GB224817A - Improvements in or relating to systems of receiving and indirectly amplifying radio frequency electrical oscillatory energy - Google Patents

Abstract

224,817. Jackson, W. J. Mellersh-, (Westinghouse Electric & Manufacturing Co.). May 2, 1924. Heterodyne receiving systems; thermionic heterodyne receivers.-Relates to self-heterodyne receiving systems in which supersonic beats are employed, as in Specification 137,271, and consists in using an harmonic of the local frequency for beating with the incoming oscillations. The self-heterodyne valve 8 has two tuned circuitsconnected to its grid, one circuit 4, 12 being tuned to the incoming wave and coupled to the aerial 1, the other circuit 13, 14 being coupled to a coil 15- in the plate circuit and tuned to a much lower frequency so that the second or higher harmonicdiffers from the received frequency by a readilyamplifiable supersonic frequency. Owing to the considerable difference in frequency between the two grid circuits their reaction on each other is reduced, and the local energy is not radiated. The supersonic beats are selected by a tuned plate circuit 18, 19 and are transferred through amplifiers 22 to a detector 23, the speech or other modulation of the..received waves being audible in the telephone 24 in the detector output circuit. When receiving unmodulated continuous waves, the supersonic currents after amplification are transferred to a self-heterodyne valve operating in the same manner as the valve 8, to produce audible beats in a telephone in its plate circuit. Further heterodyne stages may be employed.