Sensibly equivalent¶ to:
The CV2239 is an amplifier triode designed for dry battery operation. The Hivac range of miniature wire-ended valves were used in hearing aids in the 1950s and early 1960s.
The B5G/F base has a red dot to indicate pin 1.
The CV number indicates that these valves were also used in equipment used by the UK government. Portable personal radio communications would be the obvious application.
The XFR3 is the commercial equivalent of the CV2239 and the prototype was the 5676.
The thin glass envelope is 8 x 5 mm in section, and excluding the lead-out wires is 42 mm tall.
References: Datasheet & 1040.
Absolute Maximum Operating Conditions¶
Updated October 12, 2013.