GB253192A - Improvements in and relating to receivers for wireless telegraphy and telephony - Google Patents

Abstract

253,192. Seymour, C., and Drabble, J. C. W. March 10, 1925. Thermionic amplifiers and detectors for the reception of wireless telegraphy and telephony, of the kind in which a back-coupled valve is trigged into oscillation by the received signals and is immediately quenched again, employ a single triode valve V1 with the receiving circuit connected between plate and grid, the condenser C2 dividing the two inductance coils L1, L2 of this circuit being also included in a quenching circuit of lower frequency. The quenching circuit comprises the fixed condenser C2, two coils L3, L4, another condenser C3 and a variable resistance R1 by which the amplitude of the oscillations generated by the valve in the quenching circuit can be regulated. The resistance R1 may be shunted across one of the coils L3, L4. The receiving circuit C1, C2, L1, L2 may be a frame aerial, or may be coupled to an extended aerial A. The receiving circuit may be tuned by varying the inductances L1, L2 instead of the capacity C1. A grid condenser C4 and leak resistance R2 are employed in the grid circuit, and the telephones T or other indicator or transformer are in the plate circuit. The quenching oscillations may be of sub-audible, audible, or higher frequency, but in receiving interrupted continuous waves, the frequency should be higher than that of the interruptions. The only adjustments required for correct working are the tuning of the receiving circuit, and regulation of the quenching amplitude. Specification 244,568 is referred to.