GB175402A - Improvements in and relating to transmission circuits for wireless telegraphy and telephony - Google Patents

Abstract

175,402. Macrorie, A. K., Airey, H. Morris-, and Shearing, G. Nov. 15, 1920. Thermionic oscillation generators; harmonics, absorbing.-In order to eliminate harmonics from an aerial directly excited by a valve oscillation generator, a resistance and an inductance coil are connected in series between one of the main electrodes and the aerial inductance tapping, and one or more tuned circuits designed to by-pass the harmonics are connected between the other main electrode and the junction of the inductance and resistance. As shown in Fig. 1, the plate of the valve generator V is connected to the tapping point K of the aerial inductance L through a capacity C1, inductance L1, and resistance R, and a shunt, comprising inductance L2 and capacity C2 in parallel, is connected between the earthed filament and the junction point R, L,. The inductance-capacity products L, C1 and L2 C2 are made equal to the product LC for the aerial. The shunt L2 C2 allows harmonics to pass but offers high impedance to the fundamental oscillations. The resistance R prevents subsidiary oscillations from being set up in the circuits LKRC2, or CKRC2. The circuit L2 C3 may be replaced by one or more branches, each comprising inductance and capacity in series, and each tuned to an harmonic. The elements R, L1, C1 may be connected in the filament lead instead of in the plate lead. The grid circuit may be coupled inductively or directly to the aerial inductance.