The CV424 is a double beam tetrode transmitting valve based on the commercial QQV06-40 from Mullard.
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 central column has the beam plates and common screen grid. The control grids are separate and mounted close to the central cathode.
Here the shape of the beam plate is clear and within can be seen the screen grid.
The wide glass tube envelope is 44 mm in diameter and, excluding the B7A base pins, is 104 mm tall.
