The CV2004 is a CV140 (commercially the 6AL5) double signal diode fitted with tapes to the pins.
The two valves are completely separate flat structures separated by a plate screen. This clearly shows the signal usage, where it is important to keep RF isolation.
Mullard designed these diodes for vision and sound detection.
The KB/DA identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the DA identifies the maker as Mullard Radio Valve Co., Blackburn.
The two diodes with central electrostatic screen.
The standard construction of a small signal diode.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 48 mm tall.
References: Data-sheet & 1040. Type CV2004 was first introduced in 1953. See also1953 adverts.
