. Practical wireless telegraphy; a complete text book for students of radio communication . Referring to the dia-gram (Fig. 279) : Thechoking inductances areindicated at C-1 and C-2;the regulating resistancefor the arc shown at Ris connected in serieswith the blow-out mag-nets placed at right anglesto the arc. A source ofdirect current of 500volts is connected to thearc gap, the plus pole ofwhich is constructed ofcopper, the minus pole ofcarbon. An arc transmitter ofthis type is adjusted foroperation as follows:The arc is struck at lowvoltage by connectinglarge values of resist-ance in the cir
. Practical wireless telegraphy; a complete text book for students of radio communication . Referring to the dia-gram (Fig. 279) : Thechoking inductances areindicated at C-1 and C-2;the regulating resistancefor the arc shown at Ris connected in serieswith the blow-out mag-nets placed at right anglesto the arc. A source ofdirect current of 500volts is connected to thearc gap, the plus pole ofwhich is constructed ofcopper, the minus pole ofcarbon. An arc transmitter ofthis type is adjusted foroperation as follows:The arc is struck at lowvoltage by connectinglarge values of resist-ance in the circuit at gap is then length-ened out and the voltageincreased until the aerial Fig. 280—Details and Connections of the Alexanderson Radio Frequency ^.^ter indicates aAlternator. maximum readmg. /; is , ,, , A • ^7 ■ , t °*^^ ° critical length of arc gap gives the maximum value of antenna current and this is the adjustmentalways to be aimed for. The condenser shunted across the arc (Fig. 279) acts as a by-pass for the radio-frequentcurrents flowing in the antenna circuit. ^. TRANSMITTERS OF UNDAMPED OSCILLATIONS. 267 215. Signalling with the Arc Transmitter.—It is obvious that a telegraphkey cannot be placed in series with the arc gap for signalling and, in consequence,the formation of the Morse characters is usually effected by changing the inr-ductance of the antenna circuit at coil L-1, Fig. 279. When the lever of the keyK is released, the radiated wave, for example, is 6,900 meters in length, but uponpressing the key, a few additional turns of wire are inserted in the antenna circuit;the wave length thus is increased to 7,000 meters. Now if the receiver is tunedto the wave radiated by the transmitter when the key is closed (7,000 meters), thewave radiated, when the key is open (or when the key lever is up), will not beheard in the receiving telephone, hence the Morse characters are formed atthe sender and easily distinguished at the receiver. The wave radiated
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
