The CV4010 is the UK Government code for the commercial M8100 which in turn is Mullard's special quality version of the EF95. It is an RF pentode for VHF and above. The CV specification gives the prototype as the VX8100 and that other Type designations for the valve are 5654, 6AK5W and 6096.
A flying lead version was made and named the CV4050.
The KB/QDD identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the QDD identifies the maker as English Electric Valve Co., Stafford.
The actual origin of the /QDD is not clear. Speculation is that it was made by English Electric for Mullard.
The folded and stitch anode and the three wire grids within. Welded to the cathode lead is a screen that ends with a disc sitting on the glass base between all the pins.
The sides of the anode are flat. The apparent indentation is a shadow.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 36 mm tall.
References: Data-sheet & 1040. Type CV4010 was first introduced in 1948. See also1948 adverts.
