The M8223 shows the final design format of the valve voltage stabiliser, it would strike at 165 Volts and the regulation would be 5 Volts for changes in current of 5 - 30 mA around the design voltage of 150 Volts.
This exhibit is a special quality valve.
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 reverse carries the CV4020 Type designation and the alternative commercial Type designation of 0A2WA.
The construction has a rod anode within an outer cylinder. For vibration resistance the top mica is doubled.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 58 mm tall.
