The CV6137 (commercially the 4CX250B) is the classic RF Power tetrode valve for VHF and low UHF applications. The base is a special version of the B8F because it has to incorporate the forced air system, a matching ceramic chimney was made for the base, and the control grid was connected to the central metal spigot.
The KB/Z identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the Z identifies the maker as MO Valve Company, Hammersmith.
The top of the anode tube is marked GEC and 4CX250B as well as Made in England. The gold plated heat sink fins are held within the outer ring to ensure that the forced air cooling passes over them.
The B8F base pins mounted in ceramic and gold plated.
The ceramic disc seal envelope is 35 mm in diameter and, excluding the B8F base pins, is 49 mm tall.
Reference: Data-sheet. Type CV6137 was first introduced in 1960. See also1960 adverts.
