GB234965A - Improvements in and relating to apparatus for reception of wireless signals and the like - Google Patents

Abstract

234,965. Hale, G. W., and Radio Engineering Co., Ltd. April 30, 1924. Thermionic amplifiers and detectors.-A dual amplification radio receiving circuit comprises a high-frequency input coil b connected at its high-potential end to the primary coil e of an audio-frequency transformer, the secondary coil of which is connected to the grid of a backcoupled valve d. The other end of the primary coil is connected through a crystal or like detectors g to earth, and the other end of the secondary coil f is connected to the aerial end of the primary coil e. High-frequency oscillations are conveyed to the crystal and to the grid through the capacity of the coils e, f, whilst low-frequency currents arising in the coil e from the rectifying action of the crystal are stepped up to a higher voltage bv the transformer and also applied to the grid. The plate circuit of the valve includes telephones k, battery l, and a reaction coil h for increasing the oscillations of the aerial, which is tuned by a condenser a, the only tuning element in the circuit. Low-frequency electrical disturbances are eliminated, owing to the primary and secondary coils e, f being connected to each other and both in the grid circuit, neither of them being directly connected to earth. Stages of high-frequency or lowfrequency amplification may precede or follow the dual valve.