are provided with regenerative circuits and amplifying tubes or both1 which we shall describe in later chapters1 from dealers in electrical apparatus generally4 ,while one of these sets costs more than you can assemble a set for yourself1 still1 especially in the beginning1 it is a good plan to buy an assembled one for it is fitted with a panel on which the adjusting knobs of the rheostat1 tuning coil and condenser are mounted and this makes it possible to operate it as soon as you get it home and without the slightest trouble on your part4 ,you can1 however1 buy all the various parts separately and mount them yourself4 ,if you want the receptor simply for receiving then it is a good scheme to have all of the parts mounted in a box or enclosed case1 but if you want it for experimental purposes then the parts should be mounted on a base or a panel so that all of the connections are in sight and accessible4 ,a ,simple ,vacuum ,tube ,receiving ,set4--,for this set you should use3 7#a7 a loose coupled tuning coil1 7#b7 a variable condenser1 7#c7 a vacuum tube detector1 7#d7 an ,a or storage battery giving #f volts1 7#e7 a ,b or dry cell battery giving #bb-a_/b volts1 7#f7 a rheostat for varying the storage battery current1 and 7#g7 a pair of #b1jjj-ohm head telephone receivers4 ,the loose coupled tuning coil1 the variable condenser and the telephone receivers are the same as those described in ,chapter ,,iii4 ,the ,vacuum ,tube ,detector4 ,with ,two ,electrodes4--,a vacuum tube in its simplest form consists of a glass bulb like an incandescent lamp in which a wire filament and a metal plate are sealed as shown in ,fig4 #cg1 ,the air is then pumped out of the tube and a vacuum left or after it is exhausted it is filled with nitrogen1 which cannot burn4 ,illustration3 ,fig4 #cg4--,two ,electrode ,vacuum ,tube ,detectors4 ,when the vacuum tube is used as a detector1 the wire filament is heated red-hot and the metal plate is charged with positive electricity though it remains cold4 ,the wire filament is formed into a loop like that of an incandescent lamp and its outside ends are connected with a #f-volt storage battery1 which is called the ,a battery2 then the or positive terminal of a #bb-a_/b volt dry cell battery1 called the ,b battery1 is connected to the metal plate while the - or negative terminal of the battery is connected to one of the terminals of the wire filament4 ,the diagram1 ,fig4 #cg1 simply shows how the two electrode vacuum tube1 the ,a or dry battery1 and the ,b or storage battery are connected up4 ,three ,electrode ,vacuum ,tube ,detector4--,the three electrode vacuum tube detector shown at ,a in ,fig4 #ch1 is much more sensitive than the two electrode tube and has1 in consequence1 all but supplanted it4 ,in this more recent type of vacuum tube the third electrode1 or grid1 as it is called1 is placed between the wire filament and the metal plate and this allows the current to be increased or decreased at will to a very considerable extent4 ,illustration3 ,fig4 #ch4--,three ,electrode ,vacuum ,tube ,detector and ,battery ,connections4 ,the way the three electrode vacuum tube detector is connected with the batteries is shown at ,b4 ,the plate1 the ,a or dry cell battery and one terminal of the filament are connected in series--that is1 one after the other1 and the ends of the filament are connected to the ,b or storage battery4 ,in assembling a receiving set you must1 of course1 have a socket for the vacuum tube4 ,a vacuum tube detector costs from #e4jj to #f4jj4 ,the ,dry ,cell and ,storage ,batteries4--,the reason that a storage battery is used for heating the filament of the vacuum tube detector is because the current delivered is constant1 whereas when a dry cell battery is used the current soon falls off and1 hence1 the heat of the filament gradually grows less4 ,the smallest ,a or #f volt storage battery on the market has a capacity of #bj to #dj ampere hours1 weighs #ac pounds and costs about #aj4jj4 ,it is shown at ,a in ,fig4 #ci4 ,the ,b or dry cell battery for the vacuum tube plate circuit that gives #bb-a_/b volts can be bought already assembled in sealed boxes4 ,the small size is fitted with a pair of terminals while the larger size is provided with taps so that the voltage required by the plate can be adjusted as the proper operation of the tube requires careful regulation of the plate voltage4 ,a dry cell battery for a plate circuit is shown at ,b4 ,illustration3 ,fig4 #ci4--;,a and ,b ,batteries for ,vacuum ,tube ,detectors4 ,the ,filament ,rheostat4--,an adjustable resistance1 called a rheostat1 must be used in the filament and storage battery circuit so that the current flowing through the filament can be controlled to a nicety4 ,the rheostat consists of an insulating and a heat resisting form on which is wound a number of turns of resistance wire4 ,a movable contact arm that slides over and presses on the turns of wire is fixed to the knob on top of the rheostat4 ,a rheostat that has a resistance of #f ohms and a current carrying capacity of #a4e amperes which can be mounted on a panel board is the right kind to use4 ,it is shown at ,a and ,b in ,fig4 #dj and costs #a4be4 ,illustration3 ,fig4 #dj4--,rheostat for the ,a or ,storage ,battery ,current4 ,assembling the ,parts4--,begin by placing all of the separate parts of the receiving set on a board or a base of other material and set the tuning coil on the left hand side with the adjustable switch end toward the right hand side so that you can reach it easily4 ,then set the variable condenser in front of it1 set the vacuum tube detector at the right hand end of the tuning coil and the rheostat in front of the detector4 ,place the two sets of batteries back of the instruments and screw a couple of binding posts a and b to the right hand lower edge of the base for connecting in the head phones all of which is shown at ,a in ,fig4 #da4 ,illustration3 7,a7 ,fig4 #da4--,top ,view of ,apparatus ,layout for a ,vacuum ,tube ,detector ,receiving ,set4 ,illustration3 7,b7 ,fig4 #da4--,wiring ,diagram of a ,simple ,vacuum ,tube ,receiving ,set4 ,connecting ,up the ,parts4--,to wire up the different parts begin by connecting the sliding contact of the primary coil of the loose coupled tuning coil 7this you will remember is the outside one that is wound with fine wire7 to the upper post of the lightning switch and connect one terminal of this coil with the water pipe4 ,now connect the free end of the secondary coil of the tuning coil 7this is the inside coil that is wound with heavy wire7 to one of the binding posts of the variable condenser and connect the movable contact arm of the adjustable switch of the primary of the tuning coil with the other post of the variable condenser4 ,next connect the grid of the vacuum tube to one of the posts of the condenser and then connect the plate of the tube to the carbon terminal of the ,b or dry cell battery which is the or positive pole and connect the zinc terminal of the - or negative pole to the binding post a1 connect the post b to the other side of the variable condenser and then connect the terminals of the head phones to the binding posts a and b4 ,whatever you do be careful not to get the plate connections of the battery reversed4 ,now connect one of the posts of the rheostat to one terminal of the filament and the other terminal of the filament to the - or negative terminal of the ,a or storage battery and the or positive terminal of the ,a or storage battery to the other post of the rheostat4 ,finally connect the or positive terminal of the ,a or storage battery with the wire that runs from the head phones to the variable condenser1 all of which is shown in the wiring diagram at ,b in ,fig4 #da4 ,adjusting the ,vacuum ,tube ,detector ,receiving ,set4--,a vacuum tube detector is tuned exactly in the same way as the ,crystal ,detector ,set ,no4 #b described in ,chapter ,,iii1 in-so-far as the tuning coil and variable condenser are concerned4 ,the sensitivity of the vacuum tube detector receiving set and1 hence1 the distance over which signals and other sounds can be heard depends very largely on the sensitivity of the vacuum tube itself and this in turn depends on3 7#a7 the right amount of heat developed by the filament1 or filament brilliancy as it is called1 7#b7 the right amount of voltage applied to the plate1 and 7#c7 the extent to which the tube is exhausted where this kind of a tube is used4 ,to vary the current flowing from the ,a or storage battery through the filament so that it will be heated to the right degree you adjust the rheostat while you are listening in to the signals or other sounds4 ,by carefully adjusting the rheostat you can easily find the point at which it makes the tube the most sensitive4 ,a rheostat is also useful in that it keeps the filament from burning out when the current from the battery first flows through it4 ,you can very often increase the sensitiveness of a vacuum tube after you have used it for a while by recharging the ,a or storage battery4 ,the degree to which a vacuum tube has been exhausted has a very pronounced effect on its sensitivity4 ,the longer the tube is used the lower its vacuum gets and generally the less sensitive it becomes4 ,when this takes place 7and you can only guess at it7 you can very often make it more sensitive by warming it over the flame of a candle4 ,vacuum tubes having a gas content 7in which case they are1 of course1 no longer vacuum tubes in the strict sense7 make better detectors than tubes from which the air has been exhausted and which are sealed off in this evacuated condition because their sensitiveness is not dependent on the degree of vacuum as in the latter tubes4 ,moreover1 a tube that is completely exhausted costs more than one that is filled with gas4 ,,chapter ,,ix ,,vacuum ,,tube ,,amplifier ,,receiving ,,sets ,the reason a vacuum tube detector is more sensitive than a crystal detector is because while the latter merely rectifies the oscillating current that surges in the receiving circuits1 the former acts as an amplifier at the same time4 ,the vacuum tube can be used as a separate amplifier in connection with either3 7#a7 a crystal detector or 7#b7 a vacuum tube detector1 and 7a7 it will amplify either the radio frequency currents1 that is the high frequency oscillating currents which are set up in the oscillation circuits or 7b7 it will amplify the audio frequency currents1 that is1 the low frequency alternating currents that flow through the head phone circuit4 ,to use the amplified radio frequency oscillating currents or amplified audio frequency alternating currents that are set up by an amplifier tube either a high resistance1 called a grid leak1 or an amplifying transformer1 with or without an iron core1 must be connected with the plate circuit of the first amplifier tube and the grid circuit of the next amplifier tube or detector tube1 or with the wire point of a crystal detector4 ,where two or more amplifier tubes are coupled together in this way the scheme is known as cascade amplification4 ,where either a radio frequency transformer1 that is one without the iron core1 or an audio frequency transformer1 that is one with the iron core1 is used to couple the amplifier tube circuits together better results are obtained than where a high resistance grid leak is used1 but the amplifying tubes have to be more carefully shielded from each other or they will react and set up a howling noise in the head phones4 ,on the other hand grid leaks cost less but they are more troublesome to use as you have to find out for yourself the exact resistance value they must have and this you can do only by testing them out4 ,a ,grid ,leak ,amplifier ,receiving ,set4 ,with ,crystal ,detector4--,the apparatus you need for this set includes3 7#a7 a loose coupled tuning coil1 7#b7 a variable condenser1 7#c7 two fixed condensers1 7#d7 a crystal detector1 or better a vacuum tube detector1 7#e7 an ,a or #f volt storage battery1 7#f7 a rheostat1 7#g7 a ,b or #bb-a_/b volt dry cell battery1 7#h7 a fixed resistance unit1 or leak grid as it is called1 and 7#i7 a pair of head-phones4 ,the tuning coil1 variable condenser1 fixed condensers1 crystal detectors and head-phones are exactly the same as those described in ,set ,no4 #b in ,chapter ,,iii4 ,the ,a and ,b batteries are exactly the same as those described in ,chapter ,,viii4 ,the vacuum tube amplifier and the grid leak are the only new pieces of apparatus you need and not described before4 ,the ,vacuum ,tube ,amplifier4--,this consists of a three electrode vacuum tube exactly like the vacuum tube detector described in ,chapter ,,viii and pictured in ,fig4 #ch1 except that instead of being filled with a non-combustible gas it is evacuated1 that is1 the air has been completely pumped out of it4 ,the gas filled tube1 however1 can be used as an amplifier and either kind of tube can be used for either radio frequency or audio frequency amplification1 though with the exhausted tube it is easier to obtain the right plate and filament voltages for good working4 ,the ,fixed ,resistance ,unit1 or ,grid ,leak4--,grid leaks are made in different ways but all of them have an enormously high resistance4 ,one way of making them consists of depositing a thin film of gold on a sheet of mica and placing another sheet of mica on top to protect it the whole being enclosed in a glass tube as shown at ,a in ,fig4 #db4 ,these grid leaks are made in units of from #ej1jjj ohms 74#je megohm7 to #e1jjj1jjj ohms 7#e megohms7 and cost from #a to #b4 ,illustration3 ,fig4 #db4--;,grid ,leaks and ,how to ,connect ,them up4 ,as the value of the grid leak you will need depends very largely upon the construction of the different parts of your receiving set and on the kind of aerial wire system you use with it you will have to try out various resistances until you hit the right one4 ,the resistance that will give the best results1 however1 lies somewhere between #ejj1jjj ohms 7#a_/b a megohm7 and #c1jjj1jjj ohms 7#c megohms7 and the only way for you to find this out is to buy #a_/b1 #a and #b megohm grid leak resistances and connect them up in different ways1 as shown at ,b1 until you find the right value4 ,assembling the ,parts for a ,crystal ,detector ,set4--,begin by laying the various parts out on a base or a panel with the loose coupled tuning coil on the left hand side1 but with the adjustable switch of the secondary coil on the right hand end or in front according to the way it is made4 ,then place the variable condenser1 the rheostat1 the crystal detector and the binding posts for the head phones in front of and in a line with each other4 ,set the vacuum tube amplifier back of the rheostat and the ,a and ,b batteries back of the parts or in any other place that may be convenient4 ,the fixed condensers and the grid leak can be placed anywhere so that it will be easy to connect them in and you are ready to wire up the set4 ,connecting ,up the ,parts for a ,crystal ,detector4--,first connect the sliding contact of the primary of the tuning coil to the leading-in wire and one of the end wires of the primary to the water pipe1 as shown in ,fig4 #dc4 ,now connect the adjustable arm that makes contact with one end of the secondary of the tuning coil to one of the posts of the variable condenser2 then connect the other post of the latter with a post of the fixed condenser and the other post of this with the grid of the amplifying tube4 ,illustration3 ,fig4 #dc4--;,crystal ,detector ,receiving ,set with ,vacuum ,tube ,amplifier 7,resistance ,coupled74 ,connect the first post of the variable condenser to the or positive electrode of the ,a battery and its - or negative electrode with the rotating contact arm of the rheostat4 ,next connect one end of the resistance coil of the rheostat to one of the posts of the amplifier tube that leads to the filament and the other filament post to the or positive electrode of the ,a battery4 ,this done connect the negative1 that is1 the zinc pole of the ,b battery to the positive electrode of the ,a battery and connect the positive1 or carbon pole of the former with one end of the grid leak and connect the other end of this to the plate of the amplifier tube4 ,to the end of the grid leak connected with the plate of the amplifier tube connect the metal point of your crystal detector1 the crystal of the latter with one post of the head phones and the other post of them with the other end of the grid leak and1 finally1 connect a fixed condenser in parallel with--that is across the ends of the grid leak1 all of which is shown in the wiring diagram in ,fig4 #dc4 ,a ,grid ,leak ,amplifying ,receiving ,set ,with ,vacuum ,tube ,detector4--,a better amplifying receiving set can be made than the one just described by using a vacuum tube detector instead of the crystal detector4 ,this set is built up exactly like the crystal detector described above and shown in ,fig4 #dc up to and including the grid leak resistance1 but shunted across the latter is a vacuum tube detector1 which is made and wired up precisely like the one shown at ,a in ,fig4 #da in the chapter ahead of this one4 ,the way a grid leak and vacuum tube detector with a one-step amplifier are connected up is shown at ,a in ,fig4 #dd4 ,where you have a vacuum tube detector and one or more amplifying tubes connected up1 or in cascade as it is called1 you can use an ,a1 or storage battery of #f volts for all of them as shown at ,b in ,fig4 #dd1 but for every vacuum tube you use you must have a ,b or #bb-a_/b volt dry battery to charge the plate with4 ,illustration3 7,a7 ,fig4 #dd--,vacuum ,tube ,detector ,set with ,one ,step ,amplifier 7,resistance ,coupled74 ,illustration3 7,b7 ,fig4 #dd4--,wiring ,diagram for ,using ,one ,a or ,storage ,battery with an ,amplifier and a ,detector ,tube4 ,a ,radio ,frequency ,transformer ,amplifying ,receiving ,set4--,instead of using a grid leak resistance to couple up the amplifier and detector tube circuits you can use a radio frequency transformer1 that is1 a transformer made like a loose coupled tuning coil1 and without an iron core1 as shown in the wiring diagram at ,a in ,fig4 #de4 ,in this set1 which gives better results than where a grid leak is used1 the amplifier tube is placed in the first oscillation circuit and the detector tube in the second circuit4 ,illustration3 7,a7 ,fig4 #de4--,wiring ,diagram for a ,radio ,frequency ,transformer ,amplifying ,receiving ,set4 ,illustration3 7,b7 ,fig4 #de4--,radio ,frequency ,transformer4 ,since the radio frequency transformer has no iron core the high frequency1 or radio frequency oscillating currents1 as they are called1 surge through it and are not changed into low frequency1 or audio frequency pulsating currents1 until they flow through the detector4 ,since the diagram shows only one amplifier and one radio frequency transformer1 it is consequently a one step amplifier2 however1 two1 three or more1 amplifying tubes can be connected up by means of an equal number of radio frequency transformers when you will get wonderful results4 ,where a six step amplifier1 that is1 where six amplifying tubes are connected together1 or in cascade1 the first three are usually coupled up with radio frequency transformers and the last three with audio frequency transformers4 ,a radio frequency transformer is shown at ,b and costs #f to #g4 ,an ,audio ,frequency ,transformer ,amplifying ,receiving ,set4--,where audio frequency transformers are used for stepping up the voltage of the current of the detector and amplifier tubes1 the radio frequency current does not get into the plate circuit of the detector at all for the reason that the iron core of the transformer chokes them off1 hence1 the succeeding amplifiers operate at audio frequencies4 ,an audio frequency transformer is shown at ,a in ,fig4 #df and a wiring diagram showing how the tubes are connected in cascade with the transformers is shown at ,b2 it is therefore a two-step audio frequency receiving set4 ,illustration3 7,a7 ,fig4 #df4--;,audio ,frequency ,transformer4 ,illustration3 7,b7 ,fig4 #df--,wiring ,diagram for an ,audio ,frequency ,transformer ,amplifying ,receiving ,set4 7,with ,vacuum ,tube ,detector and ,two ,step ,amplifier ,tubes47 ,a ,six ,step ,amplifier ,receiving ,set ,with a ,loop ,aerial4--,by using a receiving set having a three step radio frequency and a three step audio frequency1 that is1 a set in which there are coupled three amplifying tubes with radio frequency transformers and three amplifying tubes with audio frequency transformers as described under the caption ,a ,radio ,frequency ,transformer ,receiving ,set1 you can use a loop aerial in your room thus getting around the difficulties--if such there be--in erecting an out-door aerial4 ,you can easily make a loop aerial by winding #aj turns of ,no4 #ad or #af copper wire about #a_/af inch apart on a wooden frame two feet on the side as shown in ,fig4 #dg4 ,with this six step amplifier set and loop aerial you can receive wave lengths of #aej to #fjj meters from various high power stations which are at considerable distances away4 ,illustration3 7,a7 ,fig4 #dg4--,six ,step ,amplifier with ,loop ,aerial4 ,illustration3 7,b7 ,fig4 #dg4--;,efficient ,regenerative ,receiving ,set4 7,with ,three ,coil ,loose ,coupler ,tuner47 ,how to ,prevent ,howling4--,where radio frequency or audio frequency amplifiers are used to couple your amplifier tubes in cascade you must take particular pains to shield them from one another in order to prevent the feed back of the currents through them1 which makes the head phones or loud speaker howl4 ,to shield them from each other the tubes should be enclosed in metal boxes and placed at least #f inches apart while the transformers should be set so that their cores are at right angles to each other and these also should be not less than six inches apart4 ,,chapter ,x ,,regenerative ,,amplification ,,receiving ,,sets ,while a vacuum tube detector has an amplifying action of its own1 and this accounts for its great sensitiveness1 its amplifying action can be further increased to an enormous extent by making the radio frequency currents that are set up in the oscillation circuits react on the detector4 ,such currents are called feed-back or regenerative currents and when circuits are so arranged as to cause the currents to flow back through the detector tube the amplification keeps on increasing until the capacity of the tube itself is reached4 ,it is like using steam over and over again in a steam turbine until there is no more energy left in it4 ,a system of circuits which will cause this regenerative action to take place is known as the ,armstrong circuits and is so called after the young man who discovered it4 ,since the regenerative action of the radio frequency currents is produced by the detector tube itself and which sets up an amplifying effect without the addition of an amplifying tube1 this type of receiving set has found great favor with amateurs1 while in combination with amplifying tubes it multiplies their power proportionately and it is in consequence used in one form or another in all the better sets4 ,there are many different kinds of circuits which can be used to produce the regenerative amplification effect while the various kinds of tuning coils will serve for coupling them2 for instance a two or three slide single tuning coil will answer the purpose but as it does not give good results it is not advisable to spend either time or money on it4 ,a better scheme is to use a loose coupler formed of two or three honeycomb or other compact coils1 while a variocoupler or a variometer or two will produce the maximum regenerative action4 ,the ,simplest ,type of ,regenerative ,receiving ,set4 ,with ,loose ,coupled ,tuning ,coil4--,while this regenerative set is the simplest that will give anything like fair results it is here described not on account of its desirability1 but because it will serve to give you the fundamental idea of how the feed-back circuit is formed4 ,for this set you need3 7#a7 a loose-coupled tuning coil such as described in ,chapter ,,iii1 7#b7 a variable condenser of 4#jja mfd4 7microfarad7 capacitance2 7#c7 one fixed condenser of 4#jja mfd42 7#d7 one fixed condenser for the grid leak circuit of 4#jjjbe mfd42 7#e7 a grid leak of #a_/b to #b megohms resistance2 7#f7 a vacuum tube detector2 7#g7 an ,a #f volt battery2 7#h7 a rheostat2 7#i7 a ,b #bb #a_/b volt battery2 and 7#aj7 a pair of #bjjj ohm head phones4 ,connecting ,up the ,parts4--,begin by connecting the leading-in wire of the aerial with the binding post end of the primary coil of the loose coupler as shown in the wiring diagram ,fig4 #dh and then connect the sliding contact with the water pipe or other ground4 ,connect the binding post end of the primary coil with one post of the variable condenser1 connect the other post of this with one of the posts of the 4#jjjbe mfd4 condenser and the other end of this with the grid of the detector tube2 then around this condenser shunt the grid leak resistance4 ,illustration3 ,fig4 #dh4--,simple ,regenerative ,receiving ,set4 7,with ,loose ,coupler ,tuner47 ,next connect the sliding contact of the primary coil with the other post of the variable condenser and from this lead a wire on over to one of the terminals of the filament of the vacuum tube2 to the other terminal of the filament connect one of the posts of the rheostat and connect the other post to the - or negative electrode of the ,a battery and then connect the or positive electrode of it to the other terminal of the filament4 ,connect the or positive electrode of the ,a battery with one post of the 4#jja mfd4 fixed condenser and connect the other post of this to one of the ends of the secondary coil of the tuning coil and which is now known as the tickler coil2 then connect the other end of the secondary1 or tickler coil to the plate of the vacuum tube4 ,in the wiring diagram the secondary1 or tickler coil is shown above and in a line with the primary coil but this is only for the sake of making the connections clear2 in reality the secondary1 or tickler coil slides to and fro in the primary coil as shown and described in ,chapter ,,iii4 ,finally connect the negative1 or zinc pole of the ,b battery to one side of the fixed condenser1 the positive1 or carbon1 pole to one of the terminals of the head phones and the other terminal of this to the other post of the fixed condenser when your regenerative set is complete4 ,an ,efficient ,regenerative ,receiving ,set4 ,with ,three ,coil ,loose ,coupler4--,to construct a really good regenerative set you must use a loose coupled tuner that has three coils1 namely a primary1 a secondary and a tickler coil4 ,a tuner of this kind is made like an ordinary loose coupled tuning coil but it has a third coil as shown at ,a and ,b in ,fig4 #di4 ,the middle coil1 which is the secondary1 is fixed to the base1 and the large outside coil1 which is the primary1 is movable1 that is it slides to and fro over the middle coil1 while the small inside coil1 which is the tickler1 is also movable and can slide in or out of the middle coil4 ,none of these coils is variable2 all are wound to receive waves up to #cfj meters in length when used with a variable condenser of 4#jja mfd4 capacitance4 ,in other words you slide the coils in and out to get the right amount of coupling and you tune by adjusting the variable condenser to get the exact wave length you want4 ,illustration3 7,a7 ,fig4 #di4--;,diagram of a ,three ,coil ,coupler4 ,illustration3 7,b7 ,fig4 #di4--,three ,coil ,loose ,coupler ,tuner4 ,with ,compact ,coils4--,compact coil tuners are formed of three fixed inductances wound in flat coils1 and these are pivoted in a mounting so that the distance between them and1 therefore1 the coupling1 can be varied1 as shown at ,a in ,fig4 #ej4 ,these coils are wound up by the makers for various wave lengths ranging from a small one that will receive waves of any length up to #cfj meters to a large one that has a maximum of #bd1jjj meters4 ,for an amateur set get three of the smallest coils when you can not only hear amateur stations that send on a #bjj meter wave but broadcasting stations that send on a #cfj meter wave4 ,illustration3 ,fig4 #ej4--;,honeycomb ,inductance ,coil4 ,these three coils are mounted with panel plugs which latter fit into a stand1 or mounting1 so that the middle coil is fixed1 that is1 stationary1 while the two outside coils can be swung to and fro like a door2 this scheme permits small variations of coupling to be had between the coils and this can be done either by handles or by means of knobs on a panel board4 ,while ,i have suggested the use of the smallest size coils1 you can get and use those wound for any wave length you want to receive and when those are connected with variometers and variable condensers1 and with a proper aerial1 you will have a highly efficient receptor that will work over all ranges of wave lengths4 ,the smallest size coils cost about #a4ej apiece and the mounting costs about #f or #g each4 ,the ,a ,battery ,potentiometer4--,this device is simply a resistance like the rheostat described in connection with the preceding vacuum tube receiving sets but it is wound to #bjj or #cjj ohms resistance as against #a-a_/b to #f ohms of the rheostat4 ,it is1 however1 used as well as the rheostat4 ,with a vacuum tube detector1 and especially with one having a gas-content1 a potentiometer is very necessary as it is only by means of it that the potential of the plate of the detector can be accurately regulated4 ,the result of proper regulation is that when the critical potential value is reached there is a marked increase in the loudness of the sounds that are emitted by the head phones4 ,as you will see from ,a in ,fig4 #ea it has three taps4 ,the two taps which are connected with the ends of the resistance coil are shunted around the ,a battery and the third tap1 which is attached to the movable contact arm1 is connected with the ,b battery tap1 see ,b1 at which this battery gives #ah volts4 ,since the ,a battery gives #f volts you can vary the potential of the plate from #ah to #bd volts4 ,the potentiometer must never be shunted around the ,b battery or the latter will soon run down4 ,a potentiometer costs a couple of dollars4 ,illustration3 7,a7 ,fig4 #ea4--,the ,use of the ,potentiometer4 ,the ,parts and ,how to ,connect ,them ,up4--,for this regenerative set you will need3 7#a7 a honeycomb or other compact three-coil tuner1 7#b7 two variable 74#jja and 4#jjje mfd47 condensers2 7#c7 a 4#jjjbe mfd4 fixed condenser2 7#d7 a #a_/b to #b megohm grid leak2 7#e7 a tube detector2 7#f7 a #f volt ,a battery2 7#g7 a rheostat2 7#h7 a potentiometer2 7#i7 an #ah or #bj volt ,b battery2 7#aj7 a fixed condenser of 4#jja mfd4 fixed condenser2 and 7#aa7 a pair of #bjjj ohm head phones4 ,to wire up the parts connect the leading-in wire of the aerial with the primary coil1 which is the middle one of the tuner1 and connect the other terminal with the ground4 ,connect the ends of the secondary coil1 which is the middle one1 with the posts of the variable condenser and connect one of the posts of the latter with one post of the fixed 4#jjjbe mfd4 condenser and the other post of this with the grid2 then shunt the grid leak around it4 ,next connect the other post of the variable condenser to the - or negative electrode of the ,a battery2 the or positive electrode of this to one terminal of the detector filament and the other end of the latter to the electrode of the ,a battery4 ,now connect one end of the tickler coil with the detector plate and the other post to the fixed 4#jja mfd4 condenser1 then the other end of this to the positive or carbon pole of the ,b battery4 ,this done shunt the potentiometer around the ,a battery and run a wire from the movable contact of it 7the potentiometer7 over to the #ah volt tap1 7see ,b1 ,fig4 #ea71 of the ,b battery4 ,finally1 shunt the head phones and the 4#jja mfd4 fixed condenser and you are ready to try out conclusions4 ,a ,regenerative ,audio ,frequency ,amplifier ,receiving ,set4--,the use of amateur regenerative cascade audio frequency receiving sets is getting to be quite common4 ,to get the greatest amplification possible with amplifying tubes you have to keep a negative potential on the grids4 ,you can1 however1 get very good results without any special charging arrangement by simply connecting one post of the rheostat with the negative terminal of the filament and connecting the low potential end of the secondary of the tuning coil with the - or negative electrode of the ,a battery4 ,this scheme will give the grids a negative bias of about #a volt4 ,you do not need to bother about these added factors that make for high efficiency until after you have got your receiving set in working order and understand all about it4 ,the ,parts and ,how to ,connect ,them ,up4--,exactly the same parts are needed for this set as the one described above1 but in addition you will want3 7#a7 two more rheostats2 7#b7 two more sets of ,b #bb-a_/b volt batteries2 7#c7 two amplifier tubes1 and 7#d7 two audio frequency transformers as described in ,chapter ,,ix and pictured at ,a in ,fig4 #df4 ,to wire up the parts begin by connecting the leading-in wire to one end of the primary of the tuning coil and then connect the other end of the coil with the ground4 ,a variable condenser of 4#jja mfd4 capacitance can be connected in the ground wire1 as shown in ,fig4 #eb1 to good advantage although it is not absolutely needed4 ,now connect one end of the secondary coil to one post of a 4#jja mfd4 variable condenser and the other end of the secondary to the other post of the condenser4 ,illustration3 ,fig4 #eb4--,regenerative ,audio ,frequency ,amplifier ,receiving ,set4 ,next bring a lead 7wire7 from the first post of the variable condenser over to the post of the first fixed condenser and connect the other post of the latter with the grid of the detector tube4 ,shunt #a_/b to #b megohm grid leak resistance around the fixed condenser and then connect the second post of the variable condenser to one terminal of the detector tube filament4 ,run this wire on over and connect it with the first post of the second rheostat1 the second post of which is connected with one terminal of the filament of the first amplifying tube2 then connect the first post of the rheostat with one end of the secondary coil of the first audio frequency transformer1 and the other end of this coil with the grid of the first amplifier tube4 ,connect the lead that runs from the second post of variable condenser to the first post of the third rheostat1 the second post of which is connected with one terminal of the second amplifying tube2 then connect the first post of the rheostat with one end of the secondary coil of the second audio frequency transformer and the other end of this coil with the grid of the second amplifier tube4 ,this done connect the - or negative electrode of the ,a battery with the second post of the variable condenser and connect the or positive electrode with the free post of the first rheostat1 the other post of which connects with the free terminal of the filament of the detector4 ,from this lead tap off a wire and connect it to the free terminal of the filament of the first amplifier tube1 and finally connect the end of the lead with the free terminal of the filament of the second amplifier tube4 ,next shunt a potentiometer around the ,a battery and connect the third post1 which connects with the sliding contact1 to the negative or zinc pole of a ,b battery1 then connect the positive or carbon pole of it to the negative or zinc pole of a second ,b battery and the positive or carbon pole of the latter with one end of the primary coil of the second audio frequency transformer and the other end of it to the plate of the first amplifying tube4 ,run the lead on over and connect it to one of the terminals of the second fixed condenser and the other terminal of this with the plate of the second amplifying tube4 ,then shunt the headphones around the condenser4 ,finally connect one end of the tickler coil of the tuner with the plate of the detector tube and connect the other end of the tickler to one end of the primary coil of the first audio frequency transformer and the other end of it to the wire that connects the two ,b batteries together4 ,,chapter ,,xi ,,short ,,wave ,,regenerative ,,receiving ,,sets ,a short wave receiving set is one that will receive a range of wave lengths of from #aej to #fjj meters while the distance over which the waves can be received as well as the intensity of the sounds reproduced by the headphones depends on3 7#a7 whether it is a regenerative set and 7#b7 whether it is provided with amplifying tubes4 ,high-grade regenerative sets designed especially for receiving amateur sending stations that must use a short wave length are built on the regenerative principle just like those described in the last chapter and further amplification can be had by the use of amplifier tubes as explained in ,chapter ,,ix1 but the new feature of these sets is the use of the variocoupler and one or more variometers4 ,these tuning devices can be connected up in different ways and are very popular with amateurs at the present time4 ,differing from the ordinary loose coupler the variometer has no movable contacts while the variometer is provided with taps so that you can connect it up for the wave length you want to receive4 ,all you have to do is to tune the oscillation circuits to each other is to turn the rotor1 which is the secondary coil1 around in the stator1 as the primary coil is called in order to get a very fine variation of the wave length4 ,it is this construction that makes sharp tuning with these sets possible1 by which is meant that all wave lengths are tuned out except the one which the receiving set is tuned for4 ,a ,short ,wave ,regenerative ,receiver--,with ,one ,variometer and ,three ,variable ,condensers4--,this set also includes a variocoupler and a grid coil4 ,the way that the parts are connected together makes it a simple and at the same time a very efficient regenerative receiver for short waves4 ,while this set can be used without shielding the parts from each other the best results are had when shields are used4 ,the parts you need for this set include3 7#a7 one variocoupler2 7#b7 one 4#jja microfarad variable condenser2 7#c7 one 4#jjje microfarad variable condenser2 7#d7 one 4#jjjg microfarad variable condenser2 7#e7 one #b megohm grid leak2 7#f7 one vacuum tube detector2 7#g7 one #f volt ,a battery2 7#h7 one #f ohm1 #a-a_/b ampere rheostat2 7#i7 one #bjj ohm potentiometer2 7#aj7 one #bb-a_/b volt ,b battery2 7#aa7 one 4#jja microfarad fixed condenser1 7#ab7 one pair of #b1jjj ohm headphones1 and 7#ac7 a variometer4 ,the ,variocoupler4--,a variocoupler consists of a primary coil wound on the outside of a tube of insulating material and to certain turns of this taps are connected so that you can fix the wave length which your aerial system is to receive from the shortest wave2 i4e41 #aej meters on up by steps to the longest wave1 i4e41 #fjj meters1 which is the range of most amateur variocouplers that are sold in the open market4 ,this is the part of the variocoupler that is called the stator4 ,the secondary coil is wound on the section of a ball mounted on a shaft and this is swung in bearings on the stator so that it can turn in it4 ,this part of the variocoupler is called the rotor and is arranged so that it can be mounted on a panel and adjusted by means of a knob or a dial4 ,a diagram of a variocoupler is shown at ,a in ,fig4 #ec1 and the coupler itself at ,b4 ,there are various makes and modifications of variocouplers on the market but all of them are about the same price which is #f4jj or #h4jj4 ,illustration3 ,fig4 #ec4--;,how the ,variocoupler is ,made and ,works4 ,the ,variometer4--,this device is quite like the variocoupler1 but with these differences3 7#a7 the rotor turns in the stator1 which is also the section of a ball1 and 7#b7 one end of the primary is connected with one end of the secondary coil4 ,to be really efficient a variometer must have a small resistance and a large inductance as well as a small dielectric loss4 ,to secure the first two of these factors the wire should be formed of a number of fine1 pure copper wires each of which is insulated and the whole strand then covered with silk4 ,this kind of wire is the best that has yet been devised for the purpose and is sold under the trade name of litzendraht4 ,a new type of variometer has what is known as a basket weave1 or wavy wound stator and rotor4 ,there is no wood1 insulating compound or other dielectric materials in large enough quantities to absorb the weak currents that flow between them1 hence weaker sounds can be heard when this kind of a variometer is used4 ,with it you can tune sharply to waves under #bjj meters in length and up to and including wave lengths of #cfj meters4 ,when amateur stations of small power are sending on these short waves this style of variometer keeps the electric oscillations at their greatest strength and1 hence1 the reproduced sounds will be of maximum intensity4 ,a wiring diagram of a variometer is shown at ,a in ,fig4 #ed and a basketball variometer is shown complete at ,b4 ,illustration3 ,fig4 #ed4--;,how the ,variometer is ,made and ,works4 ,connecting ,up the ,parts4--,to hook-up the set connect the leading-in wire to one end of the primary coil1 or stator1 of the variocoupler and solder a wire to one of the taps that gives the longest wave length you want to receive4 ,connect the other end of this wire with one post of a 4#jja microfarad variable condenser and connect the other post with the ground as shown in ,fig4 #ee4 ,now connect one end of the secondary coil1 or rotor1 to one post of a 4#jjjg mfd4 variable condenser1 the other post of this to one end of the grid coil and the other end of this with the remaining end of the rotor of the variocoupler4 ,illustration3 ,fig4 #ee4--,short ,wave ,regenerative ,receiving ,set 7one ,variometer and three ,variable ,condensers47 ,next connect one post of the 4#jjjg mfd4 condenser with one of the terminals of the detector filament2 then connect the other post of this condenser with one post of the 4#jjje mfd4 variable condenser and the other post of this with the grid of the detector1 then shunt the megohm grid leak around the latter condenser4 ,this done connect the other terminal of the filament to one post of the rheostat1 the other post of this to the - or negative electrode of the #f volt ,a battery and the or positive electrode of the latter to the other terminal of the filament4 ,shunt the potentiometer around the ,a battery and connect the sliding contact with the - or zinc pole of the ,b battery and the or carbon pole with one terminal of the headphone2 connect the other terminal to one of the posts of the variometer and the other post of the variometer to the plate of the detector4 ,finally shunt a 4#jja mfd4 fixed condenser around the headphones4 ,if you want to amplify the current with a vacuum tube amplifier connect in the terminals of the amplifier circuit shown at ,a in ,figs4 #dd or #de at the point where they are connected with the secondary coil of the loose coupled tuning coil1 in those diagrams with the binding posts of ,fig4 #ee where the phones are usually connected in4 ,short ,wave ,regenerative ,receiver4 ,with ,two ,variometers and ,two ,variable ,condensers4--,this type of regenerative receptor is very popular with amateurs who are using high-grade short-wave sets4 ,when you connect up this receptor you must keep the various parts well separated4 ,screw the variocoupler to the middle of the base board or panel1 and secure the variometers on either side of it so that the distance between them will be #i or #aj inches4 ,by so placing them the coupling will be the same on both sides and besides you can shield them from each other easier4 ,for the shield use a sheet of copper on the back of the panel and place a sheet of copper between the parts1 or better1 enclose the variometers and detector and amplifying tubes if you use the latter in sheet copper boxes4 ,when you set up the variometers place them so that their stators are at right angles to each other for otherwise the magnetic lines of force set up by the coils of each one will be mutually inductive and this will make the headphones or loud speaker howl4 ,whatever tendency the receptor has to howl with this arrangement can be overcome by putting in a grid leak of the right resistance and adjusting the condenser4 ,the ,parts and ,how to ,connect ,them ,up4--,for this set you require3 7#a7 one variocoupler2 7#b7 two variometers2 7#c7 one 4#jja microfarad variable condenser2 7#d7 one 4#jjje microfarad variable condenser2 7#e7 one #b megohm grid leak resistance2 7#f7 one vacuum tube detector2 7#g7 one #f volt ,a battery2 7#h7 one #bjj ohm potentiometer2 7#i7 one #bb-a_/b volt ,b battery2 7#aj7 one 4#jja microfarad fixed condenser1 and 7#aa7 one pair of #b1jjj ohm headphones4 ,to wire up the set begin by connecting the leading-in wire to the fixed end of the primary coil1 or stator1 of the variocoupler1 as shown in ,fig4 #ef1 and connect one post of the 4#jja mfd4 variable condenser to the stator by soldering a short length of wire to the tap of the latter that gives the longest wave you want to receive4 ,now connect one end of the secondary coil1 or rotor1 of the variocoupler with one post of the 4#jjje mfd4 variable condenser and the other part to the grid of the detector tube4 ,connect the other end of the rotor of the variocoupler to one of the posts of the first variometer and the other post of this to one of the terminals of the detector filament4 ,illustration3 ,fig4 #ef4--,short ,wave ,regenerative ,receiving ,set 7two ,variometers and two ,variable ,condensers47 ,connect this filament terminal with the - or negative electrode of the ,a battery and the or positive electrode of this with one post of the rheostat and lead a wire from the other post to the free terminal of the filament4 ,this done shunt the potential around the ,a battery and connect the sliding contact to the - or zinc pole of the ,b battery and the or carbon pole of this to one terminal of the headphones1 while the other terminal of this leads to one of the posts of the second variometer1 the other post of which is connected to the plate of the detector tube4 ,if you want to add an amplifier tube then connect it to the posts instead of the headphones as described in the foregoing set4 ,,chapter ,,xii ,,intermediate ,,and ,,long ,,wave ,,regenerative ,,receiving ,,sets ,all receiving sets that receive over a range of wave lengths of from #aej meters to #c1jjj meters are called intermediate wave sets and all sets that receive wave lengths over a range of anything more than #c1jjj meters are called long wave sets4 ,the range of intermediate wave receptors is such that they will receive amateur1 broadcasting1 ship and shore ,navy1 commercial1 ,arlington's time and all other stations using spark telegraph damped waves or arc or vacuum tube telephone continuous waves but not continuous wave telegraph signals1 unless these have been broken up into groups at the transmitting station4 ,to receive continuous wave telegraph signals requires receiving sets of special kind and these will be described in the next chapter4 ,intermediate ,wave ,receiving ,sets4--,there are two chief schemes employed to increase the range of wave lengths that a set can receive and these are by using3 7#a7 loading coils and shunt condensers1 and 7#b7 bank-wound coils and variable condensers4 ,if you have a short-wave set and plan to receive intermediate waves with it then loading coils and fixed condensers shunted around them affords you the way to do it1 but if you prefer to buy a new receptor then the better way is to get one with bank-wound coils and variable condensers2 this latter way preserves the electrical balance of the oscillation circuits better1 the electrical losses are less and the tuning easier and sharper4 ,intermediate ,wave ,set ,with ,loading ,coils4--,for this intermediate wave set you can use either of the short-wave sets described in the foregoing chapter4 ,for the loading coils use honeycomb coils1 or other good compact inductance coils1 as shown in ,chapter ,x and having a range of whatever wave length you wish to receive4 ,the following table shows the range of wave length of the various sized coils when used with a variable condenser having a 4#jja microfarad capacitance1 the approximate inductance of each coil in millihenries and prices at the present writing3 ,,table ,,of ,,characteristics ,,of ,,honeycomb ,,coils ,approximate ,wave ,length in ,meters in ,millihenries ,inductance 4#jja mfd4 ,variable ,mounted ,appx4 ,air ,condenser4 on ,plug 4#jdj #acj-- #cge #a4dj 4#jge #ahj-- #eae #a4dj 4#ae #bdj-- #gcj #a4ej 4#c #ccj-- #ajcj #a4ej 4#f #dej-- #adfj #a4ee #a4c #ffj-- #bbjj #a4fj #b4c #icj-- #bhej #a4fe #d4e #acjj-- #djjj #a4gj #f4e #aeej-- #dhjj #a4ge #aa4 #bjej-- #fcjj #a4hj #bj4 #cjjj-- #hejj #b4jj #dj4 #djjj--abjjj #b4ae #fe4 #ejjj--aejjj #b4ce #ajj4 #fbjj--aijjj #b4fj #abe4 #gjjj--bajjj #c4jj #age4 #hbjj--bdjjj #c4ej ,these and other kinds of compact coils can be bought at electrical supply houses that sell wireless goods4 ,if your aerial is not very high or long you can use loading coils1 but to get anything like efficient results with them you must have an aerial of large capacitance and the only way to get this is to put up a high and long one with two or more parallel wires spaced a goodly distance apart4 ,the ,parts and ,how to ,connect ,them ,up4--,get 7#a7 two honeycomb or other coils of the greatest wave length you want to receive1 for in order to properly balance the aerial1 or primary oscillation circuit1 and the closed1 or secondary oscillation circuit1 you have to tune them to the same wave length2 7#b7 two 4#jja mfd4 variable condensers1 though fixed condensers will do1 and 7#c7 two small single-throw double-pole knife switches mounted on porcelain bases4 ,to use the loading coils all you have to do is to connect one of them in the aerial above the primary coil of the loose coupler1 or variocoupler as shown in the wiring diagram in ,fig4 #eg1 then shunt one of the condensers around it and connect one of the switches around this2 this switch enables you to cut in or out the loading coil at will4 ,likewise connect the other loading coil in one side of the closed1 or secondary circuit between the variable 4#jjjg mfd4 condenser and the secondary coil of the loose coupler or variocoupler as shown in ,fig4 #ec4 ,the other connections are exactly the same as shown in ,figs4 #dd and #de4 ,illustration3 ,fig4 #eg4--,wiring ,diagram ,showing ,fixed ,loading ,coils for ,intermediate ,wave ,set4 ,an ,intermediate ,wave ,set ,with ,variocoupler ,inductance ,coils4--,by using the coil wound on the rotor of the variocoupler as the tickler the coupling between the detector tube circuits and the aerial wire system increases as the set is tuned for greater wave lengths4 ,this scheme makes the control of the regenerative circuit far more stable than it is where an ordinary loose coupled tuning coil is used4 ,when the variocoupler is adjusted for receiving very long waves the rotor sets at right angles to the stator and1 since when it is in this position there is no mutual induction between them1 the tickler coil serves as a loading coil for the detector plate oscillation circuit4 ,inductance coils for short wave lengths are usually wound in single layers but bank-wound coils1 as they are called are necessary to get compactness where long wave lengths are to be received4 ,by winding inductance coils with two or more layers the highest inductance values can be obtained with the least resistance4 ,a wiring diagram of a multipoint inductance coil is shown in ,fig4 #eh4 ,you can buy this intermediate wave set assembled and ready to use or get the parts and connect them up yourself4 ,illustration3 ,fig4 #eh4--,wiring ,diagram for ,intermediate ,wave ,receptor with one ,variocoupler and #ab section ,bank-wound ,inductance ,coil4 ,the ,parts and ,how to ,connect ,them ,up4--,for this regenerative intermediate wave set get3 7#a7 one #ab section triple bank-wound inductance coil1 7#b7 one variometer1 and 7#c7 all the other parts shown in the diagram ,fig4 #eh except the variocoupler4 ,first connect the free end of the condenser in the aerial to one of the terminals of the stator of the variocoupler2 then connect the other terminal of the stator with one of the ends of the bank-wound inductance coil and connect the movable contact of this with the ground4 ,next connect a wire to the aerial between the variable condenser and the stator and connect this to one post of a 4#jjje microfarad fixed condenser1 then connect the other post of this with the grid of the detector and shunt a #b megohm grid leak around it4 ,connect a wire to the ground wire between the bank-wound inductance coil and the ground proper1 i4e41 the radiator or water pipe1 connect the other end of this to the electrode of the ,a battery and connect this end also to one of the terminals of the filament4 ,this done connect the other terminal of the filament to one post of the rheostat and the other post of this to the - or negative side of the ,a battery4 ,to the electrode of the ,a battery connect the - or zinc pole of the ,b battery and connect the or carbon pole of the latter with one post of the fixed 4#jja microfarad condenser4 ,this done connect one terminal of the tickler coil which is on the rotor of the variometer to the plate of the detector and the other terminal of the tickler to the other post of the 4#jja condenser and around this shunt your headphones4 ,or if you want to use one or more amplifying tubes connect the circuit of the first one1 see ,fig4 #de1 to the posts on either side of the fixed condenser instead of the headphones4 ,a ,long ,wave ,receiving ,set4--,the vivid imagination of ,jules ,verne never conceived anything so fascinating as the reception of messages without wires sent out by stations half way round the world2 and in these days of high power cableless stations on the five continents you can listen-in to the messages and hear what is being sent out by the ,lyons1 ,paris and other ,french stations1 by ,great ,britain1 ,italy1 ,germany and even far off ,russia and ,japan4 ,a long wave set for receiving these stations must be able to tune to wave lengths up to #bj1jjj meters4 ,differing from the way in which the regenerative action of the short wave sets described in the preceding chapter is secured and which depends on a tickler coil and the coupling action of the detector in this long wave set1 ,footnote3 ,all of the short wave and intermediate wave receivers described1 are connected up according to the wiring diagram used by the ,a4 ,h4 ,grebe ,company1 ,richmond ,hill1 ,long ,island1 ,n4 ,y4 this action is obtained by the use of a tickler coil in the plate circuit which is inductively coupled to the grid circuit and this feeds back the necessary amount of current4 ,this is a very good way to connect up the circuits for the reason that3 7#a7 the wiring is simplified1 and 7#b7 it gives a single variable adjustment for the entire range of wave lengths the receptor is intended to cover4 ,the ,parts and ,how to ,connect ,them ,up4--,the two chief features as far as the parts are concerned of this long wave length receiving set are 7#a7 the variable condensers1 and 7#b7 the tuning inductance coils4 ,the variable condenser used in series with the aerial wire system has #bf plates and is equal to a capacitance of 4#jjjh mfd4 which is the normal aerial capacitance4 ,the condenser used in the secondary coil circuit has #ad plates and this is equal to a capacitance of 4#jjjd mfd4 ,there are a number of inductance coils and these are arranged so that they can be connected in or cut out and combinations are thus formed which give a high efficiency and yet allow them to be compactly mounted4 ,the inductance coils of the aerial wire system and those of the secondary coil circuit are practically alike4 ,for wave lengths up to #b1bjj meters bank litz-wound coils are used and these are wound up in #b1 #d and #f banks in order to give the proper degree of coupling and inductance values4 ,where wave lengths of more than #b1bjj meters are to be received coto-coils are used as these are the last word in inductance coil design1 and are especially adapted for medium as well as long wave lengths4 ,footnote3 ,can be had of the ,coto ,coil ,co41 ,providence1 ,r4 ,i4 ,these various coils are cut in and out by means of two five-point switches which are provided with auxiliary levers and contactors for dead-ending the right amount of the coils4 ,in cutting in coils for increased wave lengths1 that is from #aj1jjj to #bj1jjj meters1 all of the coils of the aerial are connected in series as well as all of the coils of the secondary circuit4 ,the connections for a long wave receptor are shown in the wiring diagram in ,fig4 #ei4 ,illustration3 ,fig4 #ei4--,wiring ,diagram ,showing ,long ,wave ,receptor with ,variocouplers and ,bank-wound ,inductance ,coils ,,chapter ,,xiii ,,heterodyne ,,or ,,beat ,,long ,,wave ,,telegraph ,,receiving ,,set ,any of the receiving sets described in the foregoing chapters will respond to either3 7#a7 a wireless telegraph transmitter that uses a spark gap and which sends out periodic electric waves1 or to 7#b7 a wireless telephone transmitter that uses an arc or a vacuum tube oscillator and which sends out continuous electric waves4 ,to receive wireless telegraph signals1 however1 from a transmitter that uses an arc or a vacuum tube oscillator and which sends out continuous waves1 either the transmitter or the receptor must be so constructed that the continuous waves will be broken up into groups of audio frequency and this is done in several different ways4 ,there are four different ways employed at the present time to break up the continuous waves of a wireless telegraph transmitter into groups and these are3 7a7 the heterodyne1 or beat1 method1 in which waves of different lengths are impressed on the received waves and so produces beats2 7b7 the tikker1 or chopper method1 in which the high frequency currents are rapidly broken up2 7c7 the variable condenser method1 in which the movable plates are made to rapidly rotate2 7d7 the tone wheel1 or frequency transformer1 as it is often called1 and which is really a modified form of and an improvement on the tikker4 ,the heterodyne method will be described in this chapter4 ,what the ,heterodyne or ,beat ,method ,is4--,the word heterodyne was coined from the ,greek words heteros which means other1 or different1 and dyne which means power2 in other words it means when used in connection with a wireless receptor that another and different high frequency current is used besides the one that is received from the sending station4 ,in music a beat means a regularly recurrent swelling caused by the reinforcement of a sound and this is set up by the interference of sound waves which have slightly different periods of vibration as1 for instance1 when two tones take place that are not quite in tune with each other4 ,this1 then1 is the principle of the heterodyne1 or beat1 receptor4 ,in the heterodyne1 or beat method1 separate sustained oscillations1 that are just about as strong as those of the incoming waves1 are set up in the receiving circuits and their frequency is just a little higher or a little lower than those that are set up by the waves received from the distant transmitter4 ,the result is that these oscillations of different frequencies interfere and reinforce each other when beats are produced1 the period of which is slow enough to be heard in the headphones1 hence the incoming signals can be heard only when waves from the sending station are being received4 ,a fuller explanation of how this is done will be found in ,chapter ,,xv4 ,the ,autodyne or ,self-,heterodyne ,long-,wave ,receiving ,set4--,this is the simplest type of heterodyne receptor and it will receive periodic waves from spark telegraph transmitters or continuous waves from an arc or vacuum tube telegraph transmitter4 ,in this type of receptor the detector tube itself is made to set up the heterodyne oscillations which interfere with those that are produced by the incoming waves that are a little out of tune with it4 ,with a long wave autodyne1 or self-heterodyne receptor1 as this type is called1 and a two-step audio-frequency amplifier you can clearly hear many of the cableless stations of ,europe and others that send out long waves4 ,for receiving long wave stations1 however1 you must have a long aerial--a single wire #bjj or more feet in length will do--and the higher it is the louder will be the signals4 ,where it is not possible to put the aerial up a hundred feet or more above the ground1 you can use a lower one and still get messages in ,international ,morse fairly strong4 ,the ,parts and ,connections of an ,autodyne1 or ,self-,heterodyne1 ,receiving ,set4--,for this long wave receiving set you will need3 7#a7 one variocoupler with the primary coil wound on the stator and the secondary coil and tickler coil wound on the rotor1 or you can use three honeycomb or other good compact coils of the longest wave you want to receive1 a table of which is given in ,chapter ,,xii2 7#b7 two 4#jja mfd4 variable condensers2 7#c7 one 4#jjje mfd4 variable condenser2 7#d7 one 4#e to #b megohm grid leak resistance2 7#e7 one vacuum tube detector2 7#f7 one ,a battery2 7#g7 one rheostat2 7#h7 one ,b battery2 7#i7 one potentiometer2 7#aj7 one 4#jja mfd4 fixed condenser and 7#aa7 one pair of headphones4 ,for the two-step amplifier you must1 of course1 have besides the above parts the amplifier tubes1 variable condensers1 batteries rheostats1 potentiometers and fixed condensers as explained in ,chapter ,,ix4 ,the connections for the autodyne1 or self-heterodyne1 receiving set are shown in ,fig4 #fj4 ,illustration3 ,fig4 #fj4--,wiring ,diagram of ,long ,wave ,antodyne1 or ,self-,heterodyne ,receptor4 ,the ,separate ,heterodyne ,long ,wave ,receiving ,set4--,this is a better long wave receptor than the self heterodyne set described above for receiving wireless telegraph signals sent out by a continuous long wave transmitter4 ,the great advantage of using a separate vacuum tube to generate the heterodyne oscillations is that you can make the frequency of the oscillations just what you want it to be and hence you can make it a little higher or a little lower than the oscillations set up by the received waves4 ,the ,parts and ,connections of a ,separate ,heterodyne ,long ,wave ,receiving ,set4--,the parts required for this long wave receiving set are3 7#a7 four honeycomb or other good compact inductance coils of the longest wave length that you want to receive2 7#b7 three 4#jja mfd4 variable condensers2 7#c7 one 4#jjje mfd4 variable condenser2 7#d7 one #a megohm grid leak resistance2 7#e7 one vacuum tube detector2 7#f7 one ,a battery2 7#g7 two rheostats2 7#h7 two ,b batteries1 one of which is supplied with taps2 7#i7 one potentiometer2 7#aj7 one vacuum tube amplifier1 for setting up the heterodyne oscillations2 7#aa7 a pair of headphones and 7#ab7 all of the parts for a two-step amplifier as detailed in ,chapter ,,ix1 that is if you are going to use amplifiers4 ,the connections are shown in ,fig4 #fa4 ,illustration3 ,fig4 #fa4--,wiring ,diagram of ,long ,wave ,separate ,heterodyne ,receiving ,set4 ,in using either of these heterodyne receivers be sure to carefully adjust the ,b battery by means of the potentiometer4 ,footnote3 ,the amplifier tube in this case is used as a generator of oscillations4 ,,chapter ,,xiv ,,headphones ,,and ,,loud ,,speakers ,wireless ,headphones4--,a telephone receiver for a wireless receiving set is made exactly on the same principle as an ordinary ,bell telephone receiver4 ,the only difference between them is that the former is made flat and compact so that a pair of them can be fastened together with a band and worn on the head 7when it is called a headset71 while the latter is long and cylindrical so that it can be held to the ear4 ,a further difference between them is that the wireless headphone is made as sensitive as possible so that it will respond to very feeble currents1 while the ordinary telephone receiver is far from being sensitive and will respond only to comparatively large currents4 ,how a ,bell ,telephone ,receiver ,is ,made4--,an ordinary telephone receiver consists of three chief parts and these are3 7#a7 a hard-rubber1 or composition1 shell and cap1 7#b7 a permanent steel bar magnet on one end of which is wound a coil of fine insulated copper wire1 and 7#c7 a soft iron disk1 or diaphragm1 all of which are shown in the cross-section in ,fig4 #fb4 ,the bar magnet is securely fixed inside of the handle so that the outside end comes to within about #a_/cb of an inch of the diaphragm when this is laid on top of the shell and the cap is screwed on4 ,illustration3 ,fig4 #fb4--;,cross-section of ,bell telephone ,receiver4 ,illustration3 original ,underwood and ,underwood4 ,alexander ,graham ,bell1 ,inventor of the ,telephone1 now an ardent ,radio ,enthusiast4 ,the ends of the coil of wire are connected with two binding posts which are in the end of the shell1 but are shown in the picture at the sides for the sake of clearness4 ,this coil usually has a resistance of about #ge ohms and the meaning of the ohmic resistance of a receiver and its bearing on the sensitiveness of it will be explained a little farther along4 ,after the disk1 or diaphragm1 which is generally made of thin1 soft sheet iron that has been tinned or japanned1 ,footnote3 ,a disk of photographic tin-type plate is generally used4 is placed over the end of the magnet1 the cap1 which has a small opening in it1 is screwed on and the receiver is ready to use4 ,how a ,wireless ,headphone ,is ,made4--,for wireless work a receiver of the watch-case type is used and nearly always two such receivers are connected with a headband4 ,it consists of a permanent bar magnet bent so that it will fit into the shell of the receiver as shown at ,a in ,fig4 #fc4 ,illustration3 ,fig4 #fc4--,wireless ,headphone4 ,the ends of this magnet1 which are called poles1 are bent up1 and hence this type is called a bipolar receiver4 ,the magnets are wound with fine insulated wire as before and the diaphragm is held securely in place over them by screwing on the cap4 ,about ,resistance1 ,turns of ,wire and ,sensitivity of ,headphones4--,if you are a beginner in wireless you will hear those who are experienced speak of a telephone receiver as having a resistance of #ge ohms1 #a1jjj ohms1 #b1jjj or #c1jjj ohms1 as the case may be2 from this you will gather that the higher the resistance of the wire on the magnets the more sensitive the receiver is4 ,in a sense this is true1 but it is not the resistance of the magnet coils that makes it sensitive1 in fact1 it cuts down the current1 but it is the number of turns of wire on them that determines its sensitiveness2 it is easy to see that this is so1 for the larger the number of turns the more often will the same current flow round the cores of the magnet and so magnetize them to a greater extent4 ,but to wind a large number of turns of wire close enough to the cores to be effective the wire must be very small and so1 of course1 the higher the resistance will be4 ,now the wire used for winding good receivers is usually ,no4 #dj1 and this has a diameter of 4#jjca inch2 consequently1 when you know the ohmic resistance you get an idea of the number of turns of wire and from this you gather in a general way what the sensitivity of the receiver is4 ,a receiver that is sensitive enough for wireless work should be wound to not less than #a1jjj ohms 7this means each ear phone71 while those of a better grade are wound to as high as #c1jjj ohms for each one4 ,a high-grade headset is shown in ,fig4 #fd4 ,each phone of a headset should be wound to the same resistance1 and these are connected in series as shown4 ,where two or more headsets are used with one wireless receiving set they must all be of the same resistance and connected in series1 that is1 the coils of one head set are connected with the coils of the next head set and so on to form a continuous circuit4 ,illustration3 ,fig4 #fd4--,wireless ,headphone4 ,the ,impedance of ,headphones4--,when a current is flowing through a circuit the material of which the wire is made not only opposes its passage--this is called its ohmic resistance--but a counter-electromotive force to the current is set up due to the inductive effects of the current on itself and this is called impedance4 ,where a wire is wound in a coil the impedance of the circuit is increased and where an alternating current is used the impedance grows greater as the frequency gets higher4 ,the impedance of the magnet coils of a receiver is so great for high frequency oscillations that the latter cannot pass through them2 in other words1 they are choked off4 ,how the ,headphones ,work4--,as you will see from the cross-sections in ,figs4 #fb and #fc there is no connection1 electrical or mechanical1 between the diaphragm and the other parts of the receiver4 ,now when either feeble oscillations1 which have been rectified by a detector1 or small currents from a ,b battery1 flow through the magnet coils the permanent steel magnet is energized to a greater extent than when no current is flowing through it4 ,this added magnetic energy makes the magnet attract the diaphragm more than it would do by its own force4 ,if1 on the other hand1 the current is cut off the pull of the magnet is lessened and as its attraction for the diaphragm is decreased the latter springs back to its original position4 ,when varying currents flow through the coils the diaphragm vibrates accordingly and sends out sound waves4 ,about ,loud ,speakers4--,the simplest acoustic instrument ever invented is the megaphone1 which latter is a ,greek word meaning great sound4 ,it is a very primitive device and our ,indians made it out of birch-bark before ,columbus discovered ,america4 ,in its simplest form it consists of a cone-shaped horn and as the speaker talks into the small end the concentrated sound waves pass out of the large end in whatever direction it is held4 ,now a loud speaker of whatever kind consists of two chief parts and these are3 7#a7 a telephone receiver1 and 7#b7 a megaphone1 or horn as it is called4 ,a loud speaker when connected with a wireless receiving set makes it possible for a room1 or an auditorium1 full of people1 or an outdoor crowd1 to hear what is being sent out by a distant station instead of being limited to a few persons listening-in with headphones4 ,to use a loud speaker you should have a vacuum tube detector receiving set and this must be provided with a one-step amplifier at least4 ,to get really good results you need a two-step amplifier and then energize the plate of the second vacuum tube amplifier with a #ajj volt ,b battery2 or if you have a three-step amplifier then use the high voltage on the plate of the third amplifier tube4 ,amplifying tubes are made to stand a plate potential of #ajj volts and this is the kind you must use4 ,now it may seem curious1 but when the current flows through the coils of the telephone receiver in one direction it gives better results than when it flows through in the other direction2 to find out the way the current gives the best results try it out both ways and this you can do by simply reversing the connections4 ,the ,simplest ,type of ,loud ,speaker4--,this loud speaker1 which is called1 the ,arkay1 ,footnote3 ,made by the ,riley-,klotz ,mfg4 ,co41 ,newark1 ,n4 ,j4 will work on a one- or two-step amplifier4 ,it consists of a brass horn with a curve in it and in the bottom there is an adapter1 or frame1 with a set screw in it so that you can fit in one of your headphones and this is all there is to it4 ,the construction is rigid enough to prevent overtones1 or distortion of speech or music4 ,it is shown in ,fig4 #fe4 ,illustration3 ,fig4 #fe4--;,arkay ,loud ,speaker4 ,another ,simple ,kind of ,loud ,speaker4--,another loud speaker1 see ,fig4 #ff1 is known as the ,amplitone ,footnote3 ,made by the ,american ,pattern1 ,foundry and ,machine ,co41 #hb ,church ,street1 ,n4 ,y4 ,c4 and it likewise makes use of the headphones as the sound producer4 ,this device has a cast metal horn which improves the quality of the sound1 and all you have to do is to slip the headphones on the inlet tubes of the horn and it is ready for use4 ,the two headphones not only give a longer volume of sound than where a single one is used but there is a certain blended quality which results from one phone smoothing out the imperfections of the other4 ,illustration3 ,fig4 #ff4--;,amplitone ,loud ,speaker4 ,a ,third ,kind of ,simple ,loud ,speaker4--,the operation of the ,amplitron1 ,footnote3 ,made by the ,radio ,service ,co41 #aaj ,w4 #djth ,street1 ,n4 ,y4 as this loud speaker is called1 is slightly different from others used for the same purpose4 ,the sounds set up by the headphone are conveyed to the apex of an inverted copper cone which is #g inches long and #aj inches in diameter4 ,here it is reflected by a parabolic mirror which greatly amplifies the sounds4 ,the amplification takes place without distortion1 the sounds remaining as clear and crisp as when projected by the transmitting station4 ,by removing the cap from the receiver the shell is screwed into a receptacle on the end of the loud speaker and the instrument is ready for use4 ,it is pictured in ,fig4 #fg4 ,illustration3 ,fig4 #fg4--;,amplitron ,loud ,speaker4 ,a ,super ,loud ,speaker4--,this loud speaker1 which is known as the ,magnavox ,telemegafone1 was the instrument used by ,lt4 ,herbert ,e4 ,metcalf1 #c1jjj feet in the air1 and which startled the ,city of ,washington on ,april #b1 #aiai1 by repeating ,president ,wilson's ,victory ,loan ,message from an airplane in flight so that it was distinctly heard by #bj1jjj people below4 ,this wonderful achievement was accomplished through the installation of the ,magnavox and amplifiers in front of the ,treasury ,building4 ,every word ,lt4 ,metcalf spoke into his wireless telephone transmitter was caught and swelled in volume by the ,telemegafones below and persons blocks away could hear the message plainly4 ,two kinds of these loud speakers are made and these are3 7#a7 a small loud speaker for the use of operators so that headphones need not be worn1 and 7#b7 a large loud speaker for auditorium and out-door audiences4 ,illustration3 original ,underwood and ,underwood4 ,world's ,largest ,loud ,speaker ever made4 ,installed in ,lytle ,park1 ,cincinnati1 ,ohio1 to permit ,president ,harding's ,address at ,point ,pleasant1 ,ohio1 during the ,grant ,centenary ,celebration to be heard within a radius of one square4 ,either kind may be used with a one- or two-step amplifier or with a cascade of half a dozen amplifiers1 according to the degree of loudness desired4 ,the ,telemegafone itself is not an amplifier in the true sense inasmuch as it contains no elements which will locally increase the incoming current4 ,it does1 however1 transform the variable electric currents of the wireless receiving set into sound vibrations in a most wonderful manner4 ,a telemegafone of either kind is formed of3 7#a7 a telephone receiver of large proportions1 7#b7 a step-down induction coil1 and 7#c7 a #f volt storage battery that energizes a powerful electromagnet which works the diaphragm4 ,an electromagnet is used instead of a permanent magnet and this is energized by a #f-volt storage battery as shown in the wiring diagram at ,a in ,fig4 #fh4 ,one end of the core of this magnet is fixed to the iron case of the speaker and together these form the equivalent of a horseshoe magnet4 ,a movable coil of wire is supported from the center of the diaphragm the edge of which is rigidly held between the case and the small end of the horn4 ,this coil is placed over the upper end of the magnet and its terminals are connected to the secondary of the induction coil4 ,now when the coil is energized by the current from the amplifiers it and the core act like a solenoid in that the coil tends to suck the core into it2 but since the core is fixed and the coil is movable the core draws the coil down instead4 ,the result is that with every variation of the current that flows through the coil it moves up and down and pulls and pushes the diaphragm down and up with it4 ,the large amplitude of the vibrations of the latter set up powerful sound waves which can be heard several blocks away from the horn4 ,in this way then are the faint incoming signals1 speech and music which are received by the amplifying receiving set reproduced and magnified enormously4 ,the ,telemegafone is shown complete at ,b4 ,illustration3 ,fig4 #fh4--,magnavox ,loud ,speaker4 ,,chapter ,,xv ,,operation ,,of ,,vacuum ,,tube ,,receptors ,from the foregoing chapters you have seen that the vacuum tube can be used either as a detector or an amplifier or as a generator of electric oscillations1 as in the case of the heterodyne receiving set4 ,to understand how a vacuum tube acts as a detector and as an amplifier you must first know what electrons are4 ,the way in which the vacuum tube sets up sustained oscillations will be explained in ,chapter ,,xviii in connection with the ,operation of ,vacuum ,tube ,transmitters4 ,what ,electrons ,are4--,science teaches us that masses of matter are made up of molecules1 that each of these is made up of atoms1 and each of these1 in turn1 is made up of a central core of positive particles of electricity surrounded by negative particles of electricity as shown in the schematic diagram1 ,fig4 #fi4 ,the little black circles inside the large circle represent positive particles of electricity and the little white circles outside of the large circle represent negative particles of electricity1 or electrons as they are called4 ,illustration3 ,fig4 #fi4--,schematic ,diagram of an ,atom4 ,it is the number of positive particles of electricity an atom has that determines the kind of an element that is formed when enough atoms of the same kind are joined together to build it up4 ,thus hydrogen1 which is the lightest known element1 has one positive particle for its nucleus1 while uranium1 the heaviest element now known1 has #ib positive particles4 ,now before leaving the atom please note that it is as much smaller than the diagram as the latter is smaller than our solar system4 ,what ,is ,meant by ,ionization4--,a hydrogen atom is not only lighter but it is smaller than the atom of any other element while an electron is more than a thousand times smaller than the atom of which it is a part4 ,now as long as all of the electrons remain attached to the surface of an atom its positive and negative charges are equalized and it will1 therefore1 be neither positive nor negative1 that is1 it will be perfectly neutral4 ,when1 however1 one or more of its electrons are separated from it1 and there are several ways by which this can be done1 the atom will show a positive charge and it is then called a positive ion4 ,in other words a positive ion is an atom that has lost some of its negative electrons while a negative ion is one that has acquired some additional negative electrons4 ,when a number of electrons are being constantly given by the atoms of an element1 which let us suppose is a metal1 and are being attracted to atoms of another element1 which we will say is also a metal1 a flow of electrons takes place between the two oppositely charged elements and form a current of negative electricity as represented by the arrows at ,a in ,fig4 #gj4 ,illustration3 ,fig4 #gj4--;,action of ,two-electrode ,vacuum ,tube4 ,when a stream of electrons is flowing between two metal elements1 as a filament and a plate in a vacuum tube detector1 or an amplifier1 they act as carriers for more negative electrons and these are supplied by a battery as we shall presently explain4 ,it has always been customary for us to think of a current of electricity as flowing from the positive pole of a battery to the negative pole of it and hence we have called this the direction of the current4 ,since the electronic theory has been evolved it has been shown that the electrons1 or negative charges of electricity1 flow from the negative to the positive pole and that the ionized atoms1 which are more positive than negative1 flow in the opposite direction as shown at ,b4 ,how ,electrons are ,separated from ,atoms4--,the next question that arises is how to make a metal throw off some of the electrons of the atoms of which it is formed4 ,there are several ways that this can be done but in any event each atom must be given a good1 hard blow4 ,a simple way to do this is to heat a metal to incandescence when the atoms will bombard each other with terrific force and many of the electrons will be knocked off and thrown out into the surrounding space4 ,but all1 or nearly all1 of them will return to the atoms from whence they came unless a means of some kind is employed to attract them to the atoms of some other element4 ,this can be done by giving the latter piece of metal a positive charge4 ,if now these two pieces of metal are placed in a bulb from which the air has been exhausted and the first piece of metal is heated to brilliancy while the second piece of metal is kept positively electrified then a stream of electrons will flow between them4 ,action of the ,two ,electrode ,vacuum ,tube4--,now in a vacuum tube detector a wire filament1 like that of an incandescent lamp1 is connected with a battery and this forms the hot element from which the electrons are thrown off1 and a metal plate with a terminal wire secured to it is connected to the positive or carbon tap of a dry battery2 now connect the negative or zinc tap of this with one end of a telephone receiver and the other end of this with the terminals of the filament as shown at ,a in ,fig4 #ga4 ,if now you heat the filament and hold the phone to your ear you can hear the current from the ,b battery flowing through the circuit4 ,illustration3 7,a7 and 7,b7 ,fig4 #ga4--;,how a ,two ,electrode ,tube ,acts as a ,relay or a ,detector4 ,illustration3 7,c7 ,fig4 #ga4--,only the ,positive ,part of ,oscillations ,goes through the ,tube4 ,since the electrons are negative charges of electricity they are not only thrown off by the hot wire but they are attracted by the positive charged metal plate and when enough electrons pass1 or flow1 from the hot wire to the plate they form a conducting path and so complete the circuit which includes the filament1 the plate and the ,b or plate battery1 when the current can then flow through it4 ,as the number of electrons that are thrown off by the filament is not great and the voltage of the plate is not high the current that flows between the filament and the plate is always quite small4 ,how the ,two ,electrode ,tube ,acts as a ,detector4--,as the action of a two electrode tube as a detector ,footnote3 ,the three electrode vacuum tube has entirely taken the place of the two electrode type4 is simpler than that of the three electrode vacuum tube we shall describe it first4 ,the two electrode vacuum tube was first made by ,mr4 ,edison when he was working on the incandescent lamp but that it would serve as a detector of electric waves was discovered by ,prof4 ,fleming1 of ,oxford ,university1 ,london4 ,as a matter of fact1 it is not really a detector of electric waves1 but it acts as3 7#a7 a rectifier of the oscillations that are set up in the receiving circuits1 that is1 it changes them into pulsating direct currents so that they will flow through and affect a telephone receiver1 and 7#b7 it acts as a relay and the feeble received oscillating current controls the larger direct current from the ,b battery in very much the same way that a telegraph relay does4 ,this latter relay action will be explained when we come to its operation as an amplifier4 ,we have just learned that when the stream of electrons flow from the hot wire to the cold positive plate in the tube they form a conducting path through which the battery current can flow4 ,now when the electric oscillations surge through the closed oscillation circuit1 which includes the secondary of the tuning coil1 the variable condenser1 the filament and the plate as shown at ,b in ,fig4 #ga the positive part of them passes through the tube easily while the negative part cannot get through1 that is1 the top1 or positive1 part of the wave-form remains intact while the lower1 or negative1 part is cut off as shown in the diagram at ,c4 ,as the received oscillations are either broken up into wave trains of audio frequency by the telegraph transmitter or are modulated by a telephone transmitter they carry the larger impulses of the direct current from the ,b battery along with them and these flow through the headphones4 ,this is the reason the vacuum tube amplifies as well as detects4 ,how the ,three ,electrode ,tube ,acts as a ,detector4--,the vacuum tube as a detector has been made very much more sensitive by the use of a third electrode shown in ,fig4 #gb4 ,in this type of vacuum tube the third electrode1 or grid1 is placed between the filament and the plate and this controls the number of electrons flowing from the filament to the plate2 in passing between these two electrodes they have to go through the holes formed by the grid wires4 ,illustration3 7,a7 and 7,b7 ,fig4 #gb4--;,how the ,positive and ,negative ,voltages of ,oscillations ,act on the ,electrons4 ,illustration3 7,c7 ,fig4 #gb4--;,how the ,three ,electrode ,tube ,acts as a ,detector and ,amplifier4 ,illustration3 7,d7 ,fig4 #gb4--;,how the ,oscillations ,control the ,flow of the ,battery ,current through the ,tube4 ,if now the grid is charged to a higher negative voltage than the filament the electrons will be stopped by the latter1 see ,a1 though some of them will go through to the plate because they travel at a high rate of speed4 ,the higher the negative charge on the grid the smaller will be the number of electrons that will reach the plate and1 of course1 the smaller will be the amount of current that will flow through the tube and the headphones from the ,b battery4 ,on the other hand if the grid is charged positively1 see ,b1 then more electrons will strike the plate than when the grid is not used or when it is negatively charged4 ,but when the three electrode tube is used as a detector the oscillations set up in the circuits change the grid alternately from negative to positive as shown at ,c and hence the voltage of the ,b battery current that is allowed to flow through the detector from the plate to the filament rises and falls in unison with the voltage of the oscillating currents4 ,the way the positive and negative voltages of the oscillations which are set up by the incoming waves1 energize the grid2 how the oscillator tube clips off the negative parts of them1 and1 finally1 how these carry the battery current through the tube are shown graphically by the curves at ,d4 ,how the ,vacuum ,tube ,acts as an ,amplifier4--,if you connect up the filament and the plate of a three electrode tube with the batteries and do not connect in the grid1 you will find that the electrons which are thrown off by the filament will not get farther than the grid regardless of how high the voltage is that you apply to the plate4 ,this is due to the fact that a large number of electrons which are thrown off by the filament strike the grid and give it a negative charge1 and consequently1 they cannot get any farther4 ,since the electrons do not reach the plate the current from the ,b battery cannot flow between it and the filament4 ,now with a properly designed amplifier tube a very small negative voltage on the grid will keep a very large positive voltage on the plate from sending a current through the tube1 and oppositely1 a very small positive voltage on the grid will let a very large plate current flow through the tube2 this being true it follows that any small variation of the voltage from positive to negative on the grid and the other way about will vary a large current flowing from the plate to the filament4 ,in the ,morse telegraph the relay permits the small current that is received from the distant sending station to energize a pair of magnets1 and these draw an armature toward them and close a second circuit when a large current from a local battery is available for working the sounder4 ,the amplifier tube is a variable relay in that the feeble currents set up by the incoming waves constantly and proportionately vary a large current that flows through the headphones4 ,this then is the principle on which the amplifying tube works4 ,the ,operation of a ,simple ,vacuum ,tube ,receiving ,set4--,the way a simple vacuum tube detector receiving set works is like this3 when the filament is heated to brilliancy it gives off electrons as previously described4 ,now when the electric waves impinge on the aerial wire they set up oscillations in it and these surge through the primary coil of the loose coupled tuning coil1 a diagram of which is shown at ,b in ,fig4 #da4 ,the energy of these oscillations sets up oscillations of the same frequency in the secondary coil and these high frequency currents whose voltage is first positive and then negative1 surge in the closed circuit which includes the secondary coil and the variable condenser4 ,at the same time the alternating positive and negative voltage of the oscillating currents is impressed on the grid2 at each change from to - and back again it allows the electrons to strike the plate and then shuts them off2 as the electrons form the conducting path between the filament and the plate the larger direct current from the ,b battery is permitted to flow through the detector tube and the headphones4 ,operation of a ,regenerative ,vacuum ,tube ,receiving ,set4--,by feeding back the pulsating direct current from the ,b battery through the tickler coil it sets up other and stronger oscillations in the secondary of the tuning coil when these act on the detector tube and increase its sensitiveness to a remarkable extent4 ,the regenerative1 or feed back1 action of the receiving circuits used will be easily understood by referring back to ,b in ,fig4 #dg4 ,when the waves set up oscillations in the primary of the tuning coil the energy of them produces like oscillations in the closed circuit which includes the secondary coil and the condenser2 the alternating positive and negative voltages of these are impressed on the grid and these1 as we have seen before1 cause similar variations of the direct current from the ,b battery which acts on the plate and which flows between the latter and the filament4 ,this varying direct current1 however1 is made to flow back through the third1 or tickler coil of the tuning coil and sets up in the secondary coil and circuits other and larger oscillating currents and these augment the action of the oscillations produced by the incoming waves4 ,these extra and larger currents which are the result of the feedback then act on the grid and cause still larger variations of the current in the plate voltage and hence of the current of the ,b battery that flows through the detector and the headphones4 ,at the same time the tube keeps on responding to the feeble electric oscillations set up in the circuits by the incoming waves4 ,this regenerative action of the battery current augments the original oscillations many times and hence produce sounds in the headphones that are many times greater than where the vacuum tube detector alone is used4 ,operation of ,autodyne and ,heterodyne ,receiving ,sets4--,on page #aji ,chapter ,,vii we discussed and at ,a in ,fig4 #cf is shown a picture of two tuning forks mounted on sounding boxes to illustrate the principle of electrical tuning4 ,when a pair of these forks are made to vibrate exactly the same number of times per second there will be a condensation of the air between them and the sound waves that are sent out will be augmented4 ,but if you adjust one of the forks so that it will vibrate #bef times a second and the other fork so that it will vibrate #bfj times a second then there will be a phase difference between the two sets of waves and the latter will augment each other #d times every second and you will hear these rising and falling sounds as beats4 ,now electric oscillations set up in two circuits that are coupled together act in exactly the same way as sound waves produced by two tuning forks that are close to each other4 ,since this is true if you tune one of the closed circuits so that the oscillations in it will have a frequency of a #a1jjj1jjj and tune the other circuit so that the oscillations in it have a frequency of #a1jja1jjj a second then the oscillations will augment each other #a1jjj times every second4 ,as these rising and falling currents act on the pulsating currents from the ,b battery which flow through the detector tube and the headphones you will hear them as beats4 ,a graphic representation of the oscillating currents set up by the incoming waves1 those produced by the heterodyne oscillator and the beats they form is shown in ,fig4 #gc4 ,to produce these beats a receptor can use3 7#a7 a single vacuum tube for setting up oscillations of both frequencies when it is called an autodyne1 or self-heterodyne receptor1 or 7#b7 a separate vacuum tube for setting up the oscillations for the second circuit when it is called a heterodyne receptor4 ,illustration3 ,fig4 #gc4--;,how the ,heterodyne ,receptor ,works4 ,the ,autodyne1 or ,self-,heterodyne ,receiving ,set4--,where only one vacuum tube is used for producing both frequencies you need only a regenerative1 or feed-back receptor2 then you can tune the aerial wire system to the incoming waves and tune the closed circuit of the secondary coil so that it will be out of step with the former by #a1jjj oscillations per second1 more or less1 the exact number does not matter in the least4 ,from this you will see that any regenerative set can be used for autodyne1 or self-heterodyne1 reception4 ,the ,separate ,heterodyne ,receiving ,set4--,the better way1 however1 is to use a separate vacuum tube for setting up the heterodyne oscillations4 ,the latter then act on the oscillations that are produced by the incoming waves and which energize the grid of the detector tube4 ,note that the vacuum tube used for producing the heterodyne oscillations is a generator of electric oscillations2 the latter are impressed on the detector circuits through the variable coupling1 the secondary of which is in series with the aerial wire as shown in ,fig4 #gd4 ,the way in which the tube acts as a generator of oscillations will be told in ,chapter ,,xviii4 ,illustration3 ,fig4 #gd4--,separate ,heterodyne ,oscillator4 ,,chapter ,,xvi ,,continuous ,,wave ,,telegraph ,,transmitting ,,sets ,,with ,,direct ,,current ,in the first part of this book we learned about spark-gap telegraph sets and how the oscillations they set up are damped and the waves they send out are periodic4 ,in this and the next chapter we shall find out how vacuum tube telegraph transmitters are made and how they set up oscillations that are sustained and radiate waves that are continuous4 ,sending wireless telegraph messages by continuous waves has many features to recommend it as against sending them by periodic waves and among the most important of these are that the transmitter can be3 7#a7 more sharply tuned1 7#b7 it will send signals farther with the same amount of power1 and 7#c7 it is noiseless in operation4 ,the disadvantageous features are that3 7#a7 a battery current is not satisfactory1 7#b7 its circuits are somewhat more complicated1 and 7#c7 the oscillator tubes burn out occasionally4 ,there is1 however1 a growing tendency among amateurs to use continuous wave transmitters and they are certainly more up-to-date and interesting than spark gap sets4 ,now there are two practical ways by which continuous waves can be set up for sending either telegraphic signals or telephonic speech and music and these are with3 7a7 an oscillation arc lamp1 and 7b7 a vacuum tube oscillator4 ,the oscillation arc was the earliest known way of setting up sustained oscillations1 and it is now largely used for commercial high power1 long distance work4 ,but since the vacuum tube has been developed to a high degree of efficiency and is the scheme that is now in vogue for amateur stations we shall confine our efforts here to explaining the apparatus necessary and how to wire the various parts together to produce several sizes of vacuum tube telegraph transmitters4 ,sources of ,current for ,telegraph ,transmitting ,sets4--,differing from a spark-gap transmitter you cannot get any appreciable results with a low voltage battery current to start with4 ,for a purely experimental vacuum tube telegraph transmitter you can use enough ,b batteries to operate it but the current strength of these drops so fact when they are in use1 that they are not at all satisfactory for the work4 ,you can1 however1 use #aaj volt direct current from a lighting circuit as your initial source of power to energize the plate of the vacuum tube oscillator of your experimental transmitter4 ,where you have a #aaj volt direct current lighting service in your home and you want a higher voltage for your plate1 you will then have to use a motor-generator set and this costs money4 ,if you have #aaj volt alternating current lighting service at hand your troubles are over so far as cost is concerned for you can step it up to any voltage you want with a power transformer4 ,in this chapter will be shown how to use a direct current for your source of initial power and in the next chapter how to use an alternating current for the initial power4 ,an ,experimental ,continuous ,wave ,telegraph ,transmitter4--,you will remember that in ,chapter ,,xv we learned how the heterodyne receiver works and that in the separate heterodyne receiving set the second vacuum tube is used solely to set up oscillations4 ,now while this extra tube is used as a generator of oscillations these are1 of course1 very weak and hence a detector tube cannot be used to generate oscillations that are useful for other purposes than heterodyne receptors and measurements4 ,there is a vacuum tube amplifier ,footnote3 ,this is the radiation ,,uv-#bja1 made by the ,radio ,corporation of ,america1 ,woolworth ,bldg41 ,new ,york ,city4 made that will stand a plate potential of #ajj volts1 and this can be used as a generator of oscillations by energizing it with a #aaj volt direct current from your lighting service4 ,or in a pinch you can use five standard ,b batteries to develop the plate voltage1 but these will soon run down4 ,but whatever you do1 never use a current from a lighting circuit on a tube of any kind that has a rated plate potential of less than #ajj volts4 ,the ,apparatus ,you ,need4--,for this experimental continuous wave telegraph transmitter get the following pieces of apparatus3 7#a7 one single coil tuner with three clips2 7#b7 one 4#jjb mfd4 fixed condenser2 7#c7 three 4#jja mfd4 condensers2 7#d7 one adjustable grid leak2 7#e7 one hot-wire ammeter2 7#f7 one buzzer2 7#g7 one dry cell2 7#h7 one telegraph key2 7#i7 one #ajj volt plate vacuum tube amplifier2 7#aj7 one #f volt storage battery2 7#aa7 one rheostat2 7#ab7 one oscillation choke coil2 7#ac7 one panel cut-out with a single-throw1 double-pole switch1 and a pair of fuse sockets on it4 ,the ,tuning ,coil4--,you can either make this tuning coil or buy one4 ,to make it get two disks of wood #c_/d-;inch thick and #e inches in diameter and four strips of hard wood1 or better1 hard rubber or composition strips1 such as bakelite1 #a_/b-;inch thick1 #a inch wide and #e-c_/d inches long1 and screw them to the disks as shown at ,a in ,fig4 #ge4 ,now wrap on this form about #be turns of ,no4 #h or #aj1 ,brown and ,sharpe gauge1 bare copper wire with a space of #a_/h-;inch between each turn4 ,get three of the smallest size terminal clips1 see ,b1 and clip them on to the different turns1 when your tuning coil is ready for use4 ,you can buy a coil of this kind for #d4jj or #e4jj4 ,the ,condensers4--,for the aerial series condenser get one that has a capacitance of 4#jjb mfd4 and that will stand a potential of #c1jjj volts4 ,footnote3 ,the ,u ,c-#ajad ,faradon condenser made by the ,radio ,corporation of ,america will serve the purpose4 ,it is shown at ,c4 ,the other three condensers1 see ,d1 are also of the fixed type and may have a capacitance of 4#jja mfd42 ,footnote3 ,list ,no4 #bff2 fixed receiving condenser1 sold by the ,manhattan ,electrical ,supply ,co4 the blocking condenser should preferably have a capacitance of #a_/b a mfd4 ,in these condensers the leaves of the sheet metal are embedded in composition4 ,the aerial condenser will cost you #b4jj and the others #ge cents each4 ,illustration3 7,a7 ,fig4 #ge4--;,apparatus for ,experimental ,c4 ,w4 ,telegraph ,transmitter4 ,illustration3 ,fig4 #ge4--;,apparatus for ,experimental ,c4 ,w4 ,telegraph ,transmitter4 ,the ,aerial ,ammeter4--,this instrument is also called a hot-wire ammeter because the oscillating currents flowing through a piece of wire heat it according to their current strength and as the wire contracts and expands it moves a needle over a scale4 ,the ammeter is connected in the aerial wire system1 either in the aerial side or the ground side--the latter place is usually the most convenient4 ,when you tune the transmitter so that the ammeter shows the largest amount of current surging in the aerial wire system you can consider that the oscillation circuits are in tune4 ,a hot-wire ammeter reading to #b4e amperes will serve your needs1 it costs #f4jj and is shown at ,e in ,fig4 #ge4 ,illustration3 ,united ,states ,naval ,high ,power ,station1 ,arlington ,va4 ,general view of ,power ,room4 ,at the left can be seen the ,control ,switchboards1 and overhead1 the great #cj ,k4,w4 ,arc ,transmitter with ,accessories4 ,the ,buzzer and ,dry ,cell4--,while a heterodyne1 or beat1 receptor can receive continuous wave telegraph signals an ordinary crystal or vacuum tube detector receiving set cannot receive them unless they are broken up into trains either at the sending station or at the receiving station1 and it is considered the better practice to do this at the former rather than at the latter station4 ,for this small transmitter you can use an ordinary buzzer as shown at ,f4 ,a dry cell or two must be used to energize the buzzer4 ,you can get one for about #ge cents4 ,the ,telegraph ,key4--,any kind of a telegraph key will serve to break up the trains of sustained oscillations into dots and dashes4 ,the key shown at ,g is mounted on a composition base and is the cheapest key made1 costing #a4ej4 ,the ,vacuum ,tube ,oscillator4--,as explained before you can use any amplifying tube that is made for a plate potential of #ajj volts4 ,the current required for heating the filament is about #a ampere at #f volts4 ,a porcelain socket should be used for this tube as it is the best insulating material for the purpose4 ,an amplifier tube of this type is shown at ,h and costs #f4ej4 ,the ,storage ,battery4--,a storage battery is used to heat the filament of the tube1 just as it is with a detector tube1 and it can be of any make or capacity as long as it will develop #f volts4 ,the cheapest #f volt storage battery on the market has a #bj to #dj ampere-hour capacity and sells for #ac4jj4 ,the ,battery ,rheostat4--,as with the receptors a rheostat is needed to regulate the current that heats the filament4 ,a rheostat of this kind is shown at ,i and is listed at #a4be4 ,the ,oscillation ,choke ,coil4--,this coil is connected in between the oscillation circuits and the source of current which feeds the oscillator tube to keep the oscillations set up by the latter from surging back into the service wires where they would break down the insulation4 ,you can make an oscillation choke coil by winding say #ajj turns of ,no4 #bh ,brown and ,sharpe gauge double cotton covered magnet wire on a cardboard cylinder #b inches in diameter and #b-a_/b inches long4 ,transmitter ,connectors4--,for connecting up the different pieces of apparatus of the transmitter it is a good scheme to use copper braid2 this is made of braided copper wire in three sizes and sells for #g1ae and #bj cents a foot respectively4 ,a piece of it is pictured at ,j4 ,the ,panel ,cut-,out4--,this is used to connect the cord of the #aaj-volt lamp socket with the transmitter4 ,it consists of a pair of plug cutouts and a single-throw1 double-pole switch mounted on a porcelain base as shown at ,k4 ,in some localities it is necessary to place these in an iron box to conform to the requirements of the fire underwriters4 ,connecting ,up the ,transmitting ,apparatus4--,the way the various pieces of apparatus are connected together is shown in the wiring diagram4 ,fig4 #gf4 ,begin by connecting one post of the ammeter with the wire that leads to the aerial and the other post of it to one end of the tuning coil2 connect clip #a to one terminal of the 4#jjb mfd4 #c1jjj volt aerial condenser and the other post of this with the ground4 ,illustration3 ,fig4 #gf--;,experimental ,c4,w4 ,telegraph ,transmitter ,now connect the end of the tuning coil that leads to the ammeter with one end of the 4#jja mfd4 grid condenser and the other end of this with the grid of the vacuum tube4 ,connect the telegraph key1 the buzzer and the dry cell in series and then shunt them around the grid condenser4 ,next connect the plate of the tube with one end of the 4#jja mfd4 blocking condenser and the other end of this with the clip #b on the tuning coil4 ,connect one end of the filament with the or positive electrode of the storage battery1 the - or negative electrode of this with one post of the rheostat and the other post of the latter with the other end of the filament2 then connect clip #c with the or positive side of the storage battery4 ,this done connect one end of the choke coil to the conductor that leads to the plate and connect the other end of the choke coil to one of the taps of the switch on the panel cut-out4 ,connect the or positive electrode of the storage battery to the other switch tap and between the switch and the choke coil connect the protective condenser across the #aaj volt feed wires4 ,finally connect the lamp cord from the socket to the plug fuse taps when your experimental continuous wave telegraph transmitter is ready to use4 ,a #ajj ,mile ,c4 ,w4 ,telegraph ,transmitter4--,here is a continuous wave telegraph transmitter that will cover distances up to #ajj miles that you can rely on4 ,it is built on exactly the same lines as the experimental transmitter just described1 but instead of using a #ajj volt plate amplifier as a makeshift generator of oscillations it employs a vacuum tube made especially for setting up oscillations and instead of having a low plate voltage it is energized with #cej volts4 ,the ,apparatus ,you ,need4--,for this transmitter you require3 7#a7 one oscillation transformer2 7#b7 one hot-wire ammeter2 7#c7 one aerial series condenser2 7#d7 one grid leak resistance2 7#e7 one chopper2 7#f7 one key circuit choke coil2 7#g7 one #e watt vacuum tube oscillator2 7#h7 one #f volt storage battery2 7#i7 one battery rheostat2 7#aj7 one battery voltmeter2 7#aa7 one blocking condenser2 7#ab7 one power circuit choke coil1 and 7#ac7 one motor-generator4 ,the ,oscillation ,transformer4--,the tuning coil1 or oscillation transformer as this one is called1 is a conductively coupled tuner--that is1 the primary and secondary coils form one continuous coil instead of two separate coils4 ,this tuner is made up of #be turns of thin copper strip1 #c_/h inch wide and with its edges rounded1 and this is secured to a wood base as shown at ,a in ,fig4 #gg4 ,it is fitted with one fixed tap and three clips to each of which a length of copper braid is attached4 ,it has a diameter of #f-a_/d inches1 a height of #g-g_/h inches and a length of #i-c_/h inches1 and it costs #aa4jj4 ,illustration3 ,fig4 #gg4--;,apparatus of #ajj ,mile ,c4 ,w4 ,telegraph ,transmitter4 ,the ,aerial ,condenser4--,this condenser is made up of three fixed condensers of different capacitances1 namely 4#jjjc1 4#jjjd and 4#jjje mfd41 and these are made to stand a potential of #gejj volts4 ,the condenser is therefore adjustable and1 as you will see from the picture ,b1 it has one terminal wire at one end and three terminal wires at the other end so that one1 two or three condensers can be used in series with the aerial4 ,a condenser of this kind costs #e4dj4 ,the ,aerial ,ammeter4--,this is the same kind of a hot-wire ammeter already described in connection with the experimental set1 but it reads to #e amperes4 ,the ,grid and ,blocking ,condensers4--,each of these is a fixed condenser of 4#jjb mfd4 capacitance and is rated to stand #c1jjj volts4 ,it is made like the aerial condenser but has only two terminals4 ,it costs #b4jj4 ,the ,key ,circuit ,apparatus4--,this consists of3 7#a7 the grid leak2 7#b7 the chopper2 7#c7 the choke coil1 and 7#d7 the key4 ,the grid leak is connected in the lead from the grid to the aerial to keep the voltage on the grid at the right potential4 ,it has a resistance of #ejjj ohms with a mid-tap at #bejj ohms as shown at ,c4 ,it costs #b4jj4 ,the chopper is simply a rotary interrupter driven by a small motor4 ,it comprises a wheel of insulating material in which #cj or more metal segments are set in an insulating disk as shown at ,d4 ,a metal contact called a brush is fixed on either side of the wheel4 ,it costs about #g4jj and the motor to drive it is extra4 ,the choke coil is wound up of about #bej turns of ,no4 #cj ,brown and ,sharpe gauge cotton covered magnet wire on a spool which has a diameter of #b inches and a length of #c-a_/d inches4 ,the #e ,watt ,oscillator ,vacuum ,tube4--,this tube is made like the amplifier tube described for use with the preceding experimental transmitter1 but it is larger1 has a more perfect vacuum1 and will stand a plate potential of #cej volts while the plate current is 4#jde ampere4 ,the filament takes a current of a little more than #b amperes at #g4e volts4 ,a standard #d-tap base is used with it4 ,the tube costs #h4jj and the porcelain base is #a4jj extra4 ,it is shown at ,e4 ,the ,storage ,battery and ,rheostat4--,this must be a #e-;cell battery so that it will develop #aj volts4 ,a storage battery of any capacity can be used but the lowest priced one costs about #bb4jj4 ,the rheostat for regulating the battery current is the same as that used in the preceding experimental transmitter4 ,the ,filament ,voltmeter4--,to get the best results it is necessary that the voltage of the current which heats the filament be kept at the same value all of the time4 ,for this transmitter a direct current voltmeter reading from #j to #ae volts is used4 ,it is shown at ,f and costs #g4ej4 ,the ,oscillation ,choke ,coil4--,this is made exactly like the one described in connection with the experimental transmitter4 ,the ,motor-,generator ,set4--,where you have only a #aaj or a #bbj volt direct current available as a source of power you need a motor-generator to change it to #cej volts1 and this is an expensive piece of apparatus4 ,it consists of a single armature core with a motor winding and a generator winding on it and each of these has its own commutator4 ,where the low voltage current flows into one of the windings it drives its as a motor and this in turn generates the higher voltage current in the other winding4 ,get a #ajj watt #cej volt motor-generator2 it is shown at ,f and costs about #ge4jj4 ,the ,panel ,cut-,out4--,this switch and fuse block is the same as that used in the experimental set4 ,the ,protective ,condenser4--,this is a fixed condenser having a capacitance of #a mfd4 and will stand #gej volts4 ,it costs #b4jj4 ,connecting ,up the ,transmitting ,apparatus4--,from all that has gone before you have seen that each piece of apparatus is fitted with terminal1 wires1 taps or binding posts4 ,to connect up the parts of this transmitter it is only necessary to make the connections as shown in the wiring diagram ,fig4 #gh4 ,illustration3 ,fig4 #gh4--e to #ej ,watt ,c4 ,w4 ,telegraph ,transmitter4 7,with ,single ,oscillation ,tube47 ,a #bjj ,mile ,c4 ,w4 ,telegraph ,transmitter4--,to make a continuous wave telegraph transmitter that will cover distances up to #bjj miles all you have to do is to use two #e watt vacuum tubes in parallel1 all of the rest of the apparatus being exactly the same4 ,connecting the oscillator tubes up in parallel means that the two filaments are connected across the leads of the storage battery1 the two grids on the same lead that goes to the aerial and the two plates on the same lead that goes to the positive pole of the generator4 ,where two or more oscillator tubes are used only one storage battery is needed1 but each filament must have its own rheostat4 ,the wiring diagram ,fig4 #gi shows how the two tubes are connected up in parallel4 ,illustration3 ,fig4 #gi4--bjj ,mile ,c4,w4 ,telegraph ,transmitter 7,with ,two ,tubes in ,parallel47 ,a #ejj ,mile ,c4 ,w4 ,telegraph ,transmitter4--,for sending to distances of over #bjj miles and up to #ejj miles you can use either3 7#a7 three or four #e watt oscillator tubes in parallel as described above1 or 7#b7 one #ej watt oscillator tube4 ,much of the apparatus for a #ej watt tube set is exactly the same as that used for the #e watt sets4 ,some of the parts1 however1 must be proportionately larger though the design all the way through remains the same4 ,the ,apparatus and ,connections4--,the aerial series condenser1 the blocking condenser1 the grid condenser1 the telegraph key1 the chopper1 the choke coil in the key circuit1 the filament voltmeter and the protective condenser in the power circuit are identical with those described for the #e watt transmitting set4 ,the #ej ,watt ,vacuum ,tube ,oscillator4--,this is the size of tube generally used by amateurs for long distance continuous wave telegraphy4 ,a single tube will develop #b to #c amperes in your aerial4 ,the filament takes a #aj volt current and a plate potential of #a1jjj volts is needed4 ,one of these tubes is shown in ,fig4 #hj and the cost is #cj4jj4 ,a tube socket to fit it costs #b4ej extra4 ,illustration3 ,fig4 #hj4--ej ,watt ,oscillator ,vacuum ,tube4 ,the ,aerial ,ammeter4--,this should read to #e amperes and the cost is #f4be4 ,the ,grid ,leak ,resistance4--,it has the same resistance1 namely #e1jjj ohms as the one used with the #e watt tube transmitter1 but it is a little larger4 ,it is listed at #a4fe4 ,the ,oscillation ,choke ,coil4--,the choke coil in the power circuit is made of about #bfj turns of ,no4 #cj ,b4 ,s4 cotton covered magnet wire wound on a spool #b-a_/d inches in diameter and #c-a_/d inches long4 ,the ,filament ,rheostat4--,this is made to take care of a #aj volt current and it costs #aj4jj4 ,the ,filament ,storage ,battery4--,this must develop #ab volts and one having an output of #dj ampere-hours costs about #be4jj4 ,the ,protective ,condenser4--,this condenser has a capacitance of #a mfd4 and costs #b4jj4 ,the ,motor-,generator4--,where you use one #ej watt oscillator tube you will need a motor-generator that develops a plate potential of #ajjj volts and has an output of #bjj watts4 ,this machine will stand you about #ajj4jj4 ,the different pieces of apparatus for this set are connected up exactly the same as shown in the wiring diagram in ,fig4 #gh4 ,a #ajjj ,mile ,c4 ,w4 ,telegraph ,transmitter4--,all of the parts of this transmitting set are the same as for the #ejj mile transmitter just described except the motor generator and while this develops the same plate potential1 i4e41 #a1jjj volts1 it must have an output of #ejj watts2 it will cost you in the neighborhood of #age4jj4 ,for this long distance transmitter you use two #ej watt oscillator tubes in parallel and all of the parts are connected together exactly the same as for the #bjj mile transmitter shown in the wiring diagram in ,fig4 #gi4 ,,chapter ,,xvii ,,continuous ,,wave ,,telegraph ,,transmitting ,,sets ,,with ,,alternating ,,current ,within the last few years alternating current has largely taken the place of direct current for light1 heat and power purposes in and around towns and cities and if you have alternating current service in your home you can install a long distance continuous wave telegraph transmitter with very little trouble and at a comparatively small expense4 ,a #ajj ,mile ,c4 ,w4 ,telegraph ,transmitting ,set4--,the principal pieces of apparatus for this transmitter are the same as those used for the #ajj ,mile ,continuous ,wave ,telegraph ,transmitting ,set described and pictured in the preceding chapter which used direct current1 except that an alternating current power transformer is employed instead of the more costly motor-generator4 ,the ,apparatus ,required4--,the various pieces of apparatus you will need for this transmitting set are3 7#a7 one hot-wire ammeter for the aerial as shown at ,e in ,fig4 #ge1 but which reads to #e amperes instead of to #b4e amperes2 7#b7 one tuning coil as shown at ,a in ,fig4 #gg2 7#c7 one aerial condenser as shown at ,b in ,fig4 #gg2 7#d7 one grid leak as shown at ,c in ,fig4 #gg2 7#e7 one telegraph key as shown at ,g in ,fig4 #ge2 7#f7 one grid condenser1 made like the aerial condenser but having only two terminals2 7#g7 one #e watt oscillator tube as shown at ,e in ,fig4 #gg2 7#h7 one 4#jjb mfd4 #c1jjj volt by-pass condenser1 made like the aerial and grid condensers2 7#i7 one pair of choke coils for the high voltage secondary circuit2 7#aj7 one milli-ammeter2 7#aa7 one ,a4 ,c4 power transformer2 7#ab7 one rheostat as shown at ,i in ,fig4 #ge1 and 7#ac7 one panel cut-out as shown at ,k in ,fig4 #ge4 ,the ,choke ,coils4--,each of these is made by winding about #ajj turns of ,no4 #bh1 ,brown and ,sharpe gauge1 cotton covered magnet wire on a spool #b inches in diameter and #b-a_/b inches long1 when it will have an inductance of about #j4e millihenry ,footnote3 ,a millihenry is #a_/ajjjth part of a henry4 at #a1jjj cycles4 ,the ,milli-ammeter4--,this is an alternating current ammeter and reads from #j to #bej milliamperes2 ,footnote3 ,a milliampere is the #a_/ajjjth part of an ampere4 and is used for measuring the secondary current that energizes the plate of the oscillator tube4 ,it looks like the aerial ammeter and costs about #g4ej4 ,the ,a4 ,c4 ,power ,transformer4--,differing from the motor generator set the power transformer has no moving parts4 ,for this transmitting set you need a transformer that has an input of #cbe volts4 ,it is made to work on a #ej to #fj cycle current at #ajb4e to #aae volts1 which is the range of voltage of the ordinary alternating lighting current4 ,this adjustment for voltage is made by means of taps brought out from the primary coil to a rotary switch4 ,the high voltage secondary coil which energizes the plate has an output of #age watts and develops a potential of from #cej to #a1ajj volts4 ,the low voltage secondary coil which heats the filament has an output of #age watts and develops #g4e volts4 ,this transformer1 which is shown in ,fig4 #ha1 is large enough to take care of from one to four #e watt oscillator tubes4 ,it weighs about #ae pounds and sells for #be4jj4 ,illustration3 ,fig4 #ha4--;,alternation ,current ,power ,transformer4 7,for ,c4 ,w4 ,telegraphy and ,wireless ,telephony47 ,illustration3 ,the ,transformer and ,tuner of the ,world's ,largest ,radio ,station4 ,owned by the ,radio ,corporation of ,america at ,rocky ,point near ,port ,jefferson ,l4,i4 ,connecting ,up the ,apparatus4--,the wiring diagram ,fig4 #hb shows clearly how all of the connections are made4 ,it will be observed that a storage battery is not needed as the secondary coil of the transformer supplies the current to heat the filament of the oscillator4 ,the filament voltmeter is connected across the filament secondary coil terminals1 while the plate milli-ammeter is connected to the mid-taps of the plate secondary coil and the filament secondary coil4 ,illustration3 ,fig4 #hb4 ,wiring ,diagram for #bjj to #ejj ,mile ,c4,w4 ,telegraph ,transmitting ,set4 7,with ,alternating ,current7 ,a #bjj to #ejj ,mile ,c4 ,w4 ,telegraph ,transmitting ,set4--,distances of from #bjj to #ejj miles can be successfully covered with a telegraph transmitter using two1 three or four #e watt oscillator tubes in parallel4 ,the apparatus needed is identical with that used for the #ajj mile transmitter just described4 ,the tubes are connected in parallel as shown in the wiring diagram in ,fig4 #hc4 ,illustration3 ,fig4 #hc4--,wiring ,diagram for #ejj to #ajjj ,mile ,c4 ,w4 ,telegraph ,transmitter4 ,a #ejj to #a1jjj ,mile ,c4 ,w4 ,telegraph ,transmitting ,set4--,with the apparatus described for the above set and a single #ej watt oscillator tube a distance of upwards of #ejj miles can be covered1 while with two #ej watt oscillator tubes in parallel you can cover a distance of #a1jjj miles without difficulty1 and nearly #b1jjj miles have been covered with this set4 ,the ,apparatus ,required4--,all of the apparatus for this ,c4 ,w4 telegraph transmitting set is the same as that described for the #ajj and #bjj mile sets but you will need3 7#a7 one or two #ej watt oscillator tubes with sockets2 7#b7 one key condenser that has a capacitance of #a mfd41 and a rated potential of #a1gej volts2 7#c7 one #j to #ejj milli-ammeter2 7#d7 one aerial ammeter reading to #e amperes1 and 7#e7 an ,a4 ,c4 power transformer for one or two #ej watt tubes4 ,illustration3 ,broadcasting ,government ,reports by ,wireless from ,washington4 ,this shows ,mr4 ,gale at work with his set in the ,post ,office ,department4 ,the ,alternating ,current ,power ,transformer4--,this power transformer is made exactly like the one described in connection with the preceding #ajj mile transmitter and pictured in ,fig4 #ha1 but it is considerably larger4 ,like the smaller one1 however1 it is made to work with a #ej to #fj cycle current at #ajb4e to #aae volts and1 hence1 can be used with any ,a4 ,c4 lighting current4 ,it has an input of #gej volts and the high voltage secondary coil which energizes the plate has an output of #dej watts and develops #a1ejj to #c1jjj volts4 ,the low voltage secondary coil which heats the filament develops #aj4e volts4 ,this transformer will supply current for one or two #ej-watt oscillator tubes and it costs about #dj4jj4 ,connecting ,up the ,apparatus4--,where a single oscillator tube is used the parts are connected as shown in ,fig4 #hb1 and where two tubes are connected in parallel the various pieces of apparatus are wired together as shown in ,fig4 #hc4 ,the only difference between the #e watt tube transmitter and the #ej watt tube transmitter is in the size of the apparatus with one exception2 where one or two #ej watt tubes are used a second condenser of large capacitance 7#a mfd47 is placed in the grid circuit and the telegraph key is shunted around it as shown in the diagram ,fig4 #hc4 ,,chapter ,,xviii ,,wireless ,,telephone ,,transmitting ,,sets ,,with ,,direct ,,and ,,alternating ,,currents ,in time past the most difficult of all electrical apparatus for the amateur to make1 install and work was the wireless telephone4 ,this was because it required a direct current of not less than #ejj volts to set up the sustained oscillations and all ordinary direct current for lighting purposes is usually generated at a potential of #aaj volts4 ,now as you know it is easy to step-up a #aaj volt alternating current to any voltage you wish with a power transformer but until within comparatively recent years an alternating current could not be used for the production of sustained oscillations for the very good reason that the state of the art had not advanced that far4 ,in the new order of things these difficulties have all but vanished and while a wireless telephone transmitter still requires a high voltage direct current to operate it this is easily obtained from #aaj volt source of alternating current by means of vacuum tube rectifiers4 ,the pulsating direct currents are then passed through a filtering reactance coil1 called a reactor1 and one or more condensers1 and these smooth them out until they approximate a continuous direct current4 ,the latter is then made to flow through a vacuum tube oscillator when it is converted into high frequency oscillations and these are varied1 or modulated1 as it is called1 by a microphone transmitter such as is used for ordinary wire telephony4 ,the energy of these sustained modulated oscillations is then radiated into space from the aerial in the form of electric waves4 ,the distance that can be covered with a wireless telephone transmitter is about one-fourth as great as that of a wireless telegraph transmitter having the same input of initial current1 but it is long enough to satisfy the most enthusiastic amateur4 ,for instance with a wireless telephone transmitter where an amplifier tube is used to set up the oscillations and which is made for a plate potential of #ajj volts1 distances up to #aj or #ae miles can be covered4 ,with a single #e watt oscillator tube energized by a direct current of #cej volts from either a motor-generator or from a power transformer 7after it has been rectified and smoothed out7 speech and music can be transmitted to upwards of #be miles4 ,where two #e watt tubes connected in parallel are used wireless telephone messages can be transmitted to distances of #dj or #ej miles4 ,further1 a single #ej watt oscillator tube will send to distances of #ej to #ajj miles while two of these tubes in parallel will send from #ajj to #bjj miles4 ,finally1 where four or five oscillator tubes are connected in parallel proportionately greater distances can be covered4 ,a ,short ,distance ,wireless ,telephone ,transmitting ,set-,with #aaj ,volt ,direct ,lighting ,current4--,for this very simple1 short distance wireless telephone transmitting set you need the same apparatus as that described and pictured in the beginning of ,chapter ,,xvi for a ,short ,distance ,c4 ,w4 ,telegraph ,transmitter1 except that you use a microphone transmitter instead of a telegraph key4 ,if you have a #aaj volt direct lighting current in your home you can put up this short distance set for very little money and it will be well worth your while to do so4 ,the ,apparatus ,you ,need4--,for this set you require3 7#a7 one tuning coil as shown at ,a and ,b in ,fig4 #ge2 7#b7 one aerial ammeter as shown at ,c in ,fig4 #ge2 7#c7 one aerial condenser as shown at ,c in ,fig4 #ge2 7#d7 one grid1 blocking and protective condenser as shown at ,d in ,fig4 #ge2 7#e7 one grid leak as shown at ,c in ,fig4 #gg2 7#f7 one vacuum tube amplifier which is used as an oscillator2 7#g7 one #f volt storage battery2 7#h7 one rheostat as shown at ,i in ,fig4 #ge2 7#i7 one oscillation choke coil2 7#aj7 one panel cut-out as shown at ,k in ,fig4 #ge and an ordinary microphone transmitter4 ,the ,microphone ,transmitter4--,the best kind of a microphone to use with this and other telephone transmitting sets is a ,western ,electric ,no4 #bhd-,w4 ,footnote3 ,made by the ,western ,electric ,company1 ,chicago1 ,ill4 ,this is known as a solid back transmitter and is the standard commercial type used on all long distance ,bell telephone lines4 ,it articulates sharply and distinctly and there are no current variations to distort the wave form of the voice and it will not buzz or sizzle4 ,it is shown in ,fig4 #hd and costs #b4jj4 ,any other good microphone transmitter can be used if desired4 ,illustration3 ,fig4 #hd4--,standard ,microphone ,transmitter4 ,connecting ,up the ,apparatus4--,begin by connecting the leading-in wire with one of the terminals of the microphone transmitter1 as shown in the wiring diagram ,fig4 #he1 and the other terminal of this to one end of the tuning coil4 ,now connect clip #a of the tuning coil to one of the posts of the hot-wire ammeter1 the other post of this to one end of aerial condenser and1 finally1 the other end of the latter with the water pipe or other ground4 ,the microphone can be connected in the ground wire and the ammeter in the aerial wire and the results will be practically the same4 ,illustration3 ,fig4 #he4--,wiring ,diagram of ,short ,distance ,wireless ,telephone ,set4 7,microphone in ,aerial ,wire47 ,next connect one end of the grid condenser to the post of the tuning coil that makes connection with the microphone and the other end to the grid of the tube1 and then shunt the grid leak around the condenser4 ,connect the or positive electrode of the storage battery with one terminal of the filament of the vacuum tube1 the other terminal of the filament with one post of the rheostat and the other post of this with the - or negative electrode of the battery4 ,this done1 connect clip #b of the tuning coil to the or positive electrode of the battery and bring a lead from it to one of the switch taps of the panel cut-out4 ,now connect clip #c of the tuning coil with one end of the blocking condenser1 the other end of this with one terminal of the choke coil and the other terminal of the latter with the other switch tap of the cut-out4 ,connect the protective condenser across the direct current feed wires between the panel cut-out and the choke coil4 ,finally connect the ends of a lamp cord to the fuse socket taps of the cut-out1 and connect the other ends to a lamp plug and screw it into the lamp socket of the feed wires4 ,screw in a pair of #e ampere fuse plugs1 close the switch and you are ready to tune the transmitter and talk to your friends4 ,a #be to #ej ,mile ,wireless ,telephone ,transmitter--,with ,direct ,current ,motor ,generator4--,where you have to start with #aaj or #bbj volt direct current and you want to transmit to a distance of #be miles or more you will have to install a motor-generator4 ,to make this transmitter you will need exactly the same apparatus as that described and pictured for the #ajj ,mile ,c4 ,w4 ,telegraph ,transmitting ,set in ,chapter ,,xvi1 except that you must substitute a microphone transmitter and a telephone induction coil1 or a microphone transformer1 or still better1 a magnetic modulator1 for the telegraph key and chopper4 ,the ,apparatus ,you ,need4--,to reiterate2 the pieces of apparatus you need are3 7#a7 one aerial ammeter as shown at ,e in ,fig4 #ge2 7#b7 one tuning coil as shown at ,a in ,fig4 #gg2 7#c7 one aerial condenser as shown at ,b in ,fig4 #gg2 7#d7 one grid leak as shown at ,c in ,fig4 #gg2 7#e7 one grid1 blocking and protective condenser2 7#f7 one #e watt oscillator tube as shown at ,e in ,fig4 #gg2 7#g7 one rheostat as shown at ,i in ,fig4 #ge2 7#h7 one #aj volt 7#e cell7 storage battery2 7#i7 one choke coil2 7#aj7 one panel cut-out as shown at ,k in ,fig4 #ge1 and 7#aa7 a motor-generator having an input of #aaj or #bbj volts and an output of #cej volts4 ,in addition to the above apparatus you will need3 7#ab7 a microphone transmitter as shown in ,fig4 #hd2 7#ac7 a battery of four dry cells or a #f volt storage battery1 and either 7#ad7 a telephone induction coil as shown in ,fig4 #hf2 7#ae7 a microphone transformer as shown in ,fig4 #hg2 or a magnetic modulator as shown in ,fig4 #hh4 ,all of these parts have been described1 as said above1 in ,chapter ,,xvi1 except the microphone modulators4 ,illustration3 ,fig4 #hf4--,telephone ,induction ,coil4 7,used with ,microphone ,transmitter47 ,illustration3 ,fig4 #hg4--,microphone ,transformer4 7,used with ,microphone ,transmitter47 ,illustration3 ,fig4 #hh4--,magnetic ,modulator4 7,used with ,microphone ,transmitter47 ,the ,telephone ,induction ,coil4--,this is a little induction coil that transforms the #f-volt battery current after it has flowed through and been modulated by the microphone transmitter into alternating currents that have a potential of #a1jjj volts of more4 ,it consists of a primary coil of ,no4 #bj ,b4 and ,s4 gauge cotton covered magnet wire wound on a core of soft iron wires while around the primary coil is wound a secondary coil of ,no4 #cj magnet wire4 ,get a standard telephone induction coil that has a resistance of #ejj or #gej ohms and this will cost you a couple of dollars4 ,the ,microphone ,transformer4--,this device is built on exactly the same principle as the telephone induction coil just described but it is more effective because it is designed especially for modulating the oscillations set up by vacuum tube transmitters4 ,as with the telephone induction coil1 the microphone transmitter is connected in series with the primary coil and a #f volt dry or storage battery4 ,in the better makes of microphone transformer1 there is a third winding1 called a side tone coil1 to which a headphone can be connected so that the operator who is speaking into the microphone can listen-in and so learn if his transmitter is working up to standard4 ,the ,magnetic ,modulator4--,this is a small closed iron core transformer of peculiar design and having a primary and a secondary coil wound on it4 ,this device is used to control the variations of the oscillating currents that are set up by the oscillator tube4 ,it is made in three sizes and for the transmitter here described you want the smallest size1 which has an output of #a_/b to #a-a_/b amperes4 ,it costs about #aj4jj4 ,how the ,apparatus ,is ,connected ,up4--,the different pieces of apparatus are connected together in exactly the same way as the #ajj ,mile ,c4 ,w4 ,telegraph ,set in ,chapter ,,xvi except that the microphone transmitter and microphone modulator 7whichever kind you use7 is substituted for the telegraph key and chopper4 ,now there are three different ways that the microphone and its modulator can be connected in circuit4 ,two of the best ways are shown at ,a and ,b in ,fig4 #hi4 ,in the first way the secondary terminals of the modulator are shunted around the grid leak in the grid circuit as at ,a1 and in the second the secondary terminals are connected in the aerial as at ,b4 ,where an induction coil or a microphone transformer is used they are shunted around a condenser1 but this is not necessary with the magnetic modulator4 ,where a second tube is used as in ,fig4 #ij then the microphone and its modulator are connected with the grid circuit and clip #c of the tuning coil4 ,illustration3 ,fig4 #hi4--,wiring ,diagram of #be to #ej ,mile ,wireless ,telephone4 7,microphone ,modulator ,shunted ,around ,grid-,leak ,condenser47 ,illustration3 7,b7 ,fig4 #hi4--,microphone ,modulator ,connected in ,aerial ,wire4 ,illustration3 ,fig4 #ij4--,wiring ,diagram of #ej to #ajj ,mile ,wireless ,telephone ,transmitting ,set4 ,a #ej to #ajj ,mile ,wireless ,telephone ,transmitter--,with ,direct ,current ,motor ,generator4--,as the initial source of current available is taken to be a #aaj or #bbj volt direct current a motor-generator having an output of #cej volts must be used as before4 ,the only difference between this transmitter and the preceding one is that3 7#a7 two #e watt tubes are used1 the first serving as an oscillator and the second as a modulator2 7#b7 an oscillation choke coil is used in the plate circuit2 7#c7 a reactance coil or reactor1 is used in the plate circuit2 and 7#d7 a reactor is used in the grid circuit4 ,the ,oscillation ,choke ,coil4--,you can make this choke coil by winding about #bge turns of ,no4 #bh ,b4 and ,s4 gauge cotton covered magnet wire on a spool #b inches in diameter and #d inches long4 ,give it a good coat of shellac varnish and let it dry thoroughly4 ,the ,plate and ,grid ,circuit ,reactance ,coils4--,where a single tube is used as an oscillator and a second tube is employed as a modulator1 a reactor1 which is a coil of wire wound on an iron core1 is used in the plate circuit to keep the high voltage direct current of the motor-generator the same at all times4 ,likewise the grid circuit reactor is used to keep the voltage of the grid at a constant value4 ,these reactors are made alike and a picture of one of them is shown in ,fig4 #ia and each one will cost you #e4ge4 ,illustration3 ,fig4 #ia4--,plate and ,grid ,circuit ,reactor4 ,connecting up the ,apparatus4--,all of the different pieces of apparatus are connected up as shown in ,fig4 #hi4 ,one of the ends of the secondary of the induction coil1 or the microphone transformer1 or the magnetic modulator is connected to the grid circuit and the other end to clip #c of the tuning coil4 ,a #ajj to #bjj ,mile ,wireless ,telephone ,transmitter--,with ,direct ,current ,motor ,generator4--,by using the same connections shown in the wiring diagrams in ,fig4 #hi and a single #ej watt oscillator tube your transmitter will then have a range of #ajj miles or so1 while if you connect up the apparatus as shown in ,fig4 #ij and use two #ej watt tubes you can work up to #bjj miles4 ,much of the apparatus for a #ej watt oscillator set where either one or two tubes are used is of the same size and design as that just described for the #e watt oscillator sets1 but1 as in the ,c4 ,w4 telegraph sets1 some of the parts must be proportionately larger4 ,the required parts are 7#a7 the #ej watt tube2 7#b7 the grid leak resistance2 7#c7 the filament rheostat2 7#d7 the filament storage battery2 and 7#e7 the magnetic modulator4 ,all of these parts1 except the latter1 are described in detail under the heading of a #ejj ,mile ,c4 ,w4 ,telegraph ,transmitting ,set in ,chapter ,,xvi1 and are also pictured in that chapter4 ,it is not advisable to use an induction coil for the modulator for this set1 but use1 instead1 either a telephone transformer1 or better1 a magnetic modulator of the second size which has an output of from #a-a_/b to #c-a_/b amperes4 ,the magnetic modulator is described and pictured in this chapter4 ,a #ej to #ajj ,mile ,wireless ,telephone ,transmitting ,set--,with #aaj ,volt ,alternating ,current4--,if you have a #aaj volt ,footnote3 ,alternating current for lighting purposes ranges from #ajb4e volts to #aae volts1 so we take the median and call it #aaj volts4 alternating current available you can use it for the initial source of energy for your wireless telephone transmitter4 ,the chief difference between a wireless telephone transmitting set that uses an alternating current and one that uses a direct current is that3 7#a7 a power transformer is used for stepping up the voltage instead of a motor-generator1 and 7#b7 a vacuum tube rectifier must be used to convert the alternating current into direct current4 ,the ,apparatus ,you ,need4--,for this telephone transmitting set you need3 7#a7 one aerial ammeter2 7#b7 one tuning coil2 7#c7 one telephone modulator2 7#d7 one aerial series condenser2 7#e7 one #d cell dry battery or a #f volt storage battery2 7#f7 one microphone transmitter2 7#g7 one battery switch2 7#h7 one grid condenser2 7#i7 one grid leak2 7#aj7 two #e watt oscillator tubes with sockets2 7#aa7 one blocking condenser2 7#ab7 one oscillation choke coil2 7#ac7 two filter condensers2 7#ad7 one filter reactance coil2 7#ae7 an alternating current power transformer1 and 7#af7 two #bj watt rectifier vacuum tubes4 ,all of the above pieces of apparatus are the same as those described for the #ajj ,mile ,c4 ,w4 ,telegraph ,transmitter in ,chapter ,,xvii1 except3 7a7 the microphone modulator2 7b7 the microphone transmitter and 7c7 the dry or storage battery1 all of which are described in this chapter2 and the new parts which are3 7d7 the rectifier vacuum tubes2 7e7 the filter condensers2 and 7f7 the filter reactance coil2 further and finally1 the power transformer has a third secondary coil on it and it is this that feeds the alternating current to the rectifier tubes1 which in turn converts it into a pulsating direct current4 ,the ,vacuum ,tube ,rectifier4--,this rectifier has two electrodes1 that is1 it has a filament and a plate like the original vacuum tube detector1 ,the smallest size rectifier tube requires a plate potential of #eej volts which is developed by one of the secondary coils of the power transformer4 ,the filament terminal takes a current of #g4e volts and this is supplied by another secondary coil of the transformer4 ,this rectifier tube delivers a direct current of #bj watts at #cej volts4 ,it looks exactly like the #e watt oscillator tube which is pictured at ,e in ,fig4 #gg4 ,the price is #g4ej4 ,the ,filter ,condensers4--,these condensers are used in connection with the reactance coil to smooth out the pulsating direct current after it has passed through the rectifier tube4 ,they have a capacitance of #a mfd4 and will stand #gej volts4 ,these condensers cost about #b4jj each4 ,the ,filter ,reactance ,coil4--,this reactor which is shown in ,fig4 #ib1 has about the same appearance as the power transformer but it is somewhat smaller4 ,it consists of a coil of wire wound on a soft iron core and has a large inductance1 hence the capacitance of the filter condensers are proportionately smaller than where a small inductance is used which has been the general practice4 ,the size you require for this set has an output of #afj milliamperes and it will supply current for one to four #e watt oscillator tubes4 ,this size of reactor costs #aa4ej4 ,illustration3 ,fig4 #ib4--;,filter ,reactor for ,smoothing out ,rectified ,currents4 ,connecting ,up the ,apparatus4--,the wiring diagram in ,fig4 #ic shows how the various pieces of apparatus for this telephone transmitter are connected up4 ,you will observe3 7#a7 that the terminals of the power transformer secondary coil which develops #aj volts are connected to the filaments of the oscillator tubes2 7#b7 that the terminals of the other secondary coil which develops #aj volts are connected with the filaments of the rectifier tubes2 7#c7 that the terminals of the third secondary coil which develops #eej volts are connected with the plates of the rectifier tubes2 7#d7 that the pair of filter condensers are connected in parallel and these are connected to the mid-taps of the two filament secondary coils2 7#e7 that the reactance coil and the third filter condenser are connected together in series and these are shunted across the filter condensers1 which are in parallel2 and1 finally1 7#f7 a lead connects the mid-tap of the #eej-volt secondary coil of the power transformer with the connection between the reactor and the third filter condenser4 ,illustration3 ,fig #ic4--ajj to #bjj ,mile ,wireless ,telephone ,transmitter4 ,a #ajj to #bjj ,mile ,wireless ,telephone ,transmitting ,set--,with #aaj ,volt ,alternating ,current4--,this telephone transmitter is built up of exactly the same pieces of apparatus and connected up in precisely the same way as the one just described and shown in ,fig4 #ic4 ,apparatus ,required4--,the only differences between this and the preceding transmitter are3 7#a7 the magnetic modulator1 if you use one1 should have an output of #c-a_/b to #e amperes2 7#b7 you will need two #ej watt oscillator tubes with sockets2 7#c7 two #aej watt rectifier tubes with sockets2 7#d7 an aerial ammeter that reads to #e amperes2 7#e7 three #a mfd4 filter condensers in parallel2 7#f7 two filter condensers of #a mfd4 capacitance that will stand #agej volts2 and 7#f7 a #cjj milliampere filter reactor4 ,the apparatus is wired up as shown in ,fig4 #ic4 ,,chapter ,,xix ,,the ,,operation ,,of ,,vacuum ,,tube ,,transmitters ,the three foregoing chapters explained in detail the design and construction of 7#a7 two kinds of ,c4 ,w4 telegraph transmitters1 and 7#b7 two kinds of wireless telephone transmitters1 the difference between them being whether they used 7,a7 a direct current1 or 7,b7 an alternating current as the initial source of energy4 ,of course there are other differences between those of like types as1 for instance1 the apparatus and connections used 7a7 in the key circuits1 and 7b7 in the microphone circuits4 ,but in all of the transmitters described of whatever type or kind the same fundamental device is used for setting up sustained oscillations and this is the vacuum tube4 ,the ,operation of the ,vacuum ,tube ,oscillator4--,the operation of the vacuum tube in producing sustained oscillations depends on 7#a7 the action of the tube as a valve in setting up the oscillations in the first place and 7#b7 the action of the grid in amplifying the oscillations thus set up1 both of which we explained in ,chapter ,,xiv4 ,in that chapter it was also pointed out that a very small change in the grid potential causes a corresponding and larger change in the amount of current flowing from the plate to the filament2 and that if a vacuum tube is used for the production of oscillations the initial source of current must have a high voltage1 in fact the higher the plate voltage the more powerful will be the oscillations4 ,to understand how oscillations are set up by a vacuum tube when a direct current is applied to it1 take a look at the simple circuits shown in ,fig4 #id4 ,now when you close the switch the voltage from the battery charges the condenser and keeps it charged until you open it again2 the instant you do this the condenser discharges through the circuit which includes it and the inductance coil1 and the discharge of a condenser is always oscillatory4 ,illustration3 7,a7 and 7,b7 ,fig4 #id4 ,operation of ,vacuum ,tube ,oscillators4 ,where an oscillator tube is included in the circuits as shown at ,a and ,b in ,fig4 #id1 the grid takes the place of the switch and any slight change in the voltage of either the grid or the plate is sufficient to start a train of oscillations going4 ,as these oscillations surge through the tube the positive parts of them flow from the plate to the filament and these carry more of the direct current with them4 ,to make a tube set up powerful oscillations then1 it is only necessary that an oscillation circuit shall be provided which will feed part of the oscillations set up by the tube back to the grid circuit and when this is done the oscillations will keep on being amplified until the tube reaches the limit of its output4 ,illustration3 7,c7 ,fig4 #id4--;,how a ,direct ,current ,sets up ,oscillations4 ,the ,operation of ,c4 ,w4 ,telegraph ,transmitters ,with ,direct ,current--,short ,distance ,c4 ,w4 ,transmitter4--,in the transmitter shown in the wiring diagram in ,fig4 #gf the positive part of the #aaj volt direct current is carried down from the lamp socket through one side of the panel cut-out1 thence through the choke coil and to the plate of the oscillator tube1 when the latter is charged to the positive sign4 ,the negative part of the #aaj volt direct current then flows down the other wire to the filament so that there is a difference of potential between the plate and the filament of #aaj volts4 ,now when the #f-volt battery current is switched on the filament is heated to brilliancy1 and the electrons thrown off by it form a conducting path between it and the plate2 the #aaj volt current then flows from the latter to the former4 ,now follow the wiring from the plate over to the blocking condenser1 thence to clip #c of the tuning coil1 through the turns of the latter to clip #b and over to the filament and1 when the latter is heated1 you have a closed oscillation circuit4 ,the oscillations surging in the latter set up other and like oscillations in the tuning coil between the end of which is connected with the grid1 the aerial and the clip #b1 and these surge through the circuit formed by this portion of the coil1 the grid condenser and the filament2 this is the amplifying circuit and it corresponds to the regenerative circuit of a receiving set4 ,when oscillations are set up in it the grid is alternately charged to the positive and negative signs4 ,these reversals of voltage set up stronger and ever stronger oscillations in the plate circuit as before explained4 ,not only do the oscillations surge in the closed circuits but they run to and fro on the aerial wire when their energy is radiated in the form of electric waves4 ,the oscillations are varied by means of the telegraph key which is placed in the grid circuit as shown in ,fig4 #gf4 ,the ,operation of the ,key ,circuit4--,the effect in a ,c4 ,w4 transmitter when a telegraph key is connected in series with a buzzer and a battery and these are shunted around the condenser in the grid circuit1 is to rapidly change the wave form of the sustained oscillations1 and hence1 the length of the waves that are sent out4 ,while no sound can be heard in the headphones at the receiving station so long as the points of the key are not in contact1 when they are in contact the oscillations are modulated and sounds are heard in the headphones that correspond to the frequency of the buzzer in the key circuit4 ,the ,operation of ,c4 ,w4 ,telegraph ,transmitters with ,direct ,current4--,the chief differences between the long distance sets which use a direct current1 i4e41 those described in ,chapter ,,xvi1 and the short distance transmitting sets are that the former use3 7#a7 a motor-generator set for changing the low voltage direct current into high voltage direct current1 and 7#b7 a chopper in the key circuit4 ,the way the motor-generator changes the low- into high-voltage current has been explained in ,chapter ,,xvi4 ,the chopper interrupts the oscillations surging through the grid circuit at a frequency that the ear can hear1 that is to say1 about #hjj to #a1jjj times per second4 ,when the key is open1 of course1 the sustained oscillations set up in the circuits will send out continuous waves but when the key is closed these oscillations are broken up and then they send out discontinuous waves4 ,if a heterodyne receiving set1 see ,chapter ,,xv1 is being used at the other end you can dispense with the chopper and the key circuit needed is very much simplified4 ,the operation of key circuits of the latter kind will be described presently4 ,the ,operation of ,c4 ,w4 ,telegraph ,transmitters with ,alternating ,current--,with a ,single ,oscillator ,tube4--,where an oscillator tube telegraph transmitter is operated by a #aaj volt alternating current as the initial source of energy1 a buzzer1 chopper or other interruptor is not needed in the key circuit4 ,this is because oscillations are set up only when the plate is energized with the positive part of the alternating current and this produces an intermittent musical tone in the headphones4 ,hence this kind of a sending set is called a tone transmitter4 ,since oscillations are set up only by the positive part or voltage of an alternating current it is clear that1 as a matter of fact1 this kind of a transmitter does not send out continuous waves and therefore it is not a ,c4 ,w4 transmitter4 ,this is graphically shown by the curve of the wave form of the alternating current and the oscillations that are set up by the positive part of it in ,fig4 #ie4 ,whenever the positive half of the alternating current energizes the plate then oscillations are set up by the tube and1 conversely1 when the negative half of the current charges the plate no oscillations are produced4 ,illustration3 ,fig4 #ie4--,positive ,voltage only sets up ,oscillations4 ,you will also observe that the oscillations set up by the positive part of the current are not of constant amplitude but start at zero the instant the positive part begins to energize the plate and they keep on increasing in amplitude as the current rises in voltage until the latter reaches its maximum2 then as it gradually drops again to zero the oscillations decrease proportionately in amplitude with it4 ,heating the ,filament with ,alternating ,current4--,where an alternating current power transformer is used to develop the necessary plate voltage a second secondary coil is generally provided for heating the filament of the oscillation tube4 ,this is better than a direct current for it adds to the life of the filament4 ,when you use an alternating current to heat the filament keep it at the same voltage rather than at the same amperage 7current strength74 ,to do this you need only to use a voltmeter across the filament terminals instead of an ammeter in series with it2 then regulate the voltage of the filament with a rheostat4 ,the ,operation of ,c4 ,w4 ,telegraph ,transmitters with ,alternating ,current--,with ,two ,oscillator ,tubes4--,by using two oscillator tubes and connecting them up with the power transformer and oscillating circuits as shown in the wiring diagram in ,fig4 #hc the plates are positively energized alternately with every reversal of the current and1 consequently1 there is no time period between the ending of the oscillations set up by one tube and the beginning of the oscillations set up by the other tube4 ,in other words these oscillations are sustained but as in the case of those of a single tube1 their amplitude rises and falls4 ,this kind of a set is called a full wave rectification transmitter4 ,the waves radiated by this transmitter can be received by either a crystal detector or a plain vacuum-tube detector but the heterodyne receptor will give you better results than either of the foregoing types4 ,the ,operation of ,wireless ,telephone ,transmitters with ,direct ,current--,short ,distance ,transmitter4--,the operation of this short distance wireless telephone transmitter1 a wiring diagram of which is shown in ,fig4 #he is exactly the same as that of the ,direct ,current ,short ,distance ,c4 ,w4 ,telegraph ,transmitter already explained in this chapter4 ,the only difference in the operation of these sets is the substitution of the microphone transmitter for the telegraph key4 ,the ,microphone ,transmitter4--,the microphone transmitter that is used to vary1 or modulate1 the sustained oscillations set up by the oscillator tube and circuits is shown in ,fig4 #hd4 ,by referring to the diagram at ,a in this figure you will readily understand how it operates4 ,when you speak into the mouthpiece the sound waves1 which are waves in the air1 impinge upon the diaphragm and these set it into vibration--that is1 they make it move to and fro4 ,when the diaphragm moves toward the back of the transmitter it forces the carbon granules that are in the cup closer together2 this lowers their resistance and allows more current from the battery to flow through them2 when the pressure of the air waves is removed from the diaphragm it springs back toward the mouth-piece and the carbon granules loosen up when the resistance offered by them is increased and less current can flow through them4 ,where the oscillation current in the aerial wire is small the transmitter can be connected directly in series with the latter when the former will surge through it4 ,as you speak into the microphone transmitter its resistance is varied and the current strength of the oscillations is varied accordingly4 ,the ,operation of ,wireless ,telephone ,transmitters with ,direct ,current--,long ,distance ,transmitters4--,in the wireless telephone transmitters for long distance work which were shown and described in the preceding chapter a battery is used to energize the microphone transmitter1 and these two elements are connected in series with a microphone modulator4 ,this latter device may be either 7#a7 a telephone induction coil1 7#b7 a microphone transformer1 or 7#c7 a magnetic modulator2 the first two of these devices step-up the voltage of the battery current and the amplified voltage thus developed is impressed on the oscillations that surge through the closed oscillation circuit or the aerial wire system according to the place where you connect it4 ,the third device works on a different principle and this will be described a little farther along4 ,the ,operation of ,microphone ,modulators--,the ,induction ,coil4--,this device is really a miniature transformer1 see ,a in ,fig4 #hf1 and its purpose is to change the #f volt direct current that flows through the microphone into #ajj volts alternating current2 in turn1 this is impressed on the oscillations that are surging in either 7#a7 the grid circuit as shown at ,a in ,fig4 #hi1 and in ,fig4 #ij1 7#b7 the aerial wire system1 as shown at ,b in ,fig4 #hi and ,fig4 #ic4 ,when the current from the battery flows through the primary coil it magnetizes the soft iron core and as the microphone varies the strength of the current the high voltage alternating currents set up in the secondary coil of the induction coil are likewise varied1 when they are impressed upon and modulate the oscillating currents4 ,the ,microphone ,transformer4--,this is an induction coil that is designed especially for wireless telephone modulation4 ,the iron core of this transformer is also of the open magnetic circuit type1 see ,a in ,fig4 #hg1 and the ratio of the turns ,footnote3 ,see ,chapter ,,vi of the primary and the secondary coil is such that when the secondary current is impressed upon either the grid circuit or the aerial wire system it controls the oscillations flowing through it with the greatest efficiency4 ,the ,magnetic ,modulator4--,this piece of apparatus is also called a magnetic amplifier4 ,the iron core is formed of very thin plates1 or laminations as they are called1 and this permits high-frequency oscillations to surge in a coil wound on it4 ,in this transformer1 see ,a in ,fig4 #hh1 the current flowing through the microphone varies the magnetic permeability of the soft iron core by the magnetic saturation of the latter4 ,since the microphone current is absolutely distinct from the oscillating currents surging through the coil of the transformer a very small direct current flowing through a coil on the latter will vary or modulate very large oscillating currents surging through the former4 ,it is shown connected in the aerial wire system at ,a in ,fig4 #hh1 and in ,fig4 #ic4 ,operation of the ,vacuum ,tube as a ,modulator4--,where a microphone modulator of the induction coil or microphone transformer type is connected in the grid circuit or aerial wire system the modulation is not very effective1 but by using a second tube as a modulator1 as shown in ,fig4 #ij1 an efficient degree of modulation can be had4 ,now there are two methods by which a vacuum tube can be used as a modulator and these are3 7#a7 by the absorption of the energy of the current set up by the oscillator tube1 and 7#b7 by varying the direct current that energizes the plate of the oscillator tube4 ,the first of these two methods is not used because it absorbs the energy of the oscillating current produced by the tube and it is therefore wasteful4 ,the second method is an efficient one1 as the direct current is varied before it passes into the oscillator tube4 ,this is sufficient reason for describing only the second method4 ,the voltage of the grid of the modulator tube is varied by the secondary coil of the induction coil or microphone transformer1 above described4 ,in this way the modulator tube acts like a variable resistance but it amplifies the variations impressed on the oscillations set up by the oscillator tube4 ,as the magnetic modulator does the same thing a vacuum tube used as a modulator is not needed where the former is employed4 ,for this reason a magnetic modulator is the cheapest in the long run4 ,the ,operation of ,wireless ,telephone ,transmitters with ,alternating ,current4--,where an initial alternating current is used for wireless telephony1 the current must be rectified first and then smoothed out before passing into the oscillator tube to be converted into oscillations4 ,further so that the oscillations will be sustained1 two oscillator tubes must be used1 and1 finally1 in order that the oscillations may not vary in amplitude the alternating current must be first changed into direct current by a pair of rectifier vacuum tubes1 as shown in ,fig4 #ic4 ,when this is done the plates will be positively charged alternately with every reversal of the current in which case there will be no break in the continuity of the oscillations set up and therefore in the waves that are sent out4 ,the ,operation of ,rectifier ,vacuum ,tubes4--,the vacuum tube rectifier is simply a two electrode vacuum tube4 ,the way in which it changes a commercial alternating current into pulsating direct current is the same as that in which a two electrode vacuum tube detector changes an oscillating current into pulsating direct currents and this has been explained in detail under the heading of ,the ,operation of a ,two ,electrode ,vacuum ,tube ,detector in ,chapter ,,xii4 ,in the ,c4 ,w4 ,telegraph ,transmitting ,sets described in ,chapter ,,xvii1 the oscillator tubes act as rectifiers as well as oscillators but for wireless telephony the alternating current must be rectified first so that a continuous direct current will result4 ,the ,operation of ,reactors and ,condensers4--,a reactor is a single coil of wire wound on an iron core1 see ,fig4 #ij and ,a in ,fig4 #ia1 and it should preferably have a large inductance4 ,the reactor for the plate and grid circuit of a wireless telephone transmitter where one or more tubes are used as modulators as shown in the wiring diagram in ,fig4 #ij1 and the filter reactor shown in ,fig4 #ib1 operate in the same way4 ,when an alternating current flows through a coil of wire the reversals of the current set up a counter electromotive force in it which opposes1 that is reacts1 on the current1 and the higher the frequency of the current the greater will be the reactance4 ,when the positive half of an alternating current is made to flow through a large resistance the current is smoothed out but at the same time a large amount of its energy is used up in producing heat4 ,but when the positive half of an alternating current is made to flow through a large inductance it acts like a large resistance as before and likewise smooths out the current1 but none of its energy is wasted in heat and so a coil having a large inductance1 which is called an inductive reactance1 or just reactor for short1 is used to smooth out1 or filter1 the alternating current after it has been changed into a pulsating direct current by the rectifier tubes4 ,a condenser also has a reactance effect on an alternating current but different from an induction coil the lower the frequency the greater will be the reactance4 ,for this reason both a filter reactor and filter condensers are used to smooth out the pulsating direct currents4 ,,chapter ,,xx ,,how ,,to ,,make ,a ,,receiving ,,set ,,for #e4jj ,,or ,,less ,in the chapters on ,receptors you have been told how to build up high-grade sets4 ,but there are thousands of boys1 and1 probably1 not a few men1 who cannot afford to invest #be4jj1 more or less1 in a receiving set and would like to experiment in a small way4 ,the following set is inexpensive1 and with this cheap1 little portable receptor you can get the ,morse code from stations a hundred miles distant and messages and music from broadcasting stations if you do not live too far away from them4 ,all you need for this set are3 7#a7 a crystal detector1 7#b7 a tuning coil and 7#c7 an earphone4 ,you can make a crystal detector out of a couple of binding posts1 a bit of galena and a piece of brass wire1 or1 better1 you can buy one all ready to use for #ej cents4 ,illustration3 ,wireless ,receptor1 the size of a ,safety ,match ,box4 ,a ,youthful ,genius in the person of ,kenneth ,r4 ,hinman1 ,who is only twelve years old1 has made a ,wireless ,receiving ,set that fits neatly into a ,safety ,match ,box4 ,with this ,instrument and a ,pair of ,ordinary ,receivers1 ,he is able to catch not only ,code ,messages but the regular ,broadcasting ,programs from ,stations ,twenty and ,thirty ,miles ,distant4 ,the ,crystal ,detector4--,this is known as the ,rasco baby detector and it is made and sold by the ,radio ,specialty ,company1 #if ,park ,place1 ,new ,york ,city4 ,it is shown in ,fig4 #if4 ,the base is made of black composition and on it is mounted a standard in which a rod slides and on one end of this there is fixed a hard rubber adjusting knob while the other end carries a thin piece of phosphor-bronze wire1 called a cat-whisker4 ,to secure the galena crystal in the cup you simply unscrew the knurled cap1 place it in the cavity of the post and screw the cap back on again4 ,the free end of the cat-whisker wire is then adjusted so that it will rest lightly on the exposed part of the galena4 ,illustration3 ,fig4 #if4--,rasco ,baby ,crystal ,detector4 ,the ,tuning ,coil4--,you will have to make this tuning coil1 which you can do at a cost of less than #a4jj1 as the cheapest tuning coil you can buy costs at least #c4jj1 and we need the rest of our #e4jj to invest in the earphone4 ,get a cardboard tube1 such as is used for mailing purposes1 #b inches in diameter and #c inches long1 see ,a in ,fig4 #ig4 ,now wind on #bej turns of ,no4 #dj ,brown and ,sharpe gauge plain enameled magnet wire4 ,you can use ,no4 #dj double cotton covered magnet wire1 in which case you will have to shellac the tube and the wire after you get it on4 ,illustration3 ,fig4 #ig4--;,how the ,tuning ,coil is ,made4 ,as you wind on the wire take off a tap at every #aeth turn1 that is1 scrape the wire and solder on a piece about #g inches long1 as shown in ,fig4 #ii2 and do this until you have #f taps taken off4 ,instead of leaving the wires outside of the tube bring them to the inside of it and then out through one of the open ends4 ,now buy a round wood-base switch with #g contact points on it as shown at ,b in ,fig4 #ig4 ,this will cost you #be or #ej cents4 ,the ,headphone4--,an ordinary ,bell telephone receiver is of small use for wireless work as it is wound to too low a resistance and the diaphragm is much too thick4 ,if you happen to have a ,bell phone you can rewind it with ,no4 #dj single covered silk magnet wire1 or enameled wire of the same size1 when its sensitivity will be very greatly improved4 ,then you must get a thin diaphragm and this should not be enameled1 as this tends to dampen the vibrations of it4 ,you can get a diaphragm of the right kind for #e cents4 ,the better way1 though1 is to buy an earphone made especially for wireless work4 ,you can get one wound to #ajjj ohms resistance for #a4ge and this price includes a cord4 ,footnote3 ,this is ,mesco1 ,no4 #dgj wireless phone4 ,sold by the ,manhattan ,electrical ,supply ,co41 ,park ,place1 ,n4,y4,c4 ,for #a4jj extra you can get a head-band for it1 and then your phone will look like the one pictured in ,fig4 #ih4 ,illustration3 ,fig4 #ih4--,mesco #ajjj ,ohm ,head ,set4 ,how to ,mount the ,parts4--,now mount the coil on a wood base1 #a_/b or #a inch thick1 #c-a_/b inches wide and #e-a_/b inches long1 and then connect one end of the coil to one of the end points on the switch1 and connect each succeeding tap to one of the switch points1 as shown schematically in ,fig4 #ii and diagrammatically in ,fig4 #ajj4 ,this done1 screw the switch down to the base4 ,finally screw the detector to the base and screw two binding posts in front of the coil4 ,these are for the earphone4 ,illustration3 ,fig4 #ii4--,schematic ,layout of #e4jj ,receiving ,set4 ,illustration3 ,fig4 #ajj4--,wiring ,diagram for #e4jj ,receiving ,set4 ,the ,condenser4--,you do not have to connect a condenser across the earphone but if you do you will improve the receiving qualities of the receptor4 ,how to ,connect ,up the ,receptor4--,now connect up all the parts as shown in ,figs4 #ii and #ajj1 then connect the leading-in wire of the aerial with the lever of the switch2 and connect the free end of the tuning coil with the ground4 ,if you have no aerial wire try hooking it up to a rain pipe that is not grounded or the steel frame of an umbrella4 ,for a ground you can use a water pipe1 an iron pipe driven into the ground1 or a hydrant4 ,put on your headphone1 adjust the detector and move the lever over the switch contacts until it is in adjustment and then1 if all your connections are properly made1 you should be able to pick up messages4 ,illustration3 ,wireless ,set made into a ,ring1 designed by ,alfred ,g4 ,rinehart1 of ,elizabeth1 ,new ,jersey4 ,this little ,receptor is a ,practical ,set2 it will receive ,messages1 ,concerts1 etc41 ,measures #a by #e_/h by #g_/h4 ,an ordinary ,umbrella is used as an ,aerial4 ,,appendix ,,useful ,,information ,,abbreviations ,,of ,,units ,unit ,abbreviation ampere amp4 ampere-hours amp4-hr4 centimeter cm4 centimeter-gram-second c4g4s4 cubic centimeters cm4#c cubic inches cu4 in4 cycles per second degrees ,centigrade ,c4 degrees ,fahrenheit ,f4 feet ft4 foot-pounds ft4-lb4 grams g4 henries h4 inches in4 kilograms kg4 kilometers km4 kilowatts kw4 kilowatt-hours kw4-hr4 kilovolt-amperes kv4-a4 meters m4 microfarads ,greek3 muf4 micromicrofarads ,greek3 mu muf4 millihenries mh4 millimeters mm4 pounds lb4 seconds sec4 square centimeters cm4#b square inches sq4 in4 volts v4 watts w4 ,,prefixes ,,used ,,with ,,metric ,,system ,,units ,prefix ,abbreviation ,meaning micro ,greek3 mu4 #a millionth milli m4 #a thousandth centi c4 #a hundredth deci d4 #a tenth deka dk4 #aj hekto h4 #a hundred kilo k4 #a thousand mega m4 #a million ,,symbols ,,used ,,for ,,various ,,quantities ,quantity ,symbol capacitance ,c conductance g coupling co-efficient k current1 instantaneous i current1 effective value ,i decrement ,greek3 delta dielectric constant ,greek3 alpha electric field intensity ,greek3 epsilon electromotive force1 instantaneous value ,e electromotive force1 effective value ,f energy ,w force ,f frequency f frequency x #b;,greek3 pi ,greek3 omega impedance ,z inductance1 self ,l inductance1 mutual ,m magnetic field intensity ,a magnetic flux ,greek3 ,phi magnetic induction ,b period of a complete oscillation ,t potential difference ,v quantity of electricity ,q ratio of the circumference of a circle to its diameter #c4adaf ,greek3 pi reactance ,x resistance ,r time t velocity v velocity of light c wave length ,greek3 lambda wave length in meters ,greek3 lambdam work ,w permeability ,greek3 mu ,square root ,math3 square root ,,table ,,of ,,enameled ,,wire ,no4 of ,turns ,turns ,ohms per ,wire1 per per ,cubic ,inch ,b4 ,s4 ,linear ,square of ,gauge ,inch ,inch ,winding #bj #cj #hhe 4#gdh #bb #cg #adjj #a4hh #bd #df #bafj #d4fa #bf #eh #cdfj #aa4hj #bh #gc #edjj #bi4bj #cj #ia #hbfj #gj4ij #cb #aaf #ba1jjj #gedg4jj #cd #ade #ac1dcj #bifh4jj #cf #agh #ca1hbj #ajih4jj #ch #bcb #ed1jhj #def4jj #dj #bid #hf1ejj #ahc4jj ,,table ,,of ,,frequency ,,and ,,wave ,,lengths ,w4 ,l4--,wave ,lengths in ,meters4 ,f4--,number of ,oscillations per ,second4 ,o4 or square root ,l4 ,c4 is called ,oscillation ,constant4 ,c4--,capacity in ,microfarads4 ,l4--,inductance in ,centimeters4 #ajjj ,centimeters #a ,microhenry4 ,w4,l4 ,f ,o ,l4,c4 #ej #f1jjj1jjj 4#hci 4#gjci #ajj #c1jjj1jjj #a4fh #b4hb #aej #b1jjj1jjj #b4eb #f4ce #bjj #a1ejj1jjj #c4cf #aa4bi #bej #a1bjj1jjj #d4ai #ag4ee #cjj #a1jjj1jjj #e4je #be4cj #cej #heg1ajj #e4hg #cd4df #djj #gej1jjj #f4ga #de4jc #dej #fff1gjj #g4ee #eg4jj #ejj #fjj1jjj #h4ci #gj4ci #eej #ede1djj #i4bc #he4ai #fjj #ejj1jjj #aj4jg #aja4da #gjj #dbh1fjj #aa4gd #acg4hc #hjj #cge1jjj #ac4db #ahj4aj #ijj #ccc1cjj #ae4aj #bbh4ja #a1jjj #cjj1jjj #af4gh #bha4eg #a1ajj #bgb1gcj #ah4de #cdj4dj #a1bjj #bej1jjj #bj4ac #dje4bj #a1cjj #bcj1gfj #ba4ha #dge4gj #a1djj #bad1chj #bc4di #eea4hj #a1ejj #bjj1jjj #be4ag #fcc4ej #a1fjj #ahg1ejj #bf4hd #gbj4dj #a1gjj #agf1dfj #bh4eb #hac4dj #a1hjj #aff1fgj #cj4bj #iab4jj #a1ijj #aeg1hjj #ca4hh #a1jaf4dj #b1jjj #aej1jjj #cc4ee #a1abe4fj #b1ajj #adb1hej #ce4bc #a1bda4bj #b1bjj #acf1cfj #cf4ia #a1cfb4dj #b1cjj #acj1dcj #ch4ei #a1dhi4cj #b1djj #abe1jjj #dj4bg #a1fba4hj #b1ejj #abj1jjj #da4ie #a1gei4gj #b1fjj #aae1chj #dc4fb #a1ijb4fj #b1gjj #aaa1aaj #de4cj #b1jeb4jj #b1hjj #ajg1adj #df4hi #b1bjg4jj #b1ijj #ajc1dej #dh4ff #b1cff4cj #c1jjj #ajj1jjj #ej4cc #b1ecc4bj #d1jjj #ge1jjj #fg4aa #d1ejd4jj #e1jjj #fj1jjj #hc4hi #g1jch4jj #f1jjj #ej1jjj #ajj4g #aj1acj4jj #g1jjj #da1hjj #aag4c #ac1fcj4jj #h1jjj #cg1ejj #acd4a #ah1jjj4jj #i1jjj #cc1cjj #aea4j #bb1hbj4jj #aj1jjj #cj1jjj #afg4i #bh1aej4jj #aa1jjj #bg1cjj #ahd4h #cd1aej4jj #ab1jjj #be1jjj #bja4e #dj1fjj4jj #ac1jjj #bc1ajj #bah4c #dg1fjj4jj #ad1jjj #ba1djj #bce4j #ee1bjj4jj #ae1jjj #bj1jjj #beb4j #fc1ejj4jj #af1jjj #ah1gej #bfi4j #gb1cjj4jj ,,pronunciation ,,of ,,greek ,,letters ,many of the physical quantities use ,greek letters for symbols4 ,the following is the ,greek alphabet with the way the letters are pronounced3 a alpha b beta g gamma d delta e epsilon z zeta ae eta th theta i iota k kappa l lambda m mu n nu x ,xi7,zi7 o omicron p pi r rho s sigma t tau u upsilon ph phi ch chi ps psi o omega ,,table ,,of ,,sparking ,,distances ,in ,air for ,various ,voltages between ,needle ,points ,volts ,distance ,inches ,centimeter #e1jjj 4#bbe 4#eg #aj1jjj 4#dgj #a4ai #ae1jjj 4#gbe #a4hd #bj1jjj #a4jjj #b4ed #be1jjj #a4cjj #c4cj #cj1jjj #a4fbe #d4aj #ce1jjj #b4jjj #e4aj #dj1jjj #b4dej #f4bj #de1jjj #b4ie #g4ej #ej1jjj #c4ee #i4ij #fj1jjj #d4fe #aa4h #gj1jjj #e4he #ad4i #hj1jjj #g4aj #ah4j #ij1jjj #h4ce #ba4b #ajj1jjj #i4fj #bd4d #aaj1jjj #aj4ge #bg4c #abj1jjj #aa4he #cj4a #acj1jjj #ab4ie #cb4i #adj1jjj #ac4ie #ce4d #aej1jjj #ae4jj #ch4a ,,feet ,,per ,,pound ,,of ,,insulated ,,magnet ,,wire ,no4 of ,single ,double ,single ,double ,b4 ,s4 ,cotton1 ,cotton1 ,silk1 ,silk1 ,enamel ,gauge #d-,mils #h-,mils #a-c_/d-,mils #d-,mils #bj #caa #bih #cai #cab #cbj #ba #chi #cgj #djh #chi #djd #bb #dhh #dfa #ejc #dih #eji #bc #fab #ehd #fcf #fca #fdb #bd #gfb #gde #hjj #ggi #haj #be #ieg #ijc #a1jje #iff #a1jai #bf #a1aib #a1aah #a1bfe #a1bjb #a1bhf #bg #a1dhh #a1dbb #a1eij #a1edc #a1fbj #bh #a1heb #a1gei #a1igb #a1iag #b1jdb #bi #b1cge #b1bjg #b1egj #b1dce #b1egj #cj #b1hfj #b1ecd #c1ade #b1ijj #c1bdj #ca #c1hjj #b1gfh #c1idc #c1fhc #d1jhb #cb #d1cge #c1gcg #d1iej #d1fed #e1acb #cc #e1eij #d1fig #f1ahj #e1fhi #f1dde #cd #f1ejj #f1afh #g1gdj #g1aaa #h1jic #ce #h1jej #f1gcg #i1fjj #h1ehd #aj1aig #cf #i1hbj #g1hgg #ab1jjj #aj1jci #ab1hac #cg #aa1hfj #i1cji #ae1jjj #aj1fff #af1aaj #ch #ad1cjj #aj1fcf #ah1ffj #ad1bbb #bj1bgd #ci #ag1acj #aa1ijg #bc1aej #af1eaf #be1eai #dj #ba1eij #ad1bbb #bh1gjj #ba1ccc #cb1ajg ,,international ,,morse ,,code ,,and ,,conventional ,,signals ,,to ,,be ,,used ,,for ,,all ,,general ,,public ,,service ,,radio ,,communication #a4 ,a dash is equal to three dots4 #b4 ,the space between parts of the same letter is equal to one dot4 #c4 ,the space between two letters is equal to three dots4 #d4 ,the space between two words is equal to five dots4 ,note3 period denotes ,morse dot1 hyphen denotes ,morse dash ,a 4- ,b -444 ,c -4-4 ,d -44 ,e 4 ,f 44-4 ,g --4 ,h 4444 ,i 44 ,j 4--- ,k -4- ,l 4-44 ,m -- ,n -4 ,o --- ,p 4--4 ,q --4- ,r 4-4 ,s 444 ,t - ,u 44- ,v 444- ,w 4-- ,x -44- ,y -4-- ,z --44 7,german7 4-4- or 7,spanish-,scandinavian7 4--4- ,,ch 7,german-,spanish7 ---- 7,french7 44-44 7,spanish7 --4-- 7,german7 ---4 7,german7 44-- #a 4---- #b 44--- #c 444-- #d 4444- #e 44444 #f -4444 #g --444 #h ---44 #i ----4 #j ----- ,period 44 44 44 ,semicolon -4-4-4 ,comma -4-4-4 ,colon ---444 ,interrogation 44--44 ,exclamation point --44-- ,apostrophe 4----4 ,hyphen -4444- ,bar indicating fraction -44-4 ,parenthesis -4--4- ,inverted commas 4-44-4 ,underline 44--4- ,double dash -444- ,distress ,call 444---444 ,attention call to precede every transmission -4-4- ,general inquiry call -4-4 --4- ,from 7de7 -44 4 ,invitation to transmit 7go ahead7 -4- ,warning--high power --44-- ,question 7please repeat after 4447--interrupting long messages 44--44 ,wait 4-444 ,break 7,bk47 7double dash7 -444- ,understand 444-4 ,error 44444444 ,received 7,o4,k47 4-4 ,position report 7to precede all position messages7 - 4-4 ,end of each message 7cross7 4-4-4 ,transmission finished 7end of work7 7conclusion of correspondence7 444-4- ,,international ,,radiotelegraphic ,,convention ,,list ,,of ,,abbreviations ,,to ,,be ,,used ,,in ,,radio ,,communication ,,abbreviation ,,question ,,answer ,,or ,,reply ,,prb ,do you wish to communicate ,i wish to communicate by means by means of the ,international of the ,international ,signal ,code4 ,signal ,code8 ,,qra ,what ship or coast station is ,this is4444 that8 ,,qrb ,what is your distance8 ,my distance is4444 ,,qrc ,what is your true bearing8 ,my true bearing is4444 ,,qrd ,where are you bound for8 ,i am bound for4444 ,,qrf ,where are you bound from8 ,i am bound from4444 ,,qrg ,what line do you belong to8 ,i belong to the 444 ,line4 ,,qrh ,what is your wave length in ,my wave length is 444 meters4 meters8 ,,qrj ,how many words have you to send8 ,i have 444 words to send4 ,,qrk ,how do you receive me8 ,i am receiving well4 ,,qrl ,are you receiving badly8 ,i am receiving badly4 ,please ,shall ,i send #bj8 send #bj4 444-4 444-4 for adjustment8 for adjustment4 ,,qrm ,are you being interfered with8 ,i am being interfered with4 ,,qrn ,are the atmospherics strong8 ,atmospherics are very strong4 ,,qro ,shall ,i increase power8 ,increase power4 ,,qrp ,shall ,i decrease power8 ,decrease power4 ,,qrq ,shall ,i send faster8 ,send faster4 ,,qrs ,shall ,i send slower8 ,send slower4 ,,qrt ,shall ,i stop sending8 ,stop sending4 ,,qru ,have you anything for me8 ,i have nothing for you4 ,,qrv ,are you ready8 ,i am ready4 ,all right now4 ,,qrw ,are you busy8 ,i am busy 7or3 ,i am busy with44474 ,please do not interfere4 ,,qrx ,shall ,i stand by8 ,stand by4 ,i will call you when required4 ,,qry ,when will be my turn8 ,your turn will be ,no4444 ,,qrz ,are my signals weak8 ,you signals are weak4 ,,qsa ,are my signals strong8 ,you signals are strong4 ,,qsb ,is my tone bad8 ,the tone is bad4 ,is my spark bad8 ,the spark is bad4 ,,qsc ,is my spacing bad8 ,your spacing is bad4 ,,qsd ,what is your time8 ,my time is4444 ,,qsf ,is transmission to be in ,transmission will be in alternate order or in series8 alternate order4 ,,qsg ,transmission will be in a series of #e messages4 ,,qsh ,transmission will be in a series of #aj messages4 ,,qsj ,what rate shall ,i collect for4448 ,collect4444 ,,qsk ,is the last radiogram canceled8 ,the last radiogram is canceled4 ,,qsl ,did you get my receipt8 ,please acknowledge4 ,,qsm ,what is your true course8 ,my true course is444degrees4 ,,qsn ,are you in communication with land8 ,i am not in communication with land4 ,,qso ,are you in communication with ,i am in communication with444 any ship or station 7through44474 7or3 with44478 ,,qsp ,shall ,i inform444that you are ,inform444that ,i am calling him4 calling him8 ,,qsq ,is444calling me8 ,you are being called by4444 ,,qsr ,will you forward the radiogram8 ,i will forward the radiogram4 ,,qst ,have you received the general ,general call to all stations4 call8 ,,qsu ,please call me when you have ,will call when ,i have finished4 finished 7or3 at444o'clock78 ,,qsv ,is public correspondence being ,public correspondence is being handled8 handled4 ,please do not interfere4 ,footnote3 ,public correspondence is any radio work1 official or private1 handled on commercial wave lengths4 ,,qsw ,shall ,i increase my spark ,increase your spark frequency4 frequency8 ,,qsx ,shall ,i decrease my spark ,decrease your spark frequency4 frequency8 ,,qsy ,shall ,i send on a wavelength ,let us change to the wave length of 444 meters8 of 444 meters4 ,,qsz ,send each word twice4 ,i have difficulty in receiving you4 ,,qta ,repeat the last radiogram4 ,when an abbreviation is followed by a mark of interrogation1 it refers to the question indicated for that abbreviation4 ,useful ,information ,symbols ,used ,for ,apparatus alternator ammeter aerial arc battery buzzer condenser variable condenser connection of wires no connection coupled coils variable coupling detector gap1 plain gap1 quenched ground hot wire ammeter inductor variable inductor key resistor variable resistor switch s4p4s4t4 s4p4d4t4 d4p4s4t4 d4p4d4t4 reversing phone receiver transmitter thermoelement transformer vacuum tube voltmeter choke coil ,,definitions ,,of ,,electric ,,and ,,magnetic ,,units ,the ohm is the resistance of a thread of mercury at the temperature of melting ice1 #ad4deba grams in mass1 of uniform cross-section and a length of #ajf4cjj centimeters4 ,the ampere is the current which when passed through a solution of nitrate of silver in water according to certain specifications1 deposits silver at the rate of #j4jjaaahjj of a gram per second4 ,the volt is the electromotive force which produces a current of #a ampere when steadily applied to a conductor the resistance of which is #a ohm4 ,the coulomb is the quantity of electricity transferred by a current of #a ampere in #a second4 ,the ampere-hour is the quantity of electricity transferred by a current of #a ampere in #a hour and is1 therefore1 equal to #cfjj coulombs4 ,the farad is the capacitance of a condenser in which a potential difference of #a volt causes it to have a charge of #a coulomb of electricity4 ,the henry is the inductance in a circuit in which the electromotive force induced is #a volt when the inducing current varies at the rate of #a ampere per second4 ,the watt is the power spent by a current of #a ampere in a resistance of #a ohm4 ,the joule is the energy spent in ,i second by a flow of #a ampere in #a ohm4 ,the horse-power is used in rating steam machinery4 ,it is equal to #gdf watts4 ,the kilowatt is #a1jjj watts4 ,the units of capacitance actually used in wireless work are the microfarad1 which is the millionth part of a farad1 because the farad is too large a unit2 and the ,c4 ,g4 ,s4 electrostatic unit of capacitance1 which is often called the centimeter of capacitance1 which is about equal to #a4aa microfarads4 ,the units of inductance commonly used in radio work are the millihenry1 which is the thousandth part of a henry2 and the centimeter of inductance1 which is one one-thousandth part of a microhenry4 ,note4--,for further information about electric and magnetic units get the ,bureau of ,standards ,circular ,no4 #fj1 called ,electric ,units and ,standards1 the price of which is #ae cents2 also get ,scientific ,paper ,no4 #bib1 called ,international ,system of ,electric and ,magnetic ,units1 price #aj cents4 ,these and other informative papers can be had from the ,superintendent of ,documents1 ,government ,printing ,office1 ,washington1 ,d4 ,c4 ,,wireless ,,books ,the ,admiralty ,manual of ,wireless ,telegraphy4 #aibj4 ,published by ,his ,majesty's ,stationery ,office1 ,london4 ,ralph ,e4 ,batcher4--,prepared ,radio ,measurements4 #aiba4 ,wireless ,press1 ,inc41 ,new ,york ,city4 ,elmer ,e4 ,bucher4--,practical ,wireless ,telegraphy4 #aiah4 ,wireless ,press1 ,inc41 ,new ,york ,city4 ,elmer ,e4 ,bucher4--,vacuum ,tubes in ,wireless ,communication4 #aiai4 ,wireless ,press1 ,inc41 ,new ,york ,city4 ,elmer ,e4 ,bucher4--,the ,wireless ,experimenter's ,manual4 #aibj4 ,wireless ,press1 ,inc41 ,new ,york ,city4 ,a4 ,frederick ,collins4--,wireless ,telegraphy1 ,its ,history1 ,theory1 and ,practice4 #aije4 ,mc,graw ,pub4 ,co41 ,new ,york ,city4 ,j4 ,h4 ,dellinger4--,principles ,underlying ,radio ,communication4 #aiba4 ,signal ,corps1 ,u4 ,s4 ,army1 ,washington1 ,d4 ,c4 ,h4 ,m4 ,dorsett4--,wireless ,telegraphy and ,telephony4 #aibj4 ,wireless ,press1 ,ltd41 ,london4 ,j4 ,a4 ,fleming4--,principles of ,electric ,wave ,telegraphy4 #aiai4 ,longmans1 ,green and ,co41 ,london4 ,charles ,b4 ,hayward4--,how to ,become a ,wireless ,operator4 #aiah4 ,american ,technical ,society1 ,chicago1 ,ill4 ,g4 ,d4 ,robinson4--,manual of ,radio ,telegraphy and ,telephony4 #aibj4 ,united ,states ,naval ,institute1 ,annapolis1 ,md4 ,rupert ,stanley4--,textbook of ,wireless ,telegraphy4 #aiai4 ,longmans1 ,green and ,co41 ,london4 ,e4 ,w4 ,stone4--,elements of ,radio ,telegraphy4 #aiai4 ,d1 ,van ,nostrand ,co41 ,new ,york ,city4 ,l4 ,b4 ,turner4--,wireless ,telegraphy and ,telephony4 #aiba4 ,cambridge ,university ,press4 ,cambridge1 ,england4 ,send to the ,superintendent of ,documents1 ,government ,printing ,office1 ,washington1 ,d4 ,c41 for a copy of ,price ,list ,no4 #fd which lists the ,government's books and pamphlets on wireless4 ,it will be sent to you free of charge4 ,the ,government publishes2 7#a7 ,a ,list of ,commercial ,government and ,special ,wireless ,stations1 every year1 price #ae cents2 7#b7 ,a ,list of ,amateur ,wireless ,stations1 yearly1 price #ae cents2 7#c7 ,a ,wireless ,service ,bulletin is published monthly1 price #e cents a copy1 or #be cents yearly2 and 7#d7 ,wireless ,communication ,laws of the ,united ,states1 the ,international ,wireless ,telegraphic ,convention and ,regulations ,governing ,wireless ,operators and the ,use of ,wireless on ,ships and ,land ,stations1 price #ae cents a copy4 ,orders for the above publications should be addressed to the ,superintendent of ,documents1 ,government ,printing ,office1 ,washington1 ,d4 ,c4 ,manufacturers and ,dealers in ,wireless ,apparatus and ,supplies3 ,adams-,morgan ,co41 ,upper ,montclair1 ,n4 ,j4 ,american ,hard ,rubber ,co41 #aa ,mercer ,street1 ,new ,york ,city4 ,american ,radio and ,research ,corporation1 ,medford ,hillside1 ,mass4 ,brach 7,l4 ,s47 ,mfg4 ,co41 #abg ,sussex ,ave41 ,newark1 ,n4 ,j4 ,brandes 7,c47 ,inc41 #bcg ,lafayette ,st41 ,new ,york ,city4 ,bunnell 7,j4 ,h47 ,company1 ,park ,place1 ,new ,york ,city4 ,burgess ,battery ,company1 ,harris ,trust ,co4 ,bldg41 ,chicago1 ,ill4 ,clapp-,eastman ,co41 #abj ,main ,st41 ,cambridge1 ,mass4 ,connecticut ,telephone and ,telegraph ,co41 ,meriden1 ,conn4 ,continental ,fiber ,co41 ,newark1 ,del4 ,coto-,coil ,co41 ,providence1 ,r4 ,i4 ,crosley ,mfg4 ,co41 ,cincinnati1 ,ohio4 ,doolittle 7,f4 ,m471 #hag ,chapel ,st41 ,new ,haven1 ,conn4 ,edelman 7,philip ,e471 #i ,cortlandt ,st41 ,new ,york ,city4 ,edison ,storage ,battery ,co41 ,orange1 ,n4 ,j4 ,electric ,specialty ,co41 ,stamford1 ,conn4 ,electrose ,mfg4 ,co41 #fj ,washington ,st41 ,brooklyn1 ,n4 ,y4 ,general ,electric ,co41 ,schenectady1 ,n4 ,y4 ,grebe 7,a4 ,h47 and ,co41 ,inc41 ,richmond ,hill1 ,n4 ,y4 ,c4 ,international ,brass and ,electric ,co41 #agf ,beekman ,st41 ,new ,york ,city4 ,international ,insulating ,co41 #be ,west #deth ,st41 ,new ,york ,city4 ,king ,amplitone ,co41 #hb ,church ,st41 ,new ,york ,city4 ,kennedy 7,colin ,b47 ,co41 ,rialto ,bldg41 ,san ,francisco1 ,cal4 ,magnavox ,co41 ,oakland1 ,cal4 ,manhattan ,electrical ,supply ,co41 ,park ,place1 ,n4 ,y4 ,marshall-,gerken ,co41 ,toledo1 ,ohio4 ,michigan ,paper ,tube and ,can ,co41 #becf ,grand ,river ,ave41 ,detroit1 ,mich4 ,murdock 7,wm4 ,j47 ,co41 ,chelsea1 ,mass4 ,national ,carbon ,co41 ,inc41 ,long ,island ,city1 ,n4 ,y4 ,pittsburgh ,radio and ,appliance ,co41 #aab ,diamond ,st41 ,pittsburgh1 ,pa1 ,radio ,corporation of ,america1 #bcc ,broadway1 ,new ,york ,city4 ,riley-,klotz ,mfg4 ,co41 #ag-ai ,mulberry ,st41 ,newark1 ,n4 ,j4 ,radio ,specialty ,co41 #if ,park ,place1 ,new ,york ,city4 ,roller-,smith ,co41 #ae ,barclay ,st41 ,new ,york ,city4 ,tuska 7,c4 ,d47 ,co41 ,hartford1 ,conn4 ,western ,electric ,co41 ,chicago1 ,ill4 ,westinghouse ,electric ,co41 ,pittsburgh1 ,pa4 ,weston ,electrical ,instrument ,co41 #agc ,weston ,ave41 ,newark1 ,n4 ,j4 ,westfield ,machine ,co41 ,westfield1 ,mass4 ,,abbreviations ,,of ,,common ,,terms ,a4 44444444444444,aerial ,a4,c4 444444444444,alternating ,current ,a4,f4 444444444444,audio ,frequency ,b4 and ,s4 4444444,brown ,sharpe ,wire ,gauge ,c4 44444444444444,capacity or ,capacitance ,c4,g4,s4 4444444444,centimeter-,grain-,second ,cond4 44444444444,condenser ,coup4 44444444444,coupler ,c4,w4 444444444444,continuous ,waves ,d4,c4 444444444444,direct ,current ,d4,p4,d4,t4 44444444,double ,point ,double ,throw ,d4,p4,s4,t4 44444444,double ,point ,single ,throw ,d4,x4 444444444444,distance ,e4 44444444444444,short for ,electromotive ,force 7,volt7 ,e4,m4,f4 4444444444,electromotive ,force ,f4 44444444444444,filament or ,frequency ,g4 44444444444444,grid ,gnd4 444444444444,ground ,i4 44444444444444,current ,strength 7,ampere7 ,i4,c4,w4 4444444444,interrupted ,continuous ,waves ,,kw4 4444444444444,kilowatt ,l4 44444444444444,inductance ,l4,c4 444444444444,loose ,coupler ,litz4 44444444444,litzendraht ,mfd4 444444444444,microfarad ,neg4 444444444444,negative ,o4,t4 444444444444,oscillation ,transformer ,p4 44444444444444,plate ,prim4 44444444444,primary ,pos4 444444444444,positive ,r4 44444444444444,resistance ,r4,f4 444444444444,radio ,frequency ,sec4 444444444444,secondary ,s4,p4,d4,t4 44444444,single ,point ,double ,throw ,s4,p4,s4,t4 44444444,single ,point ,single ,throw ,s4,r4 444444444444,self ,rectifying ,t4 44444444444444,telephone or ,period 7time7 of ,complete ,oscillation ,tick4 44444444444,tickler ,v4 44444444444444,potential ,difference ,var4 444444444444,variometer ,var4 ,cond4 444444,variable ,condenser ,v4,t4 444444444444,vacuum ,tube ,w4,l4 444444444444,wave ,length ,x4 44444444444444,reactance ,,glossary ,a ,,battery4--,see ,battery ,a4 ,,abbreviations1 ,,code4--,abbreviations of questions and answers used in wireless communication4 ,the abbreviation of a question is usually in three letters of which the first is ,q4 ,thus ,q ,r ,b is the code abbreviation of what is your distance8 and the answer ,my distance is444 ,see ,page #cjf ,appendix3 ,list of ,abbreviations4 ,,abbreviations1 ,,units4--,abbreviations of various units used in wireless electricity4 ,these abbreviations are usually lower case letters of the ,roman alphabet1 but occasionally ,greek letters are used and other signs4 ,thus amperes is abbreviated amp41 micro1 which means one millionth1 ,greek3 mu1 etc4 ,see ,page #cja ,appendix3 ,useful ,abbreviations4 ,,abbreviations ,,of ,,words ,,and ,,terms4--,letters used instead of words and terms for shortening them up where there is a constant repetition of them1 as ,a4,c4 for alternating current2 ,c4,w4 for continuous waves2 ,v4,t4 for vacuum tube1 etc4 ,see ,page #cab ,appendix3 ,abbreviations of ,common ,terms4 ,,aerial4--,also called antenna4 ,an aerial wire4 ,one or more wires suspended in the air and insulated from its supports4 ,it is the aerial that sends out the waves and receives them4 ,,aerial1 ,,amateur4--,an aerial suitable for sending out #bjj meter wave lengths4 ,such an aerial wire system must not exceed #abj feet in length from the ground up to the aerial switch and from this through the leading-in wire to the end of the aerial4 ,,aerial ,,ammeter4--,see ,ammeter1 ,hot ,wire4 ,,aerial1 ,,bed-,,springs4--,where an outdoor aerial is not practicable bed-springs are often made to serve the purpose4 ,,aerial ,,capacity4--,see ,capacity1 ,aerial4 ,,aerial ,,counterpoise4--,where it is not possible to get a good ground an aerial counterpoise or earth capacity can be used to advantage4 ,the counterpoise is made like the aerial and is supported directly under it close to the ground but insulated from it4 ,,aerial1 ,,directional4--,a flat-top or other aerial that will transmit and receive over greater distances to and from one direction than to and from another4 ,,aerial1 ,,ground4--,signals can be received on a single long wire when it is placed on or buried in the earth or immersed in water4 ,it is also called a ground antenna and an underground aerial4 ,,aerial1 ,,loop4--,also called a coil aerial1 coil antenna1 loop aerial1 loop antenna and when used for the purpose a direction finder4 ,a coil of wire wound on a vertical frame4 ,,aerial ,,resistance4--,see ,resistance1 ,aerial4 ,,aerial ,,switch4--,see ,switch ,aerial4 ,,aerial ,,wire4--7#a7 ,a wire or wires that form the aerial4 7#b7 ,wire that is used for aerials2 this is usually copper or copper alloy4 ,,aerial ,,wire ,,system4--,an aerial and ground wire and that part of the inductance coil which connects them4 ,the open oscillation circuit of a sending or a receiving station4 ,,air ,,core ,,transformer4--,see ,transformer1 ,air ,core4 ,,amateur ,,aerial ,,or ,,antenna4--,see ,aerial1 ,amateur4 ,,alternator4--,an electric machine that generates alternating current4 ,,alphabet1 ,,international ,,code4--,a modified ,morse alphabet of dots and dashes originally used in ,continental ,europe and1 hence1 called the ,continental ,code4 ,it is now used for all general public service wireless communication all over the world and1 hence1 it is called the ,international ,code4 ,see page #cje ,appendix3 ,international ,morse ,code4 ,,alternating ,,current 7,a4,c47--,see ,current4 ,,alternating ,,current ,,transformer4--,see ,transformer4 ,,amateur ,,ground4--,see ,ground1 ,amateur4 ,,ammeter4--,an instrument used for measuring the current strength1 in terms of amperes1 that flows in a circuit4 ,ammeters used for measuring direct and alternating currents make use of the magnetic effects of the currents4 ,high frequency currents make use of the heating effects of the currents4 ,,ammeter1 ,,hot-,,wire4--,high frequency currents are usually measured by means of an instrument which depends on heating a wire or metal strip by the oscillations4 ,such an instrument is often called a thermal ammeter1 radio ammeter and aerial ammeter4 ,,ammeter1 ,,aerial4--,see ,ammeter1 ,hot ,wire4 ,,ammeter1 ,,radio4--,see ,ammeter1 ,hot ,wire4 ,,ampere4--,the current which when passed through a solution of nitrate of silver in water according to certain specifications1 deposits silver at the rate of #j4jjaaahjj of a gram per second4 ,,ampere-,,hour4--,the quantity of electricity transferred by a current of #a ampere in #a hour and is1 therefore1 equal to #cfjj coulombs4 ,,ampere-,,turns4--,when a coil is wound up with a number of turns of wire and a current is made to flow through it1 it behaves like a magnet4 ,b ,the strength of the magnetic field inside of the coil depends on 7#a7 the strength of the current and 7#b7 the number of turns of wire on the coil4 ,thus a feeble current flowing through a large number of turns will produce as strong a magnetic field as a strong current flowing through a few turns of wire4 ,this product of the current in amperes times the number of turns of wire on the coil is called the ampere-turns4 ,,amplification1 ,,audio ,,frequency4--,a current of audio frequency that is amplified by an amplifier tube or other means4 ,,amplification1 ,,cascade4--,see ,cascade ,amplification4 ,,amplification1 ,,radio ,,frequency4--,a current of radio frequency that is amplified by an amplifier tube or other means before it reaches the detector4 ,,amplification1 ,,regenerative4--,a scheme that uses a third circuit to feed back part of the oscillations through a vacuum tube and which increases its sensitiveness when used as a detector and multiplies its action as an amplifier and an oscillator4 ,,amplifier1 ,,audio ,,frequency4--,a vacuum tube or other device that amplifies the signals after passing through the detector4 ,,amplifier1 ,,magnetic4--,a device used for controlling radio frequency currents either by means of a telegraph key or a microphone transmitter4 ,the controlling current flows through a separate circuit from that of the radio current and a fraction of an ampere will control several amperes in the aerial wire4 ,,amplifiers1 ,,multi-,,stage4--,a receiving set using two or more amplifiers4 ,also called cascade amplification4 ,,amplifier1 ,,vacuum ,,tube4--,a vacuum tube that is used either to amplify the radio frequency currents or the audio frequency currents4 ,,amplitude ,,of ,,wave4--,the greatest distance that a point moves from its position of rest4 ,,amplifying ,,transformer1 ,,audio4--,see ,transformer1 ,audio ,amplifying4 ,,amplifying ,,modulator ,,vacuum ,,tube4--,see ,vacuum ,tube1 ,amplifying ,modulator4 ,,amplifying ,,transformer ,,radio4--,see ,transformer1 ,radio ,amplifying4 ,,antenna1 ,,amateur4--,see ,aerial1 ,amateur4 ,,antenna ,,switch4--,see ,switch1 ,aerial4 ,,apparatus ,,symbols4--,see ,symbols1 ,apparatus4 ,,armstrong ,,circuit4--,see ,circuit1 ,armstrong4 ,,atmospherics4--,same as ,static1 which see4 ,,attenuation4--,in ,sending wireless telegraph and telephone messages the amplitude of the electric waves is damped out as the distance increases4 ,this is called attenuation and it increases as the frequency is increased4 ,this is the reason why short wave lengths will not carry as far as long wave lengths4 ,,audio ,,frequency ,,amplifier4--,see ,amplifier1 ,audio ,frequency4 ,,audio ,,frequency ,,amplification4--,see ,amplification1 ,audio ,frequency4 ,,audibility ,,meter4--,see ,meter1 ,audibility4 ,,audio ,,frequency4--,see ,frequency1 ,audio4 ,,audio ,,frequency ,,current4--,see ,current1 ,audio ,frequency4 ,,audion4--,an early trade name given to the vacuum tube detector4 ,,autodyne ,,receptor4--,see ,receptor1 ,autodyne4 ,,auto ,,transformer4--,see ,transformer1 ,auto4 ,,bakelite4--,a manufactured insulating compound4 ,b ,,battery4--,see ,battery ,b4 ,,band1 ,,wave ,,length4--,see ,wave ,length ,band4 ,,basket ,,wound ,,coils4--,see ,coils1 ,inductance4 ,,battery1 ,a4--,the #f-volt storage battery used to heat the filament of a vacuum tube1 detector or amplifier4 ,,battery1 ,b4--,the #bb-a_/b-volt dry cell battery used to energize the plate of a vacuum tube detector or amplifier4 ,,battery1 ,,booster4--,this is the battery that is connected in series with the crystal detector4 ,,battery1 ,c4--,a small dry cell battery sometimes used to give the grid of a vacuum tube detector a bias potential4 ,,battery1 ,,edison ,,storage4--,a storage battery in which the elements are made of nickel and iron and immersed in an alkaline electrolyte4 ,,battery1 ,,lead ,,storage4--,a storage battery in which the elements are made of lead and immersed in an acid electrolyte4 ,,battery ,,poles4--,see ,poles1 ,battery4 ,,battery1 ,,primary4--,a battery that generates current by chemical action4 ,,battery1 ,,storage4--,a battery that develops a current after it has been charged4 ,,beat ,,reception4--,see ,heterodyne ,reception4 ,,bed ,,springs ,,aerial4--,see ,aerial1 ,bed ,springs4 ,,blub ,,blub4--,over modulation in wireless telephony4 ,,broad ,,wave4--,see ,wave1 ,broad4 ,,brush ,,discharge4--,see ,discharge4 ,,buzzer ,,modulation4--,see ,modulation1 ,buzzer4 ,,blue ,,glow ,,discharge4--,see ,discharge4 ,,booster ,,battery4--,see ,battery1 ,booster4 ,,broadcasting4--,sending out intelligence and music from a central station for the benefit of all who live within range of it and who have receiving sets4 ,,capacitance4--,also called by the older name of capacity4 ,the capacity of a condenser1 inductance coil or other device capable of retaining a charge of electricity4 ,capacitance is measured in terms of the microfarad4 ,,capacitive ,,coupling4--,see ,coupling1 ,capacitive4 ,,capacity4--,any object that will retain a charge of electricity2 hence an aerial wire1 a condenser or a metal plate is sometimes called a capacity4 ,,capacity1 ,,aerial4--,the amount to which an aerial wire system can be charged4 ,the capacitance of a small amateur aerial is from #j4jjjb to #j4jjje microfarad4 ,,capacity1 ,,distributed4--,a coil of wire not only has inductance1 but also a certain small capacitance4 ,coils wound with their turns parallel and having a number of layers have a bunched capacitance which produces untoward effects in oscillation circuits4 ,in honeycomb and other stagger wound coils the capacitance is more evenly distributed4 ,,capacity ,,reactance4--,see ,reactance1 ,capacity4 ,,capacity ,,unit4--,see ,farad4 ,,carbon ,,rheostats4--,see ,rheostat1 ,carbon4 ,,carborundum ,,detector4--,see ,detector4 ,,carrier ,,current ,,telephony4--,see ,wired-,wireless4 ,,carrier ,,frequency4--,see ,frequency1 ,carrier4 ,,carrier ,,frequency ,,telephony4--,see ,wired-,wireless4 ,,cascade ,,amplification4--,two or more amplifying tubes hooked up in a receiving set4 ,,cat ,,whisker ,,contact4--,a long1 thin wire which makes contact with the crystal of a detector4 ,,centimeter ,,of ,,capacitance4--,equal to #a4aa microfarads4 ,,centimeter ,,of ,,inductance4--,equal to one one-thousandth part of a microhenry4 ,,cellular ,,coils4--,see ,coils1 ,inductance4 ,c4,g4,s4 ,,electrostatic ,,unit ,,of ,,capacitance4--,see ,centimeter of ,capacitance4 ,,characteristics4--,the special behavior of a device1 such as an aerial1 a detector tube1 etc4 ,,characteristics1 ,,grid4--,see ,grid ,characteristics4 ,,choke ,,coils4--,coils that prevent the high voltage oscillations from surging back into the transformer and breaking down the insulation4 ,,chopper ,,modulation4--,see ,modulation1 ,chopper4 ,,circuit4--,any electrical conductor through which a current can flow4 ,a low voltage current requires a loop of wire or other conductor both ends of which are connected to the source of current before it can flow4 ,a high frequency current will surge in a wire which is open at both ends like the aerial4 ,closed ,circuit4--,a circuit that is continuous4 ,open ,circuit4--,a conductor that is not continuous4 ,coupled ,circuits4--,open and closed circuits connected together by inductance coils1 condensers or resistances4 ,see coupling4 ,close ,coupled ,circuits4--,open and closed circuits connected directly together with a single inductance coil4 ,loose ,coupled ,circuits4--,opened and closed currents connected together inductively by means of a transformer4 ,stand-by ,circuits4--,also called pick-up circuits4 ,when listening-in for possible calls from a number of stations1 a receiver is used which will respond to a wide band of wave lengths4 ,armstrong ,circuits4--,the regenerative circuit invented by ,major ,e4 ,h4 ,armstrong4 ,,close ,,coupled ,,circuits4--,see ,currents1 ,close ,coupled4 ,,closed ,,circuit4--,see ,circuit1 ,closed4 ,,closed ,,core ,,transformer4--,see ,transformer1 ,closed ,core4 ,,code4-- ,continental4--,same as ,international4 ,international4--,on the continent of ,europe land lines use the ,continental ,morse alphabetic code4 ,this code has come to be used throughout the world for wireless telegraphy and hence it is now called the ,international code4 ,it is given on ,page #cje4 ,appendix3 ,international ,morse ,code4 ,morse4--,the code devised by ,samuel ,f4 ,b4 ,morse and which is used on the land lines in the ,u4 ,s4 ,national ,electric4--,a set of rules and requirements devised by the ,national ,board of ,fire ,underwriters for the electrical installations in buildings on which insurance companies carry risks4 ,this code also covers the requirements for wireless installations4 ,a copy may be had from the ,national ,board of ,fire ,underwriters1 ,new ,york ,city1 or from your insurance agent4 ,national ,electric ,safety4--,the ,bureau of ,standards1 ,washington1 ,d4 ,c41 have investigated the precautions which should be taken for the safe operation of all electric equipment4 ,a copy of the ,bureau of ,standards ,handbook ,no4 #c can be had for #dj cents from the ,superintendent of ,documents4 ,,coefficient ,,of ,,coupling4--,see ,coupling1 ,coefficient of4 ,,coil ,,aerial4--,see ,aerial1 ,loop4 ,,coil ,,antenna4--,see ,aerial1 ,loop4 ,,coil1 ,,induction4--,an apparatus for changing low voltage direct currents into high voltage1 low frequency alternating currents4 ,when fitted with a spark gap the high voltage1 low frequency currents are converted into high voltage1 high frequency currents4 ,it is then also called a spark coil and a ,ruhmkorff coil4 ,,coil1 ,,loading4--,a coil connected in the aerial or closed oscillation circuit so that longer wave lengths can be received4 ,,coil1 ,,repeating4--,see ,repeating ,coil4 ,,coil1 ,,rotating4--,one which rotates on a shaft instead of sliding as in a loose coupler4 ,the rotor of a variometer or variocoupler is a rotating coil4 ,,coils1 ,,inductance4--,these are the tuning coils used for sending and receiving sets4 ,for sending sets they are formed of one and two coils1 a single sending coil is generally called a tuning inductance coil1 while a two-coil tuner is called an oscillation transformer4 ,receiving tuning coils are made with a single layer1 single coil1 or a pair of coils1 when it is called an oscillation transformer4 ,some tuning inductance coils have more than one layer1 they are then called lattice wound1 cellular1 basket wound1 honeycomb1 duo-lateral1 stagger wound1 spider-web and slab coils4 ,,commercial ,,frequency4--,see ,frequency1 ,commercial4 ,,condenser1 ,,aerial ,,series4--,a condenser placed in the aerial wire system to cut down the wave length4 ,,condenser1 ,,vernier4--,a small variable condenser used for receiving continuous waves where very sharp tuning is desired4 ,,condenser4--,all conducting objects with their insulation form capacities1 but a condenser is understood to mean two sheets or plates of metal placed closely together but separated by some insulating material4 ,adjustable ,condenser4--,where two or more condensers can be coupled together by means of plugs1 switches or other devices4 ,aerial ,condenser4--,a condenser connected in the aerial4 ,air ,condenser4--,where air only separates the sheets of metal4 ,by-,pass ,condenser4--,a condenser connected in the transmitting currents so that the high frequency currents cannot flow back through the power circuit4 ,filter ,condenser4--,a condenser of large capacitance used in combination with a filter reactor for smoothing out the pulsating direct currents as they come from the rectifier4 ,fixed ,condenser4--,where the plates are fixed relatively to one another4 ,grid ,condenser4--,a condenser connected in series with the grid lead4 ,leyden ,jar ,condenser4--,where glass jars are used4 ,mica ,condenser4--,where mica is used4 ,oil ,condenser4--,where the plates are immersed in oil4 ,paper ,condenser4--,where paper is used as the insulating material4 ,protective4--,a condenser of large capacity connected across the low voltage supply circuit of a transmitter to form a by-path of kick-back oscillations4 ,variable ,condenser4--,where alternate plates can be moved and so made to interleave more or less with a set of fixed plates4 ,vernier4--,a small condenser with a vernier on it so that it can be very accurately varied4 ,it is connected in parallel with the variable condenser used in the primary circuit and is used for the reception of continuous waves where sharp tuning is essential4 ,,condensite4--,a manufactured insulating compound4 ,,conductivity4--,the conductance of a given length of wire of uniform cross section4 ,the reciprocal of resistivity4 ,,contact ,,detectors4--,see ,detectors1 ,contact4 ,,continental ,,code4--,see ,code1 ,continental4 ,,coulomb4--,the quantity of electricity transferred by a current of #a ampere in #a second4 ,,convective ,,discharge4--,see ,discharge4 ,,conventional ,,signals4--,see ,signals1 ,conventional4 ,,counter ,,electromotive ,,force4--,see ,electromotive ,force1 ,counter4 ,,counterpoise4 ,a duplicate of the aerial wire that is raised a few feet above the earth and insulated from it4 ,usually no connection is made with the earth itself4 ,,coupled ,,circuits4--,see ,circuit1 ,coupled4 ,,coupling4--,when two oscillation circuits are connected together either by the magnetic field of an inductance coil1 or by the electrostatic field of a condenser4 ,,coupling1 ,,capacitive4--,oscillation circuits when connected together by condensers instead of inductance coils4 ,,coupling1 ,,coefficient ,,of4--,the measure of the closeness of the coupling between two coils4 ,,coupling1 ,,inductive4--,oscillation circuits when connected together by inductance coils4 ,,coupling1 ,,resistance4--,oscillation circuits connected together by a resistance4 ,,crystal ,,rectifier4--,a crystal detector4 ,,current1 ,,alternating 7,a4,c474--,a low frequency current that surges to and fro in a circuit4 ,,current1 ,,audio ,,frequency4--,a current whose frequency is low enough to be heard in a telephone receiver4 ,such a current usually has a frequency of between #bjj and #b1jjj cycles per second4 ,,current1 ,,plate4--,the current which flows between the filament and the plate of a vacuum tube4 ,,current1 ,,pulsating4--,a direct current whose voltage varies from moment to moment4 ,,current1 ,,radio ,,frequency4--,a current whose frequency is so high it cannot be heard in a telephone receiver4 ,such a current may have a frequency of from #bj1jjj to #aj1jjj1jjj per second4 ,,currents1 ,,high ,,frequency4--7#a7 ,currents that oscillate from #aj1jjj to #cjj1jjj1jjj times per second4 7#b7 ,electric oscillations4 ,,currents1 ,,high ,,potential4--7#a7 ,currents that have a potential of more than #aj1jjj volts4 7#b7 ,high voltage currents4 ,,cycle4--7#a7 ,a series of changes which when completed are again at the starting point4 7#b7 ,a period of time at the end of which an alternating or oscillating current repeats its original direction of flow4 ,,damping4--,the degree to which the energy of an electric oscillation is reduced4 ,in an open circuit the energy of an oscillation set up by a spark gap is damped out in a few swings1 while in a closed circuit it is greatly prolonged1 the current oscillating #bj times or more before the energy is dissipated by the sum of the resistances of the circuit4 ,,decrement4--,the act or process of gradually becoming less4 ,,detector4--,any device that will 7#a7 change the oscillations set up by the incoming waves into direct current1 that is which will rectify them1 or 7#b7 that will act as a relay4 ,carborundum4--,one that uses a carborundum crystal for the sensitive element4 ,carborundum is a crystalline silicon carbide formed in the electric furnace4 ,cat ,whisker ,contact4--,see ,cat ,whisker ,contact4 ,chalcopyrite4--,copper pyrites4 ,a brass colored mineral used as a crystal for detectors4 ,see ,zincite4 ,contact4--,a crystal detector4 ,any kind of a detector in which two dissimilar but suitable solids make contact4 ,ferron4--,a detector in which iron pyrites are used as the sensitive element4 ,galena4--,a detector that uses a galena crystal for the rectifying element4 ,iron ,pyrites4--,a detector that uses a crystal of iron pyrites for its sensitive element4 ,molybdenite4--,a detector that uses a crystal of sulphide of molybdenum for the sensitive element4 ,perikon4--,a detector in which a bornite crystal makes contact with a zincite crystal4 ,silicon4--,a detector that uses a crystal of silicon for its sensitive element4 ,vacuum ,tube4--,a vacuum tube 7which see7 used as a detector4 ,zincite4--,a detector in which a crystal of zincite is used as the sensitive element4 ,,de ,,tuning4--,a method of signaling by sustained oscillations in which the key when pressed down cuts out either some of the inductance or some of the capacity and hence greatly changes the wave length4 ,,dielectric4--,an insulating material between two electrically charged plates in which there is set up an electric strain1 or displacement4 ,,dielectric ,,strain4--,the electric displacement in a dielectric4 ,,directional ,,aerial4--,see ,aerial1 ,directional4 ,,direction ,,finder4--,see ,aerial1 ,loop4 ,,discharge4--7#a7 ,a faintly luminous discharge that takes place from the positive pointed terminal of an induction coil1 or other high potential apparatus2 is termed a brush discharge4 7#b7 ,a continuous discharge between the terminals of a high potential apparatus is termed a convective discharge4 7#c7 ,the sudden breaking-down of the air between the balls forming the spark gap is termed a disruptive discharge2 also called an electric spark1 or just spark for short4 7#d7 ,when a tube has a poor vacuum1 or too large a battery voltage1 it glows with a blue light and this is called a blue glow discharge4 ,,disruptive ,,discharge4--,see ,discharge4 ,,distress ,,call4 ,morse code3 444---444 7,,sos74 ,,distributed ,,capacity4--,see ,capacity1 ,distributed4 ,,double ,,hump ,,resonance ,,curve4--,a resonance curve that has two peaks or humps which show that the oscillating currents which are set up when the primary and secondary of a tuning coil are closely coupled have two frequencies4 ,,duo-,,lateral ,,coils4--,see ,coils1 ,inductance4 ,,duplex ,,communication4--,a wireless telephone system with which it is possible to talk between both stations in either direction without the use of switches4 ,this is known as the duplex system4 ,,earth ,,capacity4--,an aerial counterpoise4 ,,earth ,,connection4--,metal plates or wires buried in the ground or immersed in water4 ,any kind of means by which the sending and receiving apparatus can be connected with the earth4 ,,edison ,,storage ,,battery4--,see ,storage ,battery1 ,edison4 ,,electric ,,energy4--,the power of an electric current4 ,,electric ,,oscillations4--,see ,oscillations1 ,electric4 ,,electric ,,spark4--,see ,discharge1 ,spark4 ,,electricity1 ,,negative4--,the opposite of positive electricity4 ,negative electricity is formed of negative electrons which make up the outside particles of an atom4 ,,electricity1 ,,positive4--,the opposite of negative electricity4 ,positive electricity is formed of positive electrons which make up the inside particles of an atom4 ,,electrodes4--,usually the parts of an apparatus which dip into a liquid and carry a current4 ,the electrodes of a dry battery are the zinc and carbon elements4 ,the electrodes of an ,edison storage battery are the iron and nickel elements1 and the electrodes of a lead storage battery are the lead elements4 ,,electrolytes4--,the acid or alkaline solutions used in batteries4 ,,electromagnetic ,,waves4--,see ,waves1 ,electric4 ,,electromotive ,,force4--,abbreviated emf4 ,the force that drives an electric current along a conductor4 ,also loosely called voltage4 ,,electromotive ,,force1 ,,counter4--,the emf4 that is set up in a direction opposite to that in which the current is flowing in a conductor4 ,,electron4--7#a7 ,a negative particle of electricity that is detached from an atom4 7#b7 ,a negative particle of electricity thrown off from the incandescent filament of a vacuum tube4 ,,electron ,,flow4--,the passage of electrons between the incandescent filament and the cold positively charged plate of a vacuum tube4 ,,electron ,,relay4--,see ,relay1 ,electron4 ,,electron ,,tube4--,a vacuum tube or a gas-content tube used for any purpose in wireless work4 ,see ,vacuum ,tube4 ,,electrose ,,insulators4--,insulators made of a composition material the trade name of which is ,electrose4 ,,energy1 ,,electric4--,see ,electric ,energy4 ,,energy ,,unit4--,the joule1 which see1 ,page #cjh ,appendix3 ,definitions of ,electric and ,magnetic ,units4 ,,fading4--,the sudden variation in strength of signals received from a transmitting station when all the adjustments of both sending and receiving apparatus remain the same4 ,also called swinging4 ,,farad4--,the capacitance of a condenser in which a potential difference of #a volt causes it to have a charge of #a coulomb of electricity4 ,,feed-,,back ,,action4--,feeding back the oscillating currents in a vacuum tube to amplify its power4 ,also called regenerative action4 ,,ferromagnetic ,,control4--,see ,magnetic ,amplifier4 ,,filament4--,the wire in a vacuum tube that is heated to incandescence and which throws off electrons4 ,,filament ,,rheostat4--,see ,rheostat1 ,filament4 ,,filter4--,inductance coils or condensers or both which 7#a7 prevent troublesome voltages from acting on the different circuits1 and 7#b7 smooth out alternating currents after they have been rectified4 ,,filter ,,reactor4--,see ,reactor1 ,filter4 ,,fire ,,underwriters4--,see ,code1 ,national ,electric4 ,,fixed ,,gap4--,see ,gap4 ,,fleming ,,valve4--,a two-electrode vacuum tube4 ,,forced ,,oscillations4--,see ,oscillations1 ,forced4 ,,free ,,oscillations4--,see ,oscillations1 ,free4 ,,frequency1 ,,audio4--7#a7 ,an alternating current whose frequency is low enough to operate a telephone receiver and1 hence1 which can be heard by the ear4 7#b7 ,audio frequencies are usually around #ejj or #a1jjj cycles per second1 but may be as low as #bjj and as high as #aj1jjj cycles per second4 ,carrier4--,a radio frequency wave modulated by an audio frequency wave which results in setting of three radio frequency waves4 ,the principal radio frequency is called the carrier frequency1 since it carries or transmits the audio frequency wave4 ,commercial4--7#a7 ,alternating current that is used for commercial purposes1 namely1 light1 heat and power4 7#b7 ,commercial frequencies now in general use are from #be to #ej cycles per second4 ,natural4--,the pendulum and vibrating spring have a natural frequency which depends on the size1 material of which it is made1 and the friction which it has to overcome4 ,likewise an oscillation circuit has a natural frequency which depends upon its inductance1 capacitance and resistance4 ,radio4--7#a7 ,an oscillating current whose frequency is too high to affect a telephone receiver and1 hence1 cannot be heard by the ear4 7#b7 ,radio frequencies are usually between #bj1jjj and #b1jjj1jjj cycles per second but may be as low as #aj1jjj and as high as #cjj1jjj1jjj cycles per second4 ,spark4--,the number of sparks per second produced by the discharge of a condenser4 ,,gap1 ,,fixed4--,one with fixed electrodes4 ,,gap1 ,,non-,,synchronous4--,a rotary spark gap run by a separate motor which may be widely different from that of the speed of the alternator4 ,,gap1 ,,quenched4--7#a7 ,a spark gap for the impulse production of oscillating currents4 7#b7 ,this method can be likened to one where a spring is struck a single sharp blow and then continues to set up vibrations4 ,,gap1 ,,rotary4--,one having fixed and rotating electrodes4 ,,gap1 ,,synchronous4--,a rotary spark gap run at the same speed as the alternator which supplies the power transformer4 ,such a gap usually has as many teeth as there are poles on the generator4 ,hence one spark occurs per half cycle4 ,,gas-,,content ,,tube4--,see ,vacuum ,tube4 ,,generator ,,tube4--,a vacuum tube used to set up oscillations4 ,as a matter of fact it does not generate oscillations1 but changes the initial low voltage current that flows through it into oscillations4 ,also called an oscillator tube and a power tube4 ,,grid ,,battery4--,see ,battery ,c4 ,,grid ,,characteristics4--,the various relations that could exist between the voltages and currents of the grid of a vacuum tube1 and the values which do exist between them when the tube is in operation4 ,these characteristics are generally shown by curves4 ,,grid ,,condenser4--,see ,condenser1 ,grid4 ,,grid ,,leak4--,a high resistance unit connected in the grid lead of both sending and receiving sets4 ,in a sending set it keeps the voltage of the grid at a constant value and so controls the output of the aerial4 ,in a receiving set it controls the current flowing between the plate and filament4 ,,grid ,,modulation4--,see ,modulation1 ,grid4 ,,grid ,,potential4--,the negative or positive voltage of the grid of a vacuum tube4 ,,grid ,,voltage4--,see ,grid ,potential4 ,,grinders4--,the most common form of ,static1 which see4 ,they make a grinding noise in the headphones4 ,,ground4--,see ,earth ,connection4 ,,ground1 ,,amateur4--,a water-pipe ground4 ,,ground1 ,,waterpipe4--,a common method of grounding by amateurs is to use the waterpipe1 gaspipe or radiator4 ,,guided ,,wave ,,telephony4--,see ,wired ,wireless4 ,,hard ,,tube4--,a vacuum tube in which the vacuum is high1 that is1 exhausted to a high degree4 ,,helix4--7#a7 ,any coil of wire4 7#b7 ,specifically a transmitter tuning inductance coil4 ,,henry4--,the inductance in a circuit in which the electromotive force induced is #a volt when the inducing current varies at the rate of #a ampere per second4 ,,heterodyne ,,reception4--7#a7 ,receiving by the beat method4 7#b7 ,receiving by means of superposing oscillations generated at the receiving station on the oscillations set up in the aerial by the incoming waves4 ,,heterodyne ,,receptor4--,see ,receptor1 ,heterodyne4 ,,high ,,frequency ,,currents4--,see ,currents1 ,high ,frequency4 ,,high ,,frequency ,,resistance4--,see ,resistance1 ,high ,frequency4 ,,high ,,potential ,,currents4--,see ,currents1 ,high ,potential4 ,,high ,,voltage ,,currents4--,see ,currents1 ,high ,potential4 ,,honeycomb ,,coils4--,see ,coils1 ,inductance4 ,,horse-,,power4--,used in rating steam machinery4 ,it is equal to #gdf watts4 ,,hot ,,wire ,,ammeter4--,see ,ammeter1 ,hot ,wire4 ,,howling4--,where more than three stages of radio amplification1 or more than two stages of audio amplification1 are used howling noises are apt to occur in the telephone receivers4 ,,impedance4--,an oscillation circuit has reactance and also resistance1 and when these are combined the total opposition to the current is called impedance4 ,,inductance ,,coils4--,see ,coils1 ,inductance4 ,,inductance ,,coil1 ,,loading4--,see ,coil1 ,loading ,inductance4 ,,inductive ,,coupling4--,see ,coupling1 ,inductive4 ,,inductive ,,reactance4--,see ,reactance1 ,inductive4 ,,induction ,,coil4--,see ,coil1 ,induction4 ,,induction1 ,,mutual4--,induction produced between two circuits or coils close to each other by the mutual interaction of their magnetic fields4 ,,insulation4--,materials used on and around wires and other conductors to keep the current from leaking away4 ,,inspector1 ,,radio4--,a ,u4 ,s4 inspector whose business it is to issue both station and operators' licenses in the district of which he is in charge4 ,,interference4--,the crossing or superposing of two sets of electric waves of the same or slightly different lengths which tend to oppose each other4 ,it is the untoward interference between electric waves from different stations that makes selective signaling so difficult a problem4 ,,intermediate ,,waves4--,see ,waves4 ,,ionic ,,tubes4--,see ,vacuum ,tubes4 ,,international ,,code4--,see ,code1 ,international4 ,,jamming4--,waves that are of such length and strength that when they interfere with incoming waves they drown them out4 ,,joule4--,the energy spent in #a second by a flow of #a ampere in #a ohm4 ,,joule',s ,,law4--,the relation between the heat produced in seconds to the resistance of the circuit1 to the current flowing in it4 ,,kenotron4--,the trade name of a vacuum tube rectifier made by the ,radio ,corporation of ,america4 ,,kick-,,back4--,oscillating currents that rise in voltage and tend to flow back through the circuit that is supplying the transmitter with low voltage current4 ,,kick-,,back ,,prevention4--,see ,prevention1 ,kick-,back4 ,,kilowatt4--#a1jjj watts4 ,,lambda4--,see ,pages #cja1 #cjb4 ,appendix3 ,useful ,abbreviations4 ,,lattice ,,wound ,,coils4--,see ,coils1 ,inductance4 ,,lightning ,,switch4--,see ,switch1 ,lightning4 ,,line ,,radio ,,communication4--,see ,wired ,wireless4 ,,line ,,radio ,,telephony4--,see ,telephony1 ,line ,radio4 ,,litzendraht4--,a conductor formed of a number of fine copper wires either twisted or braided together4 ,it is used to reduce the skin effect4 ,see ,resistance1 ,high ,frequency4 ,,load ,,flicker4--,the flickering of electric lights on lines that supply wireless transmitting sets due to variations of the voltage on opening and closing the key4 ,,loading ,,coil4--,see ,coil1 ,loading4 ,,long ,,waves4--,see ,waves4 ,,loop ,,aerial4--,see ,aerial1 ,loop4 ,,loose ,,coupled ,,circuits4--,see ,circuits1 ,loose ,coupled4 ,,loud ,,speaker4--,a telephone receiver connected to a horn1 or a specially made one1 that reproduces the incoming signals1 words or music loud enough to be heard by a room or an auditorium full of people1 or by large crowds out-doors4 ,,magnetic ,,poles4--,see ,poles1 ,magnetic4 ,,megohm4--,one million ohms4 ,,meter1 ,,audibility4--,an instrument for measuring the loudness of a signal by comparison with another signal4 ,it consists of a pair of headphones and a variable resistance which have been calibrated4 ,,mho4--,the unit of conductance4 ,as conductance is the reciprocal of resistance it is measured by the reciprocal ohm or mho4 ,,mica4--,a transparent mineral having a high insulating value and which can be split into very thin sheets4 ,it is largely used in making condensers both for transmitting and receiving sets4 ,,microfarad4--,the millionth part of a farad4 ,,microhenry4--,the millionth part of a farad4 ,,micromicrofarad4--,the millionth part of a microfarad4 ,,microhm4--,the millionth part of an ohm4 ,,microphone ,,transformer4--,see ,transformer1 ,microphone4 ,,microphone ,,transmitter4--,see ,transmitter1 ,microphone4 ,,milli-,,ammeter4--,an ammeter that measures a current by the one-thousandth of an ampere4 ,,modulation4--7#a7 ,inflection or varying the voice4 7#b7 ,varying the amplitude of oscillations by means of the voice4 ,,modulation1 ,,buzzer4--,the modulation of radio frequency oscillations by a buzzer which breaks up the sustained oscillations of a transmitter into audio frequency impulses4 ,,millihenry4--,the thousandth part of a henry4 ,,modulation1 ,,chopper4--,the modulation of radio frequency oscillations by a chopper which breaks up the sustained oscillations of a transmitter into audio frequency impulses4 ,,modulation1 ,,grid4--,the scheme of modulating an oscillator tube by connecting the secondary of a transformer1 the primary of which is connected with a battery and a microphone transmitter1 in the grid lead4 ,,modulation1 ,,over4--,see ,blub ,blub4 ,,modulation1 ,,plate4--,modulating the oscillations set up by a vacuum tube by varying the current impressed on the plate4 ,,modulator ,,tube4--,a vacuum tube used as a modulator4 ,,motion1 ,,wave4--7#a7 ,the to and fro motion of water at sea4 7#b7 ,waves transmitted by1 in and through the air1 or sound waves4 7#c7 ,waves transmitted by1 in and through the ether1 or electromagnetic waves1 or electric waves for short4 ,,motor-,,generator4--,a motor and a dynamo built to run at the same speed and mounted on a common base1 the shafts being coupled together4 ,in wireless it is used for changing commercial direct current into direct current of higher voltages for energizing the plate of a vacuum tube oscillator4 ,,multi-,,stage ,,amplifiers4--,see ,amplifiers1 ,multi-,stage4 ,,mutual ,,induction4--,see ,induction1 ,mutual4 ,,mush4--,irregular intermediate frequencies set up by arc transmitters which interfere with the fundamental wave lengths4 ,,mushy ,,note4--,a note that is not clear cut1 and hence hard to read1 which is received by the heterodyne method when damped waves or modulated continuous waves are being received4 ,,national ,,electric ,,code4--,see ,code1 ,national ,electric4 ,,national ,,electric ,,safety ,,code4--,see ,code1 ,national ,electric ,safety4 ,,negative ,,electricity4--,see ,electricity1 ,negative4 ,,non-,,synchronous ,,gap4--,see ,gap1 ,non-,synchronous4 ,,ohm4--,the resistance of a thread of mercury at the temperature of melting ice1 #ad4deba grams in mass1 of uniform cross-section and a length of #ajf4cjj centimeters4 ,,ohm',s ,,law4--,the important fixed relation between the electric current1 its electromotive force and the resistance of the conductor in which it flows4 ,,open ,,circuit4--,see ,circuit1 ,open4 ,,open ,,core ,,transformer4--,see ,transformer1 ,open ,core4 ,,oscillation ,,transformer4--,see ,transformer1 ,oscillation4 ,,oscillations1 ,,electric4--,a current of high frequency that surges through an open or a closed circuit4 7#a7 ,electric oscillations may be set up by a spark gap1 electric arc or a vacuum tube1 when they have not only a high frequency but a high potential1 or voltage4 7#b7 ,when electric waves impinge on an aerial wire they are transformed into electric oscillations of a frequency equal to those which emitted the waves1 but since a very small amount of energy is received their potential or voltage is likewise very small4 ,sustained4--,oscillations in which the damping factor is small4 ,damped4--,oscillations in which the damping factor is large4 ,free4--,when a condenser discharges through an oscillation circuit1 where there is no outside electromotive force acting on it1 the oscillations are said to be free4 ,forced4--,oscillations that are made to surge in a circuit whose natural period is different from that of the oscillations set up in it4 ,,oscillation ,,transformer4--,see ,transformer4 ,,oscillation ,,valve4--,see ,vacuum ,tube4 ,,oscillator ,,tube4--,a vacuum tube which is used to produce electric oscillations4 ,,over ,,modulation4--,see ,blub ,blub4 ,,pancake ,,oscillation ,,transformer4--,disk-shaped coils that are used for receiving tuning inductances4 ,,permeability1 ,,magnetic4--,the degree to which a substance can be magnetized4 ,iron has a greater magnetic permeability than air4 ,,phase4--,a characteristic aspect or appearance that takes place at the same point or part of a cycle4 ,,pick-,,up ,,circuits4--,see ,circuits1 ,stand-by4 ,,plate ,,circuit ,,reactor4--,see ,reactor1 ,plate ,circuit4 ,,plate ,,current4--,see ,current1 ,plate4 ,,plate ,,modulation4--,see ,modulation1 ,plate4 ,,plate ,,voltage4--,see ,foliage1 ,plate4 ,,poles1 ,,battery4--,the positive and negative terminals of the elements of a battery4 ,on a storage battery these poles are marked and - respectively4 ,,poles1 ,,magnetic4--,the ends of a magnet4 ,,positive ,,electricity4--,see ,electricity1 ,positive4 ,,potential ,,difference4--,the electric pressure between two charged conductors or surfaces4 ,,potentiometer4--,a variable resistance used for subdividing the voltage of a current4 ,a voltage divider4 ,,power ,,transformer4--,see ,transformer1 ,power4 ,,power ,,tube4--,see ,generator ,tube4 ,,primary ,,battery4--,see ,battery1 ,primary4 ,,prevention1 ,,kick-,,back4--,a choke coil placed in the power circuit to prevent the high frequency currents from getting into the transformer and breaking down the insulation4 ,q ,s ,t4--,an abbreviation used in wireless communication for 7#a7 the question ,have you received the general call8 and 7#b7 the notice1 ,general call to all stations4 ,,quenched ,,gap4--,see ,gap1 ,quenched4 ,,radiation4--,the emission1 or throwing off1 of electric waves by an aerial wire system4 ,,radio ,,ammeter4--,see ,ammeter1 ,hot ,wire4 ,,radio ,,frequency4--,see ,frequency1 ,radio4 ,,radio ,,frequency ,,amplification4--,see ,amplification1 ,radio ,frequency4 ,,radio ,,frequency ,,current4--,see ,current1 ,radio ,frequency4 ,,radio ,,inspector4--,see ,inspector1 ,radio4 ,,radiotron4--,the trade name of vacuum tube detectors1 amplifiers1 oscillators and modulators made by the ,radio ,corporation of ,america4 ,,radio ,,waves4--,see ,waves1 ,radio4 ,,reactance4--,when a circuit has inductance and the current changes in value1 it is opposed by the voltage induced by the variation of the current4 ,,reactance1 ,,capacity4--,the capacity reactance is the opposition offered to a current by a capacity4 ,it is measured as a resistance1 that is1 in ohms4 ,,receiving ,,tuning ,,coils4--,see ,coils1 ,inductance4 ,,receiver1 ,,loud ,,speaking4--,see ,loud ,speakers4 ,,receiver1 ,,watch ,,case4--,a compact telephone receiver used for wireless reception4 ,,reactance1 ,,inductive4--,the inductive reactance is the opposition offered to the current by an inductance coil4 ,it is measured as a resistance1 that is1 in ohms4 ,,reactor1 ,,filter4--,a reactance coil for smoothing out the pulsating direct currents as they come from the rectifier4 ,,reactor1 ,,plate ,,circuit4--,a reactance coil used in the plate circuit of a wireless telephone to keep the direct current supply at a constant voltage4 ,,receiver4--7#a7 ,a telephone receiver4 7#b7 ,an apparatus for receiving signals1 speech or music4 7#c7 ,better called a receptor to distinguish it from a telephone receiver4 ,,rectifier4--7#a7 ,an apparatus for changing alternating current into pulsating direct current4 7#b7 ,specifically in wireless 7a7 a crystal or vacuum tube detector1 and 7b7 a two-electrode vacuum tube used for changing commercial alternating current into direct current for wireless telephony4 ,,regenerative ,,amplification4--,see ,amplification1 ,regenerative4 ,,receptor4--,a receiving set4 ,,receptor1 ,,autodyne4--,a receptor that has a regenerative circuit and the same tube is used as a detector and as a generator of local oscillations4 ,,receptor1 ,,beat4--,a heterodyne receptor4 ,,receptor1 ,,heterodyne4--,a receiving set that uses a separate vacuum tube to set up the second series of waves for beat reception4 ,,regenerative ,,action4--,see ,feed-,back ,action4 ,,regenerative ,,amplification4--,see ,amplification1 ,regenerative4 ,,relay1 ,,electron4--,a vacuum tube when used as a detector or an amplifier4 ,,repeating ,,coil4--,a transformer used in connecting up a wireless receiver with a wire transmitter4 ,,resistance4--,the opposition offered by a wire or other conductor to the passage of a current4 ,,resistance1 ,,aerial4--,the resistance of the aerial wire to oscillating currents4 ,this is greater than its ordinary ohmic resistance due to the skin effect4 ,see ,resistance1 ,high ,frequency4 ,,resistance ,,box4--,see ,resistor4 ,,resistance ,,coupling4--,see ,coupling1 ,resistance4 ,,resistance1 ,,high ,,frequency4--,when a high frequency current oscillates on a wire two things take place that are different than when a direct or alternating current flows through it1 and these are 7#a7 the current inside of the wire lags behind that of the current on the surface1 and 7#b7 the amplitude of the current is largest on the surface and grows smaller as the center of the wire is reached4 ,this uneven distribution of the current is known as the skin effect and it amounts to the same thing as reducing the size of the wire1 hence the resistance is increased4 ,,resistivity4--,the resistance of a given length of wire of uniform cross section4 ,the reciprocal of conductivity4 ,,resistor4--,a fixed or variable resistance unit or a group of such units4 ,variable resistors are also called resistance boxes and more often rheostats4 ,,resonance4--7#a7 ,simple resonance of sound is its increase set up by one body by the sympathetic vibration of a second body4 7#b7 ,by extension the increase in the amplitude of electric oscillations when the circuit in which they surge has a natural period that is the same1 or nearly the same1 as the period of the first oscillation circuit4 ,,rheostat4--,a variable resistance unit4 ,see ,resistor4 ,,rheostat1 ,,carbon4--,a carbon rod1 or carbon plates or blocks1 when used as variable resistances4 ,,rheostat1 ,,filament4--,a variable resistance used for keeping the current of the storage battery which heats the filament of a vacuum tube at a constant voltage4 ,,rotating ,,coil4--,see ,coil4 ,,rotary ,,gap4--,see ,gap4 ,,rotor4--,the rotating coil of a variometer or a variocoupler4 ,,ruhmkorff ,,coil4--,see ,coil1 ,induction4 ,,saturation4--,the maximum plate current that a vacuum tube will take4 ,,sensitive ,,spots4--,spots on detector crystals that are sensitive to the action of electric oscillations4 ,,short ,,waves4--,see ,waves4 ,,side ,,waves4--,see ,wave ,length ,band4 ,,signals1 ,,conventional4--7#a7 ,the ,international ,morse alphabet and numeral code1 punctuation marks1 and a few important abbreviations used in wireless telegraphy4 7#b7 ,dot and dash signals for distress call1 invitation to transmit1 etc4 ,now used for all general public service wireless communication4 ,,skin ,,effect4--,see ,resistance1 ,high ,frequency4 ,,soft ,,tube4--,a vacuum tube in which the vacuum is low1 that is1 it is not highly exhausted4 ,,space ,,charge ,,effect4--,the electric field intensity due to the pressure of the negative electrons in the space between the filament and plate which at last equals and neutralizes that due to the positive potential of the plate so that there is no force acting on the electrons near the filament4 ,,spark4--,see ,discharge4 ,,spark ,,coil4--,see ,coil1 ,induction4 ,,spark ,,discharge4--,see ,spark1 ,electric4 ,,spark ,,frequency4--,see ,frequency1 ,spark4 ,,spark ,,gap4--7#a7 ,a spark gap1 without the hyphen1 means the apparatus in which sparks take place2 it is also called a spark discharger4 7#b7 ,spark-gap1 with the hyphen1 means the air-gap between the opposed faces of the electrodes in which sparks are produced4 ,plain4--,a spark gap with fixed electrodes4 ,rotary4--,a spark gap with a pair of fixed electrodes and a number of electrodes mounted on a rotating element4 ,quenched4--,a spark gap formed of a number of metal plates placed closely together and insulated from each other4 ,,spider ,,web ,,inductance ,,coil4--,see ,coil1 ,spider ,web ,inductance4 ,,spreader4--,a stick of wood1 or spar1 that holds the wires of the aerial apart4 ,,stagger ,,wound ,,coils4--,see ,coils1 ,inductance4 ,,stand-,,by ,,circuits4--,see ,circuits1 ,stand-,by4 ,,static4--,also called atmospherics1 grinders1 strays1 ,x's1 and1 when bad enough1 by other names4 ,it is an electrical disturbance in the atmosphere which makes noises in the telephone receiver4 ,,stator4--,the fixed or stationary coil of a variometer or a variocoupler4 ,,storage ,,battery4--,see ,battery1 ,storage4 ,,stray ,,elimination4--,a method for increasing the strength of the signals as against the strength of the strays4 ,see ,static4 ,,strays4--,see ,static4 ,,stranded ,,wire4--,see ,wire1 ,stranded4 ,,super-,,heterodyne ,,receptor4--,see ,heterodyne1 ,super4 ,,swinging4--,see ,fading4 ,,switch1 ,,aerial4--,a switch used to change over from the sending to the receiving set1 and the other way about1 and connect them with the aerial4 ,,switch1 ,,lightning4--,the switch that connects the aerial with the outside ground when the apparatus is not in use4 ,,symbols1 ,,apparatus4--,also called conventional symbols4 ,these are diagrammatic lines representing various parts of apparatus so that when a wiring diagram of a transmitter or a receptor is to be made it is only necessary to connect them together4 ,they are easy to make and easy to read4 ,see ,page #cjg ,appendix3 ,symbols ,used for ,apparatus4 ,,synchronous ,,gap4--,see ,gap1 ,synchronous4 ,,telephony1 ,,line ,,radio4--,see ,wired ,wireless4 ,,thermal ,,ammeter4--,see ,ammeter1 ,hot ,wire4 ,,three ,,electrode ,,vacuum ,,tube4--,see ,vacuum ,tube1 ,three ,electrode4 ,,tikker4--,a slipping contact device that breaks up the sustained oscillations at the receiving end into groups so that the signals can be heard in the head phones4 ,the device usually consists of a fine steel or gold wire slipping in the smooth groove of a rotating brass wheel4 ,,transformer4--,a primary and a secondary coil for stepping up or down a primary alternating or oscillating current4 ,a4 ,c4--,see ,power ,transformer4 ,air ,cooled4--,a transformer in which the coils are exposed to the air4 ,air ,core4--,with high frequency currents it is the general practice not to use iron cores as these tend to choke off the oscillations4 ,hence the core consists of the air inside of the coils4 ,auto4--,a single coil of wire in which one part forms the primary and the other part the secondary by bringing out an intermediate tap4 ,audio ,amplifying4--,this is a transformer with an iron core and is used for frequencies up to say #c1jjj4 ,closed ,core4--,a transformer in which the path of the magnetic flux is entirely through iron4 ,power transformers have closed cores4 ,microphone4--,a small transformer for modulating the oscillations set up by an arc or a vacuum tube oscillator4 ,oil ,cooled4--,a transformer in which the coils are immersed in oil4 ,open ,core4--,a transformer in which the path of the magnetic flux is partly through iron and partly through air4 ,induction coils have open cores4 ,oscillation4--,a coil or coils for transforming or stepping down or up oscillating currents4 ,oscillation transformers usually have no iron cores when they are also called air core transformers4 ,power4--,a transformer for stepping down a commercial alternating current for lighting and heating the filament and for stepping up the commercial a4c41 for charging the plate of a vacuum tube oscillator4 ,radio ,amplifying4--,this is a transformer with an air core4 ,it does not in itself amplify but is so called because it is used in connection with an amplifying tube4 ,,transmitter1 ,,microphone4--,a telephone transmitter of the kind that is used in the ,bell telephone system4 ,,transmitting ,,tuning ,,coils4--,see ,coils1 ,inductance4 ,,tuning4--,when the open and closed oscillation circuits of a transmitter or a receptor are adjusted so that both of the former will permit electric oscillations to surge through them with the same frequency1 they are said to be tuned4 ,likewise1 when the sending and receiving stations are adjusted to the same wave length they are said to be tuned4 ,coarse ,tuning4--,the first adjustment in the tuning oscillation circuits of a receptor is made with the inductance coil and this tunes them coarse1 or roughly4 ,fine ,tuning4--,after the oscillation circuits have been roughly tuned with the inductance coil the exact adjustment is obtained with the variable condenser and this is fine tuning4 ,sharp4--,when a sending set will transmit or a receiving set will receive a wave of given length only it is said to be sharply tuned4 ,the smaller the decrement the sharper the tuning4 ,,tuning ,,coils4--,see ,coils1 ,inductance4 ,,two ,,electrode ,,vacuum ,,tube4--,see ,vacuum ,tube1 ,two ,electrode4 ,,vacuum ,,tube4--,a tube with two or three electrodes from which the air has been exhausted1 or which is filled with an inert gas1 and used as a detector1 an amplifier1 an oscillator or a modulator in wireless telegraphy and telephony4 ,amplifier4--,see ,amplifier1 ,vacuum ,tube4 ,amplifying ,modulator4--,a vacuum tube used for modulating and amplifying the oscillations set up by the sending set4 ,gas ,content4--,a tube made like a vacuum tube and used as a detector but which contains an inert gas instead of being exhausted4 ,hard4--,see ,hard ,tube4 ,rectifier4--7#a7 ,a vacuum tube detector4 7#b7 a two-electrode vacuum tube used for changing commercial alternating current into direct current for wireless telephony4 ,soft4--,see ,soft ,tube4 ,three ,electrode4--,a vacuum tube with three electrodes1 namely a filament1 a grid and a plate4 ,two ,electrode4--,a vacuum tube with two electrodes1 namely the filament and the plate4 ,,valve4--,see ,vacuum ,tube4 ,,valve1 ,,fleming4--,see ,fleming ,valve4 ,,variable ,,condenser4--,see ,condenser1 ,variable4 ,,variable ,,inductance4--,see ,inductance1 ,variable4 ,,variable ,,resistance4--,see ,resistance1 ,variable4 ,,variocoupler4--,a tuning device for varying the inductance of the receiving oscillation circuits4 ,it consists of a fixed and a rotatable coil whose windings are not connected with each other4 ,,variometer4--,a tuning device for varying the inductance of the receiving oscillation currents4 ,it consists of a fixed and a rotatable coil with the coils connected in series4 ,,vernier ,,condenser4--,see ,condenser1 ,vernier4 ,,volt4--,the electromotive force which produces a current of #a ampere when steadily applied to a conductor the resistance of which is one ohm4 ,,voltage ,,divider4--,see ,potentiometer4 ,,voltage1 ,,plate4--,the voltage of the current that is used to energize the plate of a vacuum tube4 ,,voltmeter4--,an instrument for measuring the voltage of an electric current4 ,,watch ,,case ,,receiver4--,see ,receiver1 ,watch ,case4 ,,water-,,pipe ,,ground4--,see ,ground1 ,water-,pipe4 ,,watt4--,the power spent by a current of #a ampere in a resistance of #a ohm4 ,,wave1 ,,broad4--,a wave having a high decrement1 when the strength of the signals is nearly the same over a wide range of wave lengths4 ,,wave ,,length4--,every wave of whatever kind has a length4 ,the wave length is usually taken to mean the distance between the crests of two successive waves4 ,,wave ,,length ,,band4--,in wireless reception when continuous waves are being sent out and these are modulated by a microphone transmitter the different audio frequencies set up corresponding radio frequencies and the energy of these are emitted by the aerial2 this results in waves of different lengths1 or a band of waves as it is called4 ,,wave ,,meter4--,an apparatus for measuring the lengths of electric waves set up in the oscillation circuits of sending and receiving sets4 ,,wave ,,motion4--,disturbances set up in the surrounding medium as water waves in and on the water1 sound waves in the air and electric waves in the ether4 ,,waves4--,see ,wave ,motion4 ,,waves1 ,,electric4--,electromagnetic waves set up in and transmitted by and through the ether4 ,continuous4 ,abbreviated ,c4,w4--,waves that are emitted without a break from the aerial4 ,also called undamped waves4 ,discontinuous4--,waves that are emitted periodically from the aerial4 ,also called damped waves4 ,damped4--,see ,discontinuous ,waves4 ,intermediate4--,waves from #fjj to #b1jjj meters in length4 ,long4--,waves over #b1jjj meters in length4 ,radio4--,electric waves used in wireless telegraphy and telephony4 ,short4--,waves up to #fjj meters in length4 ,wireless4--,electric waves used in wireless telegraphy and telephony4 ,undamped4--,see ,continuous ,waves4 ,,wireless ,,telegraph ,,code4--,see ,code1 ,international4 ,,wire1 ,,enamelled4--,wire that is given a thin coat of enamel which insulates it4 ,,wire1 ,,phosphor ,,bronze4--,a very strong wire made of an alloy of copper and containing a trace of phosphorus4 ,,wired ,,wireless4--,continuous waves of high frequency that are sent over telephone wires instead of through space4 ,also called line radio communication2 carrier frequency telephony1 carrier current telephony2 guided wave telephony and wired wireless4 ,x',s4--,see ,static4 ,,zincite4--,see ,detector4 ,,wireless ,,don',,ts ,,aerial ,,wire ,,don',,ts ,don't use iron wire for your aerial4 ,don't fail to insulate it well at both ends4 ,don't have it longer than #ge feet for sending out a #bjj-meter wave4 ,don't fail to use a lightning arrester1 or better1 a lightning switch1 for your receiving set4 ,don't fail to use a lightning switch with your transmitting set4 ,don't forget you must have an outside ground4 ,don't fail to have the resistance of your aerial as small as possible4 ,use stranded wire4 ,don't fail to solder the leading-in wire to the aerial4 ,don't fail to properly insulate the leading-in wire where it goes through the window or wall4 ,don't let your aerial or leading-in wire touch trees or other objects4 ,don't let your aerial come too close to overhead wires of any kind4 ,don't run your aerial directly under1 or over1 or parallel with electric light or other wires4 ,don't fail to make a good ground connection with the water pipe inside4 ,,transmitting ,,don',,ts ,don't attempt to send until you get your license4 ,don't fail to live up to every rule and regulation4 ,don't use an input of more than #a_/b a kilowatt if you live within #e nautical miles of a naval station4 ,don't send on more than a #bjj-meter wave if you have a restricted or general amateur license4 ,don't use spark gap electrodes that are too small or they will get hot4 ,don't use too long or too short a spark gap4 ,the right length can be found by trying it out4 ,don't fail to use a safety spark gap between the grid and the filament terminals where the plate potential is above #b1jjj volts4 ,don't buy a motor-generator set if you have commercial alternating current in your home4 ,don't overload an oscillation vacuum tube as it will greatly shorten its life4 ,use two in parallel4 ,don't operate a transmitting set without a hot-wire ammeter in the aerial4 ,don't use solid wire for connecting up the parts of transmitters4 ,use stranded or braided wire4 ,don't fail to solder each connection4 ,don't use soldering fluid1 use rosin4 ,don't think that all of the energy of an oscillation tube cannot be used for wave lengths of #bjj meters and under4 ,it can be if the transmitting set and aerial are properly designed4 ,don't run the wires of oscillation circuits too close together4 ,don't cross the wires of oscillation circuits except at right angles4 ,don't set the transformer of a transmitting set nearer than #c feet to the condenser and tuning coil4 ,don't use a rotary gap in which the wheel runs out of true4 ,,receiving ,,don',,ts ,don't expect to get as good results with a crystal detector as with a vacuum tube detector4 ,don't be discouraged if you fail to hit the sensitive spot of a crystal detector the first time--or several times thereafter4 ,don't use a wire larger than ,no4 #hj for the wire electrode of a crystal detector4 ,don't try to use a loud speaker with a crystal detector receiving set4 ,don't expect a loop aerial to give worthwhile results with a crystal detector4 ,don't handle crystals with your fingers as this destroys their sensitivity4 ,use tweezers or a cloth4 ,don't imbed the crystal in solder as the heat destroys its sensitivity4 ,use ,wood's metal1 or some other alloy which melts at or near the temperature of boiling water4 ,don't forget that strong static and strong signals sometimes destroy the sensitivity of crystals4 ,don't heat the filament of a vacuum tube to greater brilliancy than is necessary to secure the sensitiveness required4 ,don't use a plate voltage that is less or more than it is rated for4 ,don't connect the filament to a lighting circuit4 ,don't use dry cells for heating the filament except in a pinch4 ,don't use a constant current to heat the filament1 use a constant voltage4 ,don't use a vacuum tube in a horizontal position unless it is made to be so used4 ,don't fail to properly insulate the grid and plate leads4 ,don't use more than #a_/c of the rated voltage on the filament and on the plate when trying it out for the first time4 ,don't fail to use alternating current for heating the filament where this is possible4 ,don't fail to use a voltmeter to find the proper temperature of the filament4 ,don't expect to get results with a loud speaker when using a single vacuum tube4 ,don't fail to protect your vacuum tubes from mechanical shocks and vibration4 ,don't fail to cut off the ,a battery entirely from the filament when you are through receiving4 ,don't switch on the ,a battery current all at once through the filament when you start to receive4 ,don't expect to get the best results with a gas-content detector tube without using a potentiometer4 ,don't connect a potentiometer across the ,b battery or it will speedily run down4 ,don't expect to get as good results with a single coil tuner as you would with a loose coupler4 ,don't expect to get as good results with a two-coil tuner as with one having a third1 or tickler1 coil4 ,don't think you have to use a regenerative circuit1 that is1 one with a tickler coil1 to receive with a vacuum tube detector4 ,don't think you are the only amateur who is troubled with static4 ,don't expect to eliminate interference if the amateurs around you are sending with spark sets4 ,don't lay out or assemble your set on a panel first4 ,connect it up on a board and find out if everything is right4 ,don't try to connect up your set without a wiring diagram in front of you4 ,don't fail to shield radio frequency amplifiers4 ,don't set the axes of the cores of radio frequency transformers in a line4 ,set them at right angles to each other4 ,don't use wire smaller than ,no4 #ad for connecting up the various parts4 ,don't fail to adjust the ,b battery after putting in a fresh vacuum tube1 as its sensitivity depends largely on the voltage4 ,don't fail to properly space the parts where you use variometers4 ,don't fail to put a copper shield between the variometer and the variocoupler4 ,don't fail to keep the leads to the vacuum tube as short as possible4 ,don't throw your receiving set out of the window if it howls4 ,try placing the audio-frequency transformers farther apart and the cores of them at right angles to each other4 ,don't use condensers with paper dielectrics for an amplifier receiving set or it will be noisy4 ,don't expect as good results with a loop aerial1 or when using the bed springs1 as an out-door aerial will give you4 ,don't use an amplifier having a plate potential of less than #ajj volts for the last step where a loud speaker is to be used4 ,don't try to assemble a set if you don't know the difference between a binding post and a blue print4 ,buy a set ready to use4 ,don't expect to get ,arlington time signals and the big cableless stations if your receiver is made for short wave lengths4 ,don't take your headphones apart4 ,you are just as apt to spoil them as you would a watch4 ,don't expect to get results with a ,bell telephone receiver4 ,don't forget that there are other operators using the ether besides yourself4 ,don't let your ,b battery get damp and don't let it freeze4 ,don't try to recharge your ,b battery unless it is constructed for the purpose4 ,,storage ,,battery ,,don',,ts ,don't connect a source of alternating current direct to your storage battery4 ,you have to use a rectifier4 ,don't connect the positive lead of the charging circuit with the negative terminal of your storage battery4 ,don't let the electrolyte get lower than the tops of the plates of your storage battery4 ,don't fail to look after the condition of your storage battery once in a while4 ,don't buy a storage battery that gives less than #f volts for heating the filament4 ,don't fail to keep the specific gravity of the electrolyte of your storage battery between #a4bbe and #a4cjj ,baume4 ,this you can do with a hydrometer4 ,don't fail to recharge your storage battery when the hydrometer shows that the specific gravity of the electrolyte is close to #a4bbe4 ,don't keep charging the battery after the hydrometer shows that the specific gravity is #a4bhe4 ,don't let the storage battery freeze4 ,don't let it stand for longer than a month without using unless you charge it4 ,don't monkey with the storage battery except to add a little sulphuric acid to the electrolyte from time to time4 ,if anything goes wrong with it better take it to a service station and let the expert do it4 ,,extra ,,don',,ts ,don't think you have an up-to-date transmitting station unless you are using ,c4,w4 ,don't use a wire from your lightning switch down to the outside ground that is smaller than ,no4 #d4 ,don't try to operate your spark coil with #aaj-volt direct lighting current without connecting in a rheostat4 ,don't try to operate your spark coil with #aaj-volt alternating lighting current without connecting in an electrolytic interrupter4 ,don't try to operate an alternating current power transformer with #aaj-volt direct current without connecting in an electrolytic interruptor4 ,don't--no never--connect one side of the spark gap to the aerial wire and the other side of the spark gap to the ground4 ,the ,government won't have it--that's all4 ,don't try to tune your transmitter to send out waves of given length by guesswork4 ,use a wavemeter4 ,don't use hard fiber for panels4 ,it is a very poor insulator where high frequency currents are used4 ,don't think you are the only one who doesn't know all about wireless4 ,wireless is a very complex art and there are many things that those experienced have still to learn4 ,,the ,,end4