GB473452A - Improvements in the mounting of electrodes in electron discharge tubes - Google Patents

Abstract

473,452. Thermionic valves. STANDARD TELEPHONES & CABLES, Ltd. Dec. 18, 1936, No. 34852. Convention date, April 18. [Class 39 (i)] In a high power valve having a vitreous extension 5 to the main metal envelope part forming the anode 1 a conducting tube 9 passes through the re-entrant part of the extension and is sealed thereto by the metal cylinders 10, 12 ; mounted on the closed inner end of the tube 9 is a cylinder 14, Fig. 1 and 2, perforated for lightness and having integral flanges 16, 18, 23. By means of flange 23 the cylinder 14<1> is fixed to the tube 9. The flange is screwed to the sleeve 10 welded to the tube 9 ; the seal between the tube 9, sleeve 10 and re-entrant part of the vitreous envelope is effected by the part 12. The flange 16 has an attached ring 36 which holds the four grid rods 34; two shields 41 and 42 and a spacer 39 are placed on these rods, which also carry a holding plate 43 for the filament supports 69, the plate 43 being held between springs 44 on the grid rods 34. Surrounding the cylinder 14 are plates 26, 27 and a flange 20 prevented by a stud 19 from moving round the cylinder 14; the end flanges 16, 20 and plates 26, 27 are spaced apart by quartz or like insulators 25, a spring 21 keeping the flanges 16, 20 and plates 26, 27 in place. The plates 26, 27 form the supports for the two sets of filament rods 54, which carry screening spacers 57, 58. The plates 26, 27 have diametrically opposed extensions 28, 29 connected by bent rods 30 to flexible inleads 8; the tube 9 forms the lead to the grid. The filaments are attached to the rods and pass over rockers 63 held by stirrups 66 at the ends of the rods 69 ; these are subjected to the pressure of the springs 76 which bear on the platform 72 insulated from the abutment plate 43. Heat screens 79 act as spacers for the rods 69 and therefore for the filaments which are also relatively positioned by interconnecting pieces 65. The ends of the grid rods 34 are bent and fitted into a nut 45 which carries a three-legged insulator 51 bearing on the inside of the envelope ; one or more skirts 53 are formed on each part of the insulator. A screen 82 protects the joint between the anode and vitreous end 5. As an alternative arrangement the filaments may be directly supported from the tube 9, and the grids by the plates 26, 27, etc.; if more than three electrodes are to be used in the valve additional plates are employed.