. (The) oscillation valve in the transmission and reception of radio messages . It f^^ Microjpi^r^A Common. -f This method, though simple, is not effective.® Iftwo tubes instead of one are used, modulation can be effectedeasily by the so called absorbtion method. The tube usedas a generator of radio frequency oscillations is shuntedby a second tube which acts as an absorber. The extent ofthe absorbtion varies at audio frequencies in accordance with i the form of the speech impressed upon the mfbroiphone. Fig. L€ shows a circuit utilizing two tubes in this The piste circuit of tube A is p
. (The) oscillation valve in the transmission and reception of radio messages . It f^^ Microjpi^r^A Common. -f This method, though simple, is not effective.® Iftwo tubes instead of one are used, modulation can be effectedeasily by the so called absorbtion method. The tube usedas a generator of radio frequency oscillations is shuntedby a second tube which acts as an absorber. The extent ofthe absorbtion varies at audio frequencies in accordance with i the form of the speech impressed upon the mfbroiphone. Fig. L€ shows a circuit utilizing two tubes in this The piste circuit of tube A is parallel with theplate circuit of the generator tube B. The same radiofrequency voltage exists across the plate circuits of theabsorber tube and the generator tube. Since there is nocorresponding radio frequency voltage on the grid of theabsorber tube A, the absorber tube consumes radio frequencypower from the output of the generator tube. The ^amount ofpower absorbed by this tube is varied at speech frequencyby varying the grid voltage of A by use of a inductance LI must be a choke-coil of high impedanceto currents of radio frequency. This method, while simple,is not efficient. The most common method of tube modulation is thevarying of the input plate power. The variations in antennacurrent are more nearly proportional to^he variations inthe microphone current in this system, ^he above system,however, is not used much in practice, mostly because thereif a large drop in voltage across the modulative or absorbing**tube which must be compens
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Keywords: ., bookcentury1900, bookdecade1920, bookidtheoscillati, bookyear1922
