GB516168A - Improvements in electron discharge tubes - Google Patents

Abstract

516,168. Thermionic valves. DEHN, F. B. (Hygrade Sylvania Corporation). May 17, 1938, No. 17176/39. Divided out of 516,110, and 516,111, under which a Specification was laid open to inspection under Sect. 91 of the Acts, Nov. 29, 1938. [Class 39 (i)] The envelope 31 of a thermionic valve is closed at its lower end by a flat header 32 of insulating material such as glass through which are sealed a number of rigid contact pins 39, and encloses an electrode assembly including an indirectly heated cathode, and an insulating bridge 115 is supported on the inside of the header and carries metal tabs 119 for the purpose of connecting the ends of the fine filamentary cathode heater to its contact pins. In the arrangement described, the electrode assembly comprises an indirectly heated cathode, control, screening and suppressor grids and an anode, mounted between mica discs 45, 46 and completely enclosed in a metal shield consisting of a cylinder 66a with end closure discs 66b, 49. The shielding effect is continued exteriorly of the envelope by a metal cap 70 which overlaps the lower edge of the interior shield, and has openings for the passage of the contact pins and a central tubular extension 75 with a locating rib 76 adapted to contact with a grounded socket. On the inside of the header is disposed a metal disc 110 wlich is surrounded by the contect prongs and carries channel members 113 adapted to shield the anode and control grid pins from each other. The bridging member 115 is mounted in slots in the channel members 113. The exhaust tubulation 44 passes through a central hole in the disc 110 and is protected by the tubular metal extension of the cap 70. A getter cup or carrier 66d is supported centrally above the mount by a wire 66e welded to the internal shielding member. Specifications 516,110, 516,111, and 516,167, are referred to.