GB640267A - Improved signal-translating stage for radio signalling - Google Patents

Abstract

640,267. Valve circuits for radio reception. HAZELTINE CORPORATION. June 10, 1947, No. 15286. Convention date, June 22, 1946. [Class 40 (v)] In a high-frequency amplifier or a frequency-changing stage positive feedback is used to balance out the inherent input conductance of the valve and negative feedback to provide damping on the input circuit which is constant over a range of frequencies and does not increase the circuit noise. As applied to a triode frequency-changer positive feedback which varies with frequency in the same manner as the transit-time input impedance is produced by means of inductance 18 inserted in the anode lead, in conjunction with the anode-grid capacity 21. A constant input conductance is obtained by negative feedback, also over capacity 21, and provided by the intermediate-frequency transformer, which behaves as a capacity 17 at the signal frequency. The arrangement may be used, Fig. 2 (not shown), in an inductively-tuned constant band-width preselector circuit of the type described in Specification 535,078. In a modified arrangement using a pentode or hexode valve, Fig. 3 (not shown), feedback is obtained over the screen to grid capacity from the screen circuit, which comprises inductance and capacity in series, the steady screen potential being applied over a choke. U.S.A. Specification 2,279,543 is referred to.