GB594701A - Tuned electrical circuits - Google Patents

Abstract

594,701. Coil-less resonators; valve generating circuits. MARCONI'S WIRELESS TELEGRAPH; CO., Ltd. Oct. 16, 1944, No. 20005. Convention date, Aug. 26, 1941. [Classes 40 (iii) and 40 (v)] A coaxial resonator has an extensible inner conductor 21 or 22 and an outer conductor so shaped at 43 or 44 as to provide a linear frequency scale. Two such resonators may be connected to a valve, in the manner shown, so as to form a Hartley oscillator. The inner conductors then comprise rods 21, 22, surrounded by sleeves 30, 30<1> having contact springs 31, 31<1> and provided with threads which engage fixed nuts 9, 9<1> and floating nuts 11, 11<1>, the latter being constrained against rotation by pins 36, 36<1> and vertical slots, and having springs 35, 35<1> to take up backlash- Tuning is effected by turning the rods by means of a knob 13 through gear-wheels which may be dividedand sprung to prevent back lash, and the frequency is indicated by pointers 18, 18<1> and scales. The envelope 32 has trumpet-shaped extensions 43, 44, preferably closed by plates 8, 8<1>, and so shaped as to make the tuning scale linear. Change of frequency with temperature may be reduced by forming the resonators of suitably chosen metals, or a temperature-controlled enclosure may be used. The resonators are so connected to the valve 25 as to form a Hartley oscihator. The leads 26, 28 may be shielded, and for that purpose may pass inside the rods 21, 22 if these are hollow.