GB438362A - Improvement in ionic discharge device and circuit therefor - Google Patents

Abstract

438,362. Thermionic valves. ROBINSON, J. A., 171, East Mosholu Parkway, North, Bronx, New York, U.S.A. May 11, 1934, No. 14354. Convention date, March 23. [Class 39 (i)] In a vapour-filled discharge amplifier the grid wires are of not more than À003 inch diameter and adjacent grids are wound in opposite directions. As shown three grids are wound on pairs of support rods 26, 36, 27, 37 and 28, 38 which are themselves stayed by wide bands 6<a>, 7<a>, 8<a> at each end. The inner grid is maintained at a negative bias of 20 volts and has 33 turns per inch ; the intermediate grid has a positive bias of 49 volts and has 24 turns per inch ; the outer grid has a positive bias of 70 volts. The enclosing anode 9 has mica end cover plates 10, 11. A grid so constructed is particularly suitable for use in valves as described in Specifications 438,360, 438,961, and 439,879, the control by the inner grid being electronic despite the filling, which is a mixture of 75 per cent cadmium and 25 per cent mercury supplied from the getter mount 12.