. The A B C of vacuum tubes in radio reception; an elementary and practical book on the theory and operation of vacuum tubes as detectors and amplifiers. Explains non-mathematically the fundamental principles upon which all vacuum tube circuits are based. Includes practical circuits and practical questions and answers. It is written especially for the beginner. All electrical and radio terms are fully explained . y Equal Grid? PotentialVariations Fig. 29 (a)—Amplification of continuous oscillations. These amplitudes in turn depend upon the amplitudes of theaudio-frequency plate current variati
. The A B C of vacuum tubes in radio reception; an elementary and practical book on the theory and operation of vacuum tubes as detectors and amplifiers. Explains non-mathematically the fundamental principles upon which all vacuum tube circuits are based. Includes practical circuits and practical questions and answers. It is written especially for the beginner. All electrical and radio terms are fully explained . y Equal Grid? PotentialVariations Fig. 29 (a)—Amplification of continuous oscillations. These amplitudes in turn depend upon the amplitudes of theaudio-frequency plate current variations passing through thereceiver magnet-coils. The coils smooth out the variationssomewhat, but their amplitudes depend nevertheless upon theamplitudes of the oscillations in the antenna circuit. Becauseof inherent amplification these audio-frequency current ampli- 78 A B C OF VACUUM TUBES tudes in the plate circuit are usually larger than those in theantenna. They may not, however, be large enough to create the. Damped6 rid PofenfiafVariations Fig. 29 (b)—Amplification of damped oscillations. desired amplitudes of sound waves and therefore the volume ofsound from the telephone receiver. Amplification must thenbe increased in some manner. VACUUM TUBE AMPLIFIER 79 Amplification Factor It has been stated that if the filament current and plate po-tential are kept constant, the plate current varies with the gridpotential. It is also true that if both filament current and gridpotential are kept constant, the plate current varies with theplate potential. There are then two possible ways to vary theplate current when the filament current is constant. But thereason the potential variations due to signals are applied to thegrid rather than to the plate is that they have greater effect uponthe plate current in the former case than in the latter. Therewould otherwise be no object in having a grid electrode. Theratio of plate potential variation to grid potential variation re-quired to
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