GB656524A - High frequency converters - Google Patents

Abstract

656,524. Valve receiving circuits. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 24, 1947, No. 25951. Convention date, Oct. 8, 1942. [Class 40 (v)] A high frequency converter comprises a triode, a resonant cavity associated with the grid and cathode, means for feeding the signal frequency and local frequency to the cavity, # the local frequency being (1Œ-) times the signal frequency where # is an odd integer and # an even integer, means for tuning the cavity to be resonant to both the signal frequency and the local frequency, and means for extracting the intermediate frequency from the anode. In Fig. 5 the cathode and grid of the lighthouse triode 6 are coupled respectively to the outer and inner conductors 4, 5 of a coaxial line. The line is tuned by plunger 44 to be resonant to both the signal and the local frequencies. This may be done by making its effective electrical length equal to where #s, # i are the wavelengths of the signal and local frequencies. The signal frequency is fed in by a transmission line 36, 37 to a probe 38 which is adjustable for matching purposes. The local frequency is fed in by a coupling loop 52. The anode of the valve is connected to the inner conductor 62 of a coaxial line, the outer conductor 5 of which is connected to the grid, which is tuned by a plunger to be resonant to the intermediate frequency. In a modification, Figs. 1 and 2 (not shown), this tuned line is omitted and the output is obtained direct from the anode. In Fig. 8 the grid-cathode line is replaced by a waveguide 69 provided with a tuning plunger 75 and an adjustable probe 93 which can be used to neutralise any reflections from the valve. The Specification as open to inspection under Sect. 91 also describes a modification of Fig. 8 using a diode instead of a triode. This subjectmatter does not appear in the Specification as accepted.