The 416C is a planar triode with a mu of 250 designed for microwave amplifier applications to 4 GHz. This tube is an upgraded WE416A/B developed by Western Electric for use in transmitters and low noise preamplifiers. The first example was made by Eimac and was one of 100 made by them before the project was terminated. It is numbered #66 and was a contribution from Lane Upton who moved the 416C factory to Salt Lake City, Utah from Canada. The second base is from a Western Electric. Some WE tubes had the marking on the side and not the base.
Length = 1.75" Diameter = 1.03"
Max voltage = 250
Max current = 45 ma
Fil voltage = 6.1
Fil current = 1.17 amps