Improvements in or relating to thermionic valve systems employing screen grid valves

摘要

398,157. Valve amplifying and detecting circuits. FILIPPONI, A. and SOC. ANON. NAZIONALE DEL GRAMMOFONO, 14, Via Domenichino, Milan, Italy. Dec. 3, 1931, No. 33570. Convention date, Jan. 14. Void [Published under Sect. 91 of the Acts]. [Class 40 (v).] The screen-grid circuit of a valve amplifier includes a coil Ls which may be back-coupled to the input circuit L for giving reaction or selfoscillation, or alternatively may be used as a coupling coil fed by a separate local oscillator for frequency-changing or heterodyne wireless receivers. The screen-grid voltage may be applied through the coil Ls, or as shown in the Figure, a choke coil J may be connected in the supply circuit, and the circuit of the coil Ls may include a variable condenser C for regulating reaction.