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 commercial Type designation 6058 is also present on the glass.
The KB/D identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the D identifies the maker as Mullard Radio Valve Co., Mitcham.
The usual signal diode construction with a small active centre and side flanges to dissipate the heat.
The twin diodes are separated by a central electrostatic screen. As a professional device the top and bottom mica discs are duplicated. This confers vibration resistance and makes the valve durable for applications such as mobile and aircraft systems.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 46 mm tall.
