GB250748A - Improvements in or relating to receivers for high frequency electric signals - Google Patents

Abstract

250,748. Brown, W. J., Burch, C. R., and Metropolitan-Vickers Electrical Co., Ltd. March 31, 1925. Thermionic amplifiers and detectors.-Relates to circuits of the type in which a " trigged " amplifying valve is set into self-oscillation by a received signal, and is periodically quenched by means of locally-generated oscillations, and consists in applying to the plate of the amplifying valve a source of alternating potential only. Simultaneously the grid is supplied with an alternating potential substantially equal to the plate voltage divided by the voltage factor of the valve, the grid and plate potentials being in phase opposition. Fig. 2 shows an arrangement in which the output from the amplifying valve 12 is not quantitatively proportional to the received signal. The valve is set on the threshold point by adjusting the reaction coils 23. 15 and the steady grid bias from the potentiometer 19. The plate voltage is derived from an alternator 20, whilst a tapping taken from a resistance 26 supplies the requisite alternating voltage to the grid 11. Fig. 4 shows a taper-regenerative receiver giving ,a quantitative response, suitable for telephonic reception. The alternating potentials required to supply the plate and grid voltages of the trigged valve 12 are generated by a second valve 37, fed by a high-tension battery 35 and retroactively coupled across a tuned circuit 31, 32. A blocking condenser 42 and choke 41 ensures that only the high-frequency oscillations generated in the circuit 31, 32 reach the plate of the valve 12, whilst an adjustable tapping from the inductance 31 supplies an oscillatory voltage to the grid 11.