GB412643A - Improvements in gas or vapor filled electric discharge devices - Google Patents

Abstract

412,643. Thermionic valves. RADIO RESEARCH LABORATORIES, Inc., 597, Madison Avenue, New York, U.S.A. Jan. 9, 1933, No. 763. Convention date, May 3, 1932. [Class 39 (i).] A gas or vapour filled device comprises a thermionic cathode, a foraminous control grid and an anode mounted between a pair of insulating blocks on support wires passing through the blocks, so that the ends of the control grid are completely closed by the blocks. In one form, Fig. 1, an indirectly heated cathode 1 is surrounded by a helical grid 3 and a sheet or mesh anode 5 and a pair of insulators 11, 15 is arranged to close the ends of the control grid and the anode. The anode voltage during operation is greater than the ionizing potential of the filling. The cap 17 may be of metal and may be secured to the envelope by a metallic current for the purpose of conducting heat away from the envelope. For a given gas pressure the grid openings are such that the reaction between anode and grid is in the opposite phase to that necessary to cause sustained oscillations, for example with a pressure of 0À1 mm. the openings are of the order of 0.02 inches. A circuit is described in which the grid is biassed so that the valve operates on a negative portion of the grid voltage-grid current characteristic. The theory and mode of operation of the valve are described in detail.