GB566364A - Power tube structure - Google Patents

Abstract

566,364. Thermionic valves. STANDARD TELEPHONES & CABLES, Ltd. June 4, 1943, No. 8996. Convention date, June 6, 1942. [Class 39 (i)] The cathode of a high-power vacuum tube comprises a number of quadrifilar - wound helical filamentary units placed end to end and supplied in parallel, the filaments of each unit being so connected, at one end to a common point and at the other end in parallel, that current flows in opposite directions in adjacent turns. In one form, two units 46 ... 49 and 51 ... 54, Figs. 3, 4, are connected in parallel to supply leads 44, 45, filaments 46, 48, 52, 54 being connected to lead 44 and filaments 47, 49, 51, 53 to lead 45. At their other ends the filaments of each unit are all connected to metallic discs 41, 43 forming common points so that, for example, filaments 46, 47 are in series. A similar disc 42 is placed between the units and discs 41, 42, 43 are rigidly supported by a rod 40. Leads 44, 45 pass insulatedly through discs 41, 42. In a modification, there are four units placed end to end, disc 43 acting as common point for two adjacent units. There may be only three units. Separate supply leads to each unit may be connected in parallel at the lower end. The cathode is surrounded by a grid 11, Fig. 1, and an anode 12 cooled by a double layer of water pipes 14, 15 making contact with it at raised portions 13. In a modification, a double layer of square pipes may make contact with a smooth outer anode surface.