GB255441A - Improvements in electron discharge devices - Google Patents

Abstract

255,441. British Thomson-Houston Co., Ltd., (Assignees of Simonds, D. T.). July 20, 1925, [Convention date]. Addition to 230,011. Vacuum tubes.-In a valve having a screening grid extending beyond the ends of the control grid and anode according to the parent Specification, the screening grid is in the form of a cylinder with its ends closed by insulating members through which the leads for the cathode and control grid are taken; metallic shields are provided for eliminating the effect of capacity between the leads of the anode and control grid. As shown in Fig. 1, the screening grid 5, consisting of wire wound on rods, is mounted at one end on a metal cylinder 7 surrounding a reentrant tube 9, and at the other end has a metal cylinder 6 surrounding an insulating member 8 through which passes one lead for the cathode 2. The other cathode lead and the lead for the control grid 4 pass through the tube 9. A tubular metallic shield 19 extends into the tube 9 so as to overlap the cylinder 7. and has a depending member 20 surrounding the contacts 21, and fitting into a metal shell 22 connected with a metal plate 25 on the socket 23 which may be mounted on a metal panel 26. The shielding system thus formed is connected with earth. The anode 3 is supported by springs 15, and connected with a contact shell 18. In the arrangement shown m Fig. 2, the cylinders 6, 7 on the screening grid 5 are both mounted on re-entrant tubes 28, 29 respectively, and shields 37, 38 extend into the tubes, and surround the ends of the container. One of the cathode leads is connected with the member 37. which makes contact through springs 41 with a metal shell 36 surrounding the container and connected with a contact 21. The control grid 4 is connected with a contact 35 mounted on and insulated from the shell 36 at the opposite end of the container from that carrying the contacts for the anode and screening grid. The shell 36 is earthed.