GB525826A - Improvements in or relating to radio and television receivers - Google Patents

Abstract

525,826. Wireless receiving systems. KOLSTER-BRANDES, Ltd., and SHANNON, D. S. B. Feb. 28, 1939, No. 6554. [Class 40 (v)] A substantially-aperiodic resistance-capacity-coupled intermediate-frequency amplifier is used for the different intermediate frequencies of television signals and ordinary broadcast programmes, said intermediatefrequencies having the usual values such as 10MC and 450kc, respectively. In the system shown, frequency-changers FC1, FC2 for the television with its accompanying sound and the broadcast programmes, respectively, feed into a common I.F. amplifier IF1, IF2 having resistancecapacity coupling and comprising valves of electron-multiplier type. The output of the stage IF2 includes series circuits L4, C4; L5, C5; L6, C6 tuned, respectively to the I.F. of the vision signals, the accompanying sound, and the broadcast programmes. The circuit L4, C4 transmits the vision signals through further amplifiers V6, V7' to a vision receiver. The circuits L5, C5 ; L6, C6 are connected up alternatively by a switch S2, the sound in either case being passed through a further I.F. stage IF3 to a detector V9. A further switch SI, ganged with S2, connects the high-tension source alternatively to the oscillator anodes of the frequency-changers FC1, FC2, according as television or ordinary broadcast programmes are being received. In a modification, Fig. 2 (not shown), a common frequency-changer is used, with switching means, ganged with S2, for changing over the input circuits and the localoscillator tuned circuits.