Summary

The 239A was a war robust version of the 215A. It is housed in a larger bulb and filled with a standard American 4 pin base. It has a 1 volt directly heated cathode.
The 239A was introduced in 1927 but does not appear in a Western Electric catalogue dated 1933. It appears to have had a fairly short commercial life.
Manufactured by: Western Electric, USA

Physical Description

Tubular glass bulb with exhaust tip on top broken off. 4 pin American style base (UX),

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