GB805399A - Improvements in electron discharge tubes - Google Patents

Abstract

805,399. Discharge tubes. MULLARD RADIO VALVE CO. Ltd. March 5, 1957 [March 29, 1956], No. 9935/56. Class 39(1). An indirectly heated cathode is mounted at one end of a thin-walled tubular member the other end of which is anchored to a supporting ring, and a second electrode is carried on a support secured to the exterior of the tubular member. In Fig. 1, the cathode 5, which has a rearward houisng for the heater 8, is mounted at one end of a tube 6 ; the tube may be of metal foil having relatively poor conductivity, such as nickel-iron alloy. Round the tube are welded semi-circular straps 10 having radial extensions at each end. Between each pair of extensions are held rods 11 which are united through glass beads 12 to further rods 13 positioned within sleeves 14, the sleeves carrying the grid structure 16. In assembling, the cathode-grid spacing can be adjusted before finally welding rods 11 and straps 10 together. The tube 6 may be thinner at the cathode end, and the other end may be slit longitudinally to form a number of tags which can be bent out at right-angles and secured to a supporting ring 7. The envelope 17 of the device has an anode and a locating plate secured by respective disc seals 19, 18. The assembly of Fig. 1 is introduced at the lower end of Fig. 2 so that the grid assembly abuts against the locating plate. The sleeves 14 pass through holes in this plate, and their ends are bent over by a tool passing through holes in the anode, thus locking the assembly in position.