STC V240C/2K, 1940's

Known as a Velocity Modulated Valve or 'Heil' tube for use as a Microwave a oscillator and requires a magnetic field for operation with the Anode connected by a Housekeeper seal (the copper disc), invented by A.A.A. Housekeeper, who solved the problem of making ductile metals bond to glass.

In1935 A. Arsenjewa-Heil and O. Heil (wife and husband) were acknowledged for their contribution to velocity modulation theory .

A0643