GB824055A - Improvements in electron discharge devices - Google Patents

Abstract

824,055. Thermionic valves. MACHLETT LABORATORIES Inc. July 12, 1957 [Aug. 13, 1956], No. 22168/57. Class 39(1). In a discharge tube in which a low amplification factor, i.e. between 3 and 10, is required, the grid has a plurality of parallel wires which are also parallel to the anode and cathode, the wires being spaced apart sufficiently widely to produce a variable mu across the cathode, and the effectively emitting portions of the cathode are restricted to the areas thereof where the mu is relatively low. In the arrangement of Fig. 2, both grid and cathode are formed of a series of separate wires, respectively 18 and 33. The spacing between the grid wires is considerably greater than the grid-cathode spacing, so that a variable mu effect between adjacent grid wires is obtained, Figs. 4 and 5 (not shown). As shown, the cathode wires 33 are located midway between the grid wires, where the mu is at a minimum, there being no emissive portion in the higher mu areas adjacent the grid wires. In the alternative arrangement of Fig. 6, the cathode 38 has emissive strips 41 lying between and parallel to the grid wires 40. The completed tube may be constructed as in Fig. 1 (not shown.)