Summary

'Special Quality' V.H.F. Twin triode. Similar to the commercial types ECC91 and 6J6.
Special Quality valves were made "for use in equipment where mechanical vibration and shocks are unavoidable and statistically controlled major electrical characteristics are required." (From the data sheet for this valve.)
The inscription 6101 is an alternative type number for this valve; CV4031 is its military designation.
6Z1 is the Philips/Mullard factory code for this type, R5E3 is the factory code that indicates that it was made by Mullard Radio Valve Co., Mitcham (UK) in the third week of May 1965.
WH is part of the CV code which means August 1965 and KB/D again indicates that it was made in the Mullard Mitcham works.
The difference between the factory date code and the CV date code possibly indicates the time between manufacture and labelling.
6.3 volt indirectly heated cathode.
Manufacturer: Mullard Radio Valve Co., Mitcham works (England).

Physical Description

Miniature tubular bulb with seven pin glass base, with exhaust tip on top.

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