GB492610A - Improvements in or relating to high frequency oscillators - Google Patents

Abstract

492,610. Valve generating circuits; electric resonators. GENERAL ELECTRIC CO., Ltd., and MEGAW, E. C. S. March 22, 1937, No. 8367. [Classes 40 (iii) and 40 (v)] An oscillator, for example, a split-anode magnetron, particularly for generating very high frequencies, has a pair of electrodes connected to points on a resonator having capacity and inductance (which may be distributed) by a pair of leads the length of which is adjustable so that the system comprising electrodes, leads, and resonator may oscillate as a whole at the desired frequency. In one arrangement, Fig. 1 (Prov.), the resonator comprises parallel conductors 9, 10 having a fixed bridge 11 at one end and a movable bridge 12 to tune it to the desired frequency. The lengths of the leads 5, 6 are adjusted by telescopic members so that the points 7, 8 are at the first potential node, i.e. the electrical length of the leads is one-quarter of a wave-length. The production of harmonics may be prevented by connecting resistances shunted by small inductances in the leads 5, 6 close to the generator. The load circuit 13 is connected across the resonator by tappings 16, 17. In a modification, Fig. 2 (Prov.) (not shown), the bridge 11 is replaced by a variable condenser to the terminals of which the leads 5, 6 are permanently connected. In a third arrangement shown in Fig. 1 (Comp.), the resonator is of fixed frequency and comprises coaxial tubes 5, 6 connected at one end by a grounded plate 7. The magnetron comprises four anode sections connected together in pairs and to conductors 9, 10 having their lengths adjusted by a bridge 11 to threequarters of the wave-length of the fundamental frequency. One connection from a generator electrode to the resonator takes place through ground at 8 and on the cathode the other comprises part of conductor 10 and lead 13 to a point 14 on the inner tube and the length of this connection is adjustable by telescopic means or by varying point 12. This system oscillates at three times the fundamental frequency and the fundamental may be suppressed by connecting a choke across terminals 2, 3. The load may be connected to the resonator or to conductors 9, 10. The resonator tubes may be of copper or steel plated with silver, and suitable dimensions are given in the Specification. Specification 417,564 is referred to.