. Practical wireless telegraphy; a complete text book for students of radio communication . uum Valve as a Combined Detector, Amplifier and Beat Receiver. —Much of the record-breaking, long distance transtgission effected, of late, is due to thevacuum valve being employed as a combined detector and beat receiver. One circuit ofthis type is shown in Fig. 294, wherein it will be observed that the secondary circuit, 1^4,L-3, C-2 and L-S, can be placed in resonance with the tertiary circuit, L-6, L-7 and C-4and when the filament is brought to the correct degree of incandescence by the rheostat R^t
. Practical wireless telegraphy; a complete text book for students of radio communication . uum Valve as a Combined Detector, Amplifier and Beat Receiver. —Much of the record-breaking, long distance transtgission effected, of late, is due to thevacuum valve being employed as a combined detector and beat receiver. One circuit ofthis type is shown in Fig. 294, wherein it will be observed that the secondary circuit, 1^4,L-3, C-2 and L-S, can be placed in resonance with the tertiary circuit, L-6, L-7 and C-4and when the filament is brought to the correct degree of incandescence by the rheostat R^the discharge of condenser C-4 through L-7 and L-6 starts the flow of undamped oscilla-tions which are transferred to the secondary circuit through L-S and L-6. Due to the relaying action of the valve, the oscillations are repeated back to the grid(of the valve) through L-S and L-6 and accordingly amplified. Now if the antenna circuit, L-1, L-8 and L-2, is adjusted to the frequency of the incom-ing oscillations, and the secondary, as well as the tertiary circuit, adjusted to a slightly. VACUUM VALVE GENERATORFig. 293—^The Vacuum Valve Heterodyne Receiver. RECEIVERS FOR UNDAMPED OSCILLATIONS OR WAVES. 281 different frequency of oscillation, a beat current is set up in the secondary circuit, which isamplihed in the local telephone circuit by the charge placed upon the grid. As explained by Armstrong, the incoming oscillations are transferred from the antennacircuit to the secondary circuit in the usual manner, and due to the repeating action of thevalve, they are reproduced in the tertiary circuit, coupled back to the secondary circuitthrough the coupling transformer, L-5 and L-6, and re-enforced, all this taking place whilethe valve is generating oscillations locally. Simultaneously, beats are produced by theinteraction of the local oscillations and the incoming oscillations, the effect being to alter-nately increase and decrease the amplitude of the oscillations in the compl
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
