GB466686A - Improvements in or relating to radio and other high frequency circuit arrangements - Google Patents

Abstract

466,686. Valve generating and amplifying circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. June 9, 1936, No. 16137. Convention date, June 15, 1935. [Classes 40 (iii) and 40 (v)] A high frequency generating or amplifying circuit comprises a valve having input and output circuits comprising resonant tubular transmission lines arranged concentrically. The input and output circuits may each consist of two of a set of 4 tubular cylinders, Fig. 2 (not shown), or three cylinders may be used as in Fig. 3, the inner and outer surface of the middle cylinder 60 forming parts of different circuits. The cylinders may be tuned by adjustable telescopic portions and are of substantially t wave-length. The grid and plate connections are taken to intermediate points on the tubes to match the input and output impedances of the valve. A set of tubes may be connected with a. pair of valves in push-pull for generating or amplifying and the receiving circuit, Fig. 6, comprises two such amplifying stages followed by a push-pull frequency changer the input circuit of which comprises a tubular line 226, 228 of a length suitable for the local frequency, the output circuit 230 being tuned to the beat frequency. The electrodes of each pair of push-pull valves are symmetrically connected to the tubes. In a modified receiver, Fig. 5 (not shown) a single valve high frequency amplifier is followed by a single valve freqeuncy changer having tubular resonators for both grid and plate circuits, an ordinary output circuit tuned to the beat frequency being provided. The local frequency may be higher or lower than the received frequency. In the modified oscillator shown in Fig. 7, the tubular members have enlarged ends as shown and an additional (outer) tube is provided to furnish, with the outer surface of the next tube, a feed back circuit. Alternatively, the tube 702 may be extended downwardly, as shown in dotted lines, for the feed back circuit, the outer tube being also extended to form a screen. In a further arrangement, Fig. 8, the inherent feed-back is neutralized by condenser 830 and feed-back is then adjusted by condenser 834, or condenser 830 or 836 may alone be used to adjust the feed back. Arrangements in which the valve is mounted within the inner tube and in which the complete circuit is contained in a thermostatically controlled oven to avoid temperature variations are described with reference to Figs. 9 and 10 (not shown), which however show ordinary tuned circuits for the outputs.