WT50 diode, an external grid triode. The "grid" or control electrode is missing from this sample. If it were present it would consist of a few turns of wire hound in the waist of the bulb.
Manufacturer: Welsh Electric Lamp Corp. 72 Boylan St., later 38-40 Clinton St. Newark NJ, USA.
Manufactured for: Radio Research Guild, 9-15 Clinton St. Newark NJ, USA.

Physical Description

Cylindrical bulb with top exhaust tip and slight waist near the top, fitted to a 2 pin bayonet base (brass shell), with a 3rd wire coming between brass shell and bulb, mounted on display block.

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