EF50

In the field of electronics, the EF50 is an early all-glass wideband remote cutoff pentode designed in 1938 by Philips. It was a landmark in the development of vacuum tube technology, departing from construction ideas of the time, that was essentially unchanged from light bulb designs. Initially used in television receivers, it quickly gained a vital role in British radar, and great efforts were made to secure a continuing supply of the device as Holland fell in World War II.

The EF50 tube is a 9-pin Loctal-socket device with short internal wires to nine short chromium-iron pins, making it suitable for Very High Frequency (VHF) use.