GB729443A - Combined television receiver and broadcast receiver - Google Patents

Abstract

729,443. Radio receiving sets. STANDARD TELEPHONES & CABLES, Ltd. Oct. 17, 1952 [Oct. 26, 1951], No. 26107/52. Class 40 (5). A radio receiver for receiving alternatively television signals with concomitant sound signals and V.H.F. sound broadcast signals, comprises means whereby, during television reception, the concomitant signals undergo two stages of frequency changing to reach a final intermediate frequency which is reached, during sound-broadcasting reception, by one stage of frequency changing. The incoming signals are amplified by an H.F. amplifier 1 which is adapted to be tuned to either the sound-broadcasting band or the television band and then undergo a stage of frequency changing in mixer 2. Oscillator 3 is a variable-frequency oscillator which may be tuned to effect the conversion of the incoming signals to predetermined intermediate frequency at the output of mixer 2; in the case of television reception this intermediate frequency is converted to a second intermediate frequency by mixer 5 and fixedfrequency oscillator 6 for amplification in the sound I.F. channel 7. In the case of sound broadcast reception the oscillator 6 is switched out of circuit by the switch 8 and the tuning of the oscillator 3 is arranged to provide the second intermediate frequency directly at the output of mixer 2. The Specification describes how the local-oscillator frequencies are chosen to avoid interference by harmonics thereof within the television and sound-broadcasting bands.