The CV402 is a protective spark gap. The commercial Type designation appears on the base as GXA80.
The KB/QG identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the QG identifies the maker as English Electric Valve Co., location unknown.
The English Electric logo without any reference to AEI places the production as before the 1968 merger.
The EE logo.
The central ceramic tube with discs top and bottom. The spark gap is thus hidden.
The wide glass tube envelope is 30 mm in diameter and, excluding the IO base pins, is 63 mm tall.
