GB439047A - Improvements in or relating to radio receivers - Google Patents

Abstract

439,047. Valve circuits for wireless reception. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, London, RUST, N. M., 109, London Road, and KEALL, O. E., 32, Rainsford Avenue, both in Chelmsford. May 28, 1934, No. 15877. [Class 40 (v)] In a reflex circuit arrangement, received oscillations are impressed on one grid of a multi-grid valve and after a change in frequency are fed back to another grid of the same valve for reamplification. In Fig. 1, the aerial input is applied to the grid G4 of a heptode V the anode circuit of which is coupled to a triode rectifier 7. The demodulated output from the valve 7 is applied to the inner grid G1 of the heptode V, the low-frequency output being taken from the grid G2. The heptode thus functions as a high - frequency tetrode and low - frequency triode amplifier. In the superheterodyne arrangement of Fig. 2, local oscillations from LO are injected in the anode circuit of the heptode V the output from the first detector 71 being fed back to the heptode inner grid G1, thence from G2 to the signal rectifier 13. In a modification, the frequency changer stage may be a radio frequency pentode, the output of which (at the intermediate frequency) is applied to a circuit such as Fig. 1, Fig. 3 (not shown) ; instead of the intermediate frequency, the audio frequency currents may be fed back to the heptode inner grid, Fig. 4 (not shown). The triode portion of the heptode V may constitute the signal rectifier, Fig. 6 (not shown). In all cases reaction may be obtained by back coupling the anode circuit of the heptode to the aerial as shown in Figs. - 1 and 2 ; the sense of the feed back to the inner grid is preferably chosen so that the modulation is opposed in phase to that of the highfrequency input, to give greater amplification with stability.