GB1226582A - - Google Patents

Abstract

1,226,582. Thermionic cathode tubes. MACHLETT LABORATORIES Inc. 30 Aug., 1968 [1 Sept., 1967], No. 41642/68. Heading H1D. A filamentary cathode structure, e.g. for a high power tube, includes a filamentary cathode, e.g. 57, which has one end fixed to an elongated member 48 arranged to apply tension to the cathode, the elongated member 48 extending through a supporting frame, e.g. 97, between a pair of opposing resilient arm-like members 100, 101, Fig. 8, each having one end fixedly supported by the frame and its opposite end engaged with the elongated member 48. As shown in Fig. 1, cathode filaments 57, 58, 59 and 76, 77, 78 are secured at one end to cross-arm 34 supported from centre post 32 and at the other end to respective support rods 48, 49, 50 and 68, 69, 70 which are mounted under tension by springs 85 from support deck 39. Each cathode 76-78 in a set mounted on one side of the centre post 32 is connected to the same cathode terminal 61 via the support rods 68-70, deck 39, posts 62a and support disc 62, whilst the remaining cathodes 57-59 in the other set are connected to cathode terminal 41 via the support rods 48- 50, straps 45-47, post 43 and support disc 42 and are insulated from deck 39 by dielectric bushings 51. Each support rod has two spaced peripheral grooves 83, 84 and the rods of each set are mounted in respective support boxes 52, 72 which include two metal plates 97, 98 mounted perpendicularly to the support rods. As shown in Fig. 8, metal plates 97, 98 comprise a sheet-metal square with H-shaped slots 99 cut therein to form pairs of opposing resilient cantilever arms 100, 101 and when mounted therein the grooves 83, 84 of the support rod are engaged by arcuate portions 105 on opposing edges of the cantilever arms. The cantilever arms are able to flex, Figs. 9, 10 (not shown) as the filaments expand or contract and so allow them to move longitudinally and be maintained under tension by springs 85 whilst still preventing any sideways movement. Two parallel rows of grid wires 25 may be mounted either side of the line of cathodes and the anode 10 may have a corresponding flat parallel portion, Fig. 2 (not shown).