Spot melting failures in transmitting valves and their prevention

In the recent past short-wave high-power valves have frequently failed through local melting of the glass. Investigation has shown the cause to be dielectric losses. The electric field distribution and the glass temperature were studied and as a result an improved electrode structure was introduced. This has proved satisfactory in one type of valve and it is proposed to extend the modification to water-cooled valves. At the same time an improved procedure for handling the valves has been found.