GB279576A - Improvements in or relating to thermionic valves - Google Patents

Abstract

279,576. Edison Swan Electric Co., Ltd., and Price, T., W. Aug. 11, 1926. Vacuum tubes.-To prevent bombardment of the envelope of high-power oscillator valves, which have an electron-emitting filamentary cathode and contain substantially no residual gas, by electrons from parts of the cathode not surrounded by the grid, these parts are substantially completely surrounded at one end by a thimble or cap b of metal gauze or foil and at the lower end by a screen b<1> of similar material and preferably of frusto-conical form, these screens being placed over the frame a of the grid m, and the enclosure is completed at the lewer end by a metal disc e attached to the molybdenum wire n which supports the bight of the filament. An insulating space h is left between the disc e and the grid frame. The filament support n is freely slidable in steatite blocks r secured to the filament leading- in wirss g, a spring o serving to keep the filament taut. The grid is supported by clamping- bands d embracing depending wires l. A glass sleeve i is placed over the filament stem j to strengthen the insulation between the filament and grid leads.