GB440483A - Improvements in or relating to radio receivers - Google Patents

Abstract

440,483. Valve circuits for wireless reception. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE, 12, Hallesches Ufer, Berlin. May 30, 1934, Nos. 16188 and 16189. Convention dates, May 30, 1933 and Aug. 17, 1933. [Class 40 (v)] The grid of a high-frequency amplifying valve 1 is, in the absence of signals, positively biassed by a battery B through the resistances R, R <1> and the tuned circuit L, C, the latter being damped by the flow of grid current and hence of small amplification. Signals are applied to the circuit L, C and a circuit L<1>, C<1>, the latter feeding a diode rectifier 2 with load resistance R which produces a delay voltage on the anode of the diode due to the flow of the grid current therethrough. As the signal strength increases, the D.C. potential developed across R opposes that due to the battery B and the amplification of the valve 1 rises until its grid begins to become increasingly negative for the purpose of automatic volume control. The normal muting action may be counteracted by opposing the grid bias due to the battery B with a potential due to a cathode resistance R<111> which is normally short-circuited by a switch D. The switch D may be coupled to a wave-change switch so that the muting is ineffective on short waves.