GB630710A - Improvements in or relating to magnetrons - Google Patents

Abstract

630,710. Magnetrons. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Feb. 20, 1947, No. 5004. Convention date, Nov. 4, 1944. [Class 39 (i)] A cavity magnetron, of the type provided with anode straps, has means whereby the capacity or capacities between the straps may be varied in order to tune the magnetron. Fig. 3 shows part of a cross-section of a magnetron with a grid 26 surrounding one end of the cathode 14 : this is used to control the number of electrons entering the space between the anode straps 23, 23a and hence the capacity between the straps. Fig. 6 shows a magnetron with straps in the form of cylinders 32 and the capacity between them is varied by insertion of a member 34, which is preferably a dielectric but may be a conductor. Movement of 34 is controlled by a knob 39, rotation of which causes the bellows 37 to contract or expand. In a modification using two cylindrical straps, Fig. 8 (not shown), auxiliary cathodes surrounded by grids are mounted on the. anode segments between the straps. Fig. 9 shows a magnetron using two series of straps 42, each strap connecting two segments. Dielectric members 46 are provided for varying the capacity and may be mounted on a ring 47 in the end space ; the ring 47 may be rotated by a lever 48 which is connected to the outside by a suitable vacuum sealing. In a modification the dielectric members are not used and the straps 42, Fig. 11, carry filaments 51 mounted on insulators 49. The temperature of the filaments controls their electron emission and hence the capacity between the straps. The Specification as open to inspection under Sect. 91 describes a further modification, similar to that shown in Fig. 6, wherein the magnetron has only one strap at the top, the other being at the bottom, and its capacity to earth is varied by moving a metallic plunger in and out. This subject-matter does not appear in the Specification as accepted.