The CV4025 is the UK Government procurement specification and the commercial equivalent is the 6058 and the prototype was the CV140. This special quality double diode is based on the 6AL5. These diodes are for signal rectification at medium frequencies eg. video.
The KB/K identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the K identifies the maker as ETEL, Electronic Tubes, High Wycombe.
The two diode sections are separated by a central electrostatic screen.
The active area is small with the majority of the width used for heat removal and fixing.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 46 mm tall.
