The CV245 is a pentode based on the 4328D. It was used by the GPO and there was known as the POVT185.
The KB/F identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the F identifies the maker as STC, Paignton.
The printed designation information.
Looking up from the pinch reveals the wire grids and the round cathode tube. The heater is a single hairpin.
The classic envelope is 37 mm in diameter and, excluding the IO base pins, is 100 mm tall.
