GB415060A - Improvements in or relating to modulated carrier wave receivers, particularly for radio receivers - Google Patents

Abstract

415,060. Valve circuits for wireless reception. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, and LINSELL, A. A., 43, West Hill, Sydenham, both in London. Feb. 15, 1933, No. 4659. [Class 40 (v).] In a supersonic heterodyne receiver gain control is accomplished by controlling the frequency of the local oscillator in dependence on received signal strength. In the embodiment shown, the receiver comprises aerial 1, high frequency amplifier 2, first detector 3, intermediate frequency amplifier and second detector 5 and oscillator valves 9, 10. The valves 9, 10 whose anodes are connected together and to a coil 23 coupled to the first detector, have frequency determining circuits 19, 21 respectively connected in their grid circuits and tuned slightly above and below the intermediate frequency to which the circuits 5 are tuned. The frequency generated by the combination 9, 10 is varied by altering the current flowing through a resistance 17 common to the grid circuits and supplied with the smoothed current from a rectifier 14 fed from a tuned circuit 13, 13<c>, coupled to the high frequency amplifier. In a modification said smoothed current is fed to a galvanometer mechanically coupled to a condenser which determines the frequency of the locally generated oscillations.