BTH T5-230 VALVE, 1920's

This valve is post 1920 owing to evidence of Gettering (the blackening inside) only used after 1920.
Clearly marked BTH T5-230 a Naval Transmitting type first produced in 1919, with a candelabra cap but instead of two wires at the other end, it is fitted with a later three connection base normally used with RAF valves.
Also the candelabra cap has only one connection, for the filament the other filament wire is brought out to the tip on the other end, with anode and grid on the sides.

Nortel Collection

A1301