The CV304 is an output pentode and equal to the prototype, the EL22 from Mullard.
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 control grid is wound on copper supports and has heat radiating fins on the support tops. The insulated heater looks to be passing six times through the cathode.
The base components. The cathode tube is a flattened oval but not completely flat across the width.
The Wide glass tube envelope is 27 mm in diameter, and excluding the B8B base pins is 62 mm tall.
