GB472351A - Improvements in or relating to radio and like apparatus - Google Patents

Abstract

472,351. Electric resonators. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Aug. 6, 1936, No. 21718. Convention date, Aug. 29, 1935. [Classes 40 (iii) and 40 (v)] An ultra-high-frequency oscillating or receiving valve is enclosed in a resonator of the tank type having adjustable capacity. The set may be sealed so as to be weatherproof and suitable for use on aircraft and other vehicles. In a Hartley oscillator, Fig. 1, a spherical copper resonator 23 encloses a single valve 17, and adjustable capacity is afforded by two metallic cylinders 3, 5, which are adjustably held in a tube 1 made of glass such as that known under the Registered Trade Mark " Pyrex. " The valve electrodes are connected to metallic bands 7, 9 which provide a capacitive coupling with the cylinders 3, 5. The tank may be cylindrical and the capacitive bands 7, 9 may be of unequal breadth, Fig. 2 (not shown). A pair of push-pull valves may be used, and the leads to the heater may be coaxial cylinders which constitute an adjustably tuned coupling,. Fig. 3 (not shown). The circuit may be of the push-pull Hartley type, Fig. 4 (not shown), the grids and plates of two valves being connected to four bands similar to 7, 9, while the plates are connected by a coil with a centre tapping for connection to the battery. In a modification, Fig. 5, having set-screw-adjustable capacity 303, 305, the grid and plate are connected to capacitive insulated plates 311, 313, situated near the equator E of the resonator, which is a current antinode, for the purpose of improving frequency-stability. Aerials. Aerials 35, 37, Fig. 1, of length equal to a quarter of a wavelength, are attached to the tank resonator at points chosen with reference to the wavelength and to the resulting impedance.