Summary

Inert gas cold cathode rectifier developed by Charles Grover Smith for the American Radio and Research Corporation (Amrad) in the early 1920s. It went into production in 1922 but it was only suitable for high voltage applications such as transmitters.
Manufacturer: American Radio and Research Corporation, Medford Hillside, Massachusetts, USA.
Tube uses a cylindrical iron anode and a carbon cup cathode.

Physical Description

Conical globe bulb with Edison screw base and exhaust tip on top.

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