GB315375A - Improvements relating to electron discharge devices - Google Patents

Abstract

315,375. Westinghouse Lamp Co., (Assignees of Marden, J. W., and Lederer, E. A.). July 12, 1928, [Convention date]. Vacuum tubes. - In a discharge tube having an indirectly-heated cathode and a perforated anode, which facilitates the escape of heat and prevents the heating of the control electrode to a temperature at which it would emit electrons, the cathode-heater, which may be energized by alternating current, is connected at its ends, by means of connecting wires, to lead-in wires at the same end of the tube, one of said connecting wires being located outside of the anode and screened therefrom, to prevent hum, solely by a barrier of insulating material. In one example, Fig. 1, the cathode comprises a hollow metal shell 15, which has a coating of a mixture of the oxides of barium and strontium or a layer of caesium which is held thereon by an interposed atomic layer of oxygen or oxidized metal. The ends of the shell are closed by insulating plugs 17. The heating element consists of a coiled tungsten filament 21 supported by wires 19, 20 which are extended beyond the plugs 17 inside the shell in order that they may not attain a high temperature within the plugs. Current is supplied to the filament through wires 22, 23 which are connected respectively to a heavy wire 24 which supports the lower plug, and a wire 25 which is bent to secure an insulating porcelain or mica shield 26a in position. The wire 23 is encased in a glass tube. An anode 14 is perforated or former of wire mesh. A getter 33 may be provided on a carrier 34 which is supported by a wire 35 secured to a conductor 32. In a modification, Fig. 2, the electrodes are mounted between two insulators 36, 37 which have tubular portions 40, 41 securing the cathode. The insulators may be secured by means of members 54 welded to the supports 38, 39, which, alternatively, may be provided with enlarged portions as a securing means. Specifications 307,856 and 307,857 are referred to.