The CV2031 is a special version of the CV2000 for use in GPO line amplifiers.
The valve is an HF pentode fitted with flying leads in place of the B7G base pins.
Further back in the development chain is the CV4002 also with flying leads. The B7G version of the CV4002 is the CV4014 the special quality version of the CV138 and that is the EF91.
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.
This looks like two anode plates joined by a strap with a screen between. There is significant screening at the top where even the tops of the grid supports are shielded and there is also bottom screening. The mica discs are doubled to confer vibration resistance.
At this angle the control grid can be seen to be wound on copper supports.
The Paxolin base disc guides the lead-out wires and there is an additional centre tube that also has a connection tape welded to it.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G/F base pins is 47 mm tall.
Reference: Data-sheet. Type CV2031 was first introduced in 1964. See also1964 adverts.
