GB772560A - Improvements relating to electrode assemblies for electron discharge tubes - Google Patents

Abstract

772,560. Thermionic valves. SYLVANIA ELECTRIC PRODUCTS, Inc. April 19, 1955 [April 19, 1954], No. 11321/55. Class 39(1). A cathode is separated by insulating wafers from a grid on either side, the assembly being held together by ears on one grid being bent over the other grid. The assembly shown is of the stacked type, the cathode sleeve 10 being supported by its wire loops 16 between insulating wafers 52, 54. The grids 20, 22 on either side have upstanding ears at each corner, as at 26 and 28. The ears 28 are longer than the ears 26, and spaced a little more widely apart, so that in assembling the grids, cathode, and insulators 52, 54 together, the ears 26 lie just inside the ears 28, with their ends level. A further insulator 50 is placed on the stack, and then the ears 26, 28 conjointly bent over the upper insulator 50, and welded together ; thus these elements now form a complete unitary sub-assembly. The anodes 30, 32 are of channel section, each having end web portions 36, and a central platform 38 (forming the active anode area) of less height than the portions 36. Ears 42 on anode 32 are longer than the corresponding eats 40 on anode 30, so that the ends come level after assembly of the complete doubletriode, and are then welded together: The assembly is supported from pins passing through the alumina base 70; a cross-bar 74 welded to two of these pins is welded to the under side of platform 38 of anode 32. In a simplified form of the assembly, the insulators 50, 56 may be omitted. The insulator 54 then rests directly on the web portions 36 of the lower anode. The grid is of such a length that it is clear of the web portions, and is also spaced from the anode surface 38. A modified form of grid consisting of wires secured to a ceramic frame, Fig. 4 (not shown), may be used.