GB524049A - Improvements relating to circuits for electron discharge devices employing secondary emission - Google Patents

Abstract

524,049. Electron multipliers and circuits therefor. KOLSTER-BRANDES, Ltd., SHANNON, D. S. B., and CHATTERJEA, P. K. Jan. 20, 1939, No. 2032. [Class 40 (v)] A frequency changing or high-frequency modulating circuit comprises an electron discharge device V having a control electrode G1, an accelerating or screening electrode G2, a secondary emitting electrode SE and an anode A, one of the two last-mentioned electrodes, namely the secondary emitter or the anode, being coupled back to the electrode G2 for the generation of oscillations to beat with signal waves applied to the control electrode G1, a tuned output circuit being connected to the other of the two electrodes SE, A. In the arrangement shown, the tuned input circuit L1, C1 is connected between the grid G1 and cathode C with biassing means R2, C2, and a tuned intermediate-frequency output circuit L3, C3 is connected in the anode lead. A tuned oscillator circuit L5, C5 is connected between SE and G2, an intermediate point in the oscillator circuit being earthed. Intermediate potentials are applied to the secondary emitter SE and screen grid G2 over decoupled potentiometer circuits R3, R4, C6 and R5, R6, C7. The valve then functions as a frequency changer for use in a superheterodyne radio receiver. In a modification, the anode is coupled to the screen grid over the oscillator circuit, and the intermediatefrequency circuit is connected in the lead to the secondary emitter. In either arrangement an additional tuned ciruit may be connected between the more positive oscillator electrode and ground ; this arrangement allows the oscillator to beat with two incoming signals of different frequencies, the respective intermediate frequencies being then taken from the tuned circuits in the anode and secondary emitter connections. Thus in the case of a television receiver, the sound-modulated intermediatefrequency carrier may be taken from one circuit and the vision-modulated intermediate-frequency carrier from the other. The invention may be applied to multi-stage electron multipliers, the secondary emitter immediately preceding the anode being then preferably used for the back coupling.