GB567585A - Improvements in or relating to electron discharge valve oscillators - Google Patents

Abstract

567,585. Automatic control systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. June 19, 1943, No. 9913. Convention date, June 19, 1942. [Class 38 (iv)] [Also in Group XL] Oscillation frequency.-A single valve circuit operates as an oscillation generator and as a thermionic reactance for controlling the resonant frequency of the tuned circuit, by connecting the circuit in feed-back relation with the screen grid, control grid and cathode of the valve, and by also feeding back energy to the circuit from the anode through a phasing reactance, the operating voltage on the anode being controllable to vary the resonant frequency. The circuit may be employed for the remote control or the automatic tuning of the local oscillator in a superheterodyne radio receiver. As shown, a tetrode valve V has its cathode, inner grid and outer grid associated with the tuned circuit L1, Cl in Hartley circuit arrangement. The valve anode 14 is connected through a resistance R3 or other load to a tapping on a supply potentiometer R4, and is connected to the control grid end of the circuit L1, C1 through a phasing reactance C3 producing a quadrature voltage component on the grid, and therefore affecting the oscillation frequency. The amplitude of this quadrature voltage is dependent on the anode voltage, and is controlled by varying the D.C. voltage applied across the condenser C5. This control voltage may be derived from a manual control at a remote point, or from an automatic tuning discriminator. Two valves may be associated with the tuned circuit L1, C1 in push-pull connection, Fig. 4 (not shown).