GB720760A - Improvements in or relating to radio receiver circuits for at least two ultra high-frequency ranges - Google Patents

Abstract

720,760. Valve circuits for radio reception. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Feb. 27, 1953 [March 3, 1952], No. 5537/53. Class 40 (5). In a superheterodyne receiver operating on two ultra-high frequency ranges, the valve used for frequency-changing on the lower frequency range is switched to operate as an intermediate-frequency amplifier on the higherfrequency range, a crystal or diode mixer being used on this range. In one embodiment, Fig. 2, on the lower-frequency range signals from aerial 5 are amplified in a grounded-grid stage 16 and pass via coupled circuits 3, 4 to a triode mixer 8. Local oscillations from the oscillator 1 are also applied to the grid of the valve 8, the LF. output being taken from an anode coil 9 tuned by circuit capacity. On the higher frequency range, i.e. switch 17 moved to the left, signals are picked up on an aerial 15 tuned by a Lecher system 14, and are applied directly to a crystal mixer 12. A harmonic of the local oscillator frequency is used for mixing, being applied to the crystal 12 via a filter 11. On this range, the valves 16, 8 comprise respectively a grounded cathode and grounded grid stage operating at intermediate frequency, being coupled together by inductance 18 which is tuned by circuit capacity. In another embodiment, Fig. I (not shown), a pentode R.F. amplifier is used on the lower frequency range and is inoperative on the higher range; on this range I.F. signals are fed directly from the crystal mixer to the cathode of the triode mixer of the lower frequency range, which operates on the higher range as a grounded grid I.F. amplifier.