GB440094A - Improvements in or relating to electron emitters for electron discharge devices - Google Patents

Abstract

440,094. Thermionic valves. STANDARD TELEPHONES & CABLES, Ltd., 63, Aldwych, London.-(Assignees of Veazie, E. A. ; 5, East 9th Street, New York, U.S.A.) July 27, 1935, No. 21386. Convention date, Sept. 5, 1934. [Class 39 (i)] In a valve intended for use at such high frequencies that it is necessary to separate the leads to the electrodes as widely as possible, the indirectly-heated cathode comprises a coated carrier member surrounding a metal support to which it is connected and a heater between the metal support and the carrier member. In one form, Fig. 3, a coated sleeve 26 is crimped at 27 round the end of a support 25 which carries an insulating tube 29 of beryllium oxide and a double helical heater 30. In a modification the tube 29 is dispensed with and the heater and the inside of the sleeve 26 are coated with insulation. The lower end of the sleeve 26 may be connected to the support 25 by a short thin wire. The cathode may be supported in a pentode 10, Fig. 1, by a rod 32 secured to the support 25 and to one of a pair of rods 16 carrying upper and lower shields 14, 15, and having a lead 13. A control grid 22, wound on a post 23, a screengrid 20 on posts 19, a suppressor grid 17 on the posts 16 and an anode 11 on a lead and support 12 surround the cathode. The posts are secured in an insulating disc 18. Leads are provided for the heater at 31, for the control grid at 23 and for the screen grid at 21. All or some of the turns of the grids 17 and 20 may be welded to the posts 16 and 19 respectively.