GB225899A - Improvements in or relating to thermionic valves or the like - Google Patents

Abstract

225,899. Lea, N., and Radio Communication Co., Ltd. July 12, 1923. V a c u u m tubes. - Resistance is incorporated in a valve or other discharge tube of such a value as to reduce the tendency to self-oscillation. One or more electrodes or their leads may be made of resistance material or a separate resistance may be mounted in the valve. As shown in Fig. 1, a resistance in the form of a wire R wound on a mica strip M is mounted within the neck and outside the vacuum, and is connected, in series with the grid G. In the arrangement shown in Fig. 3, the wire D is wound on a glass or silica rod M<1> secured by bent-over fingers f to parts P<1>, P<2> of the grid support to which the wire is connected; or a strip of insulating material wound with wire may be riveted to the parts of the supports. In anotherarrangement an insulating tube carrying the wire is mounted between the divided parts of three grid supports. In a further arrangement in which an electrode consists of rings or strips mounted on insulating supports, a separate resistance is connected between each ring and a common terminal. The resistance may be 100 ohms for a 500 watt tube, but may be as. low as 10 ohms or less.