GB401305A - Improvements in or relating to thermionic valves - Google Patents

Abstract

401,305. Thermionic valves. WARREN, S. F., 27, Lowick Road, Harrow, Middlesex. May 2, 1932, No. 12643. [Class 39 (i).] A valve has a cathode, such as an equipotential cathode 2, surrounded by a control grid 3, a screening grid 5, an anode 4, and an external screening electrode 6, which is insulated from the screening grid and spaced laterally from one or more of the other electrodes at one or both ends, by an insulating member such as a glass bead or mica disc 11, which engages with the external screening electrode or with a support therefor, and with the other electrodes so that longitudinal movement of the electrodes is possible. The mica disc 11 is secured by metal clips 14 to a flanged metal disc 12 welded. to the electrode 6. The upper ends of the electrodes 2, 3, 5 pass freely through the mica disc 11. The metal disc 12 has a central aperture to prevent contact with the electrodes 2, 3, 5. A similar mica disc and metal disc may be secured to the other end of the electrode 6, or the electrodes 2, 3, 5 may be spaced by a mica disc 16 secured to a metal cap 15 attached to the screening grid 5. The electrode 6 may be insulated from all the other electrodes, but is preferably connected with a point of low potential such as the cathode, or earthed. The metal disc 12 may be connected with the screening grid 5 and insulated from the electrode 6. The anode may be of perforated metal or of grid form. A similar construction may be applied to a pentode in which the external screening electrode is connected with a suppressor grid by an annular plate as described in Specification 401,296.