GB281391A - Improvements in devices for changing the frequency of electric currents - Google Patents

Abstract

281,391. Howe, A. B. Sept. 1, 1926. Thermionic valve circuits. - A frequencychanging circuit comprises a thermionic rectifying-valve V2 with a grid s maintained at a fixed positive potential relative to the filament and adapted to distort input electric oscillations so as to produce oscillations of higher frequency. The grid is maintained at such a potential that the rectifying-valve has a substantially linear characteristic over the working range. As shown two rectifying-valves are used arranged for pushpull rectification. The transformer L5, L2 following the rectifying valve is tuned by a condenser C2 and the circuit L5, C2 has an impedance rather less than the rectifying valve to ensure sharp tuning. According to modifications only one rectifying valve is used, and the primary of the following transformer is untuned (Fig. 1 not shown); the rectifying-valve is choke-capacity coupled to the preceding valve V1 (Fig. 2 not shown); auto-transformer coupling is employed between the rectifying-valve and the following valve V3 (Fig. 3 not shown); a high-frequency choke is inserted in the plate circuit of the rectifying valve and the following transformer is connected to the plate through a condenser (Fig. 5, not shown).