The CV1629 is a directly heated mercury vapour rectifier. The maximum PIV is 11 kV and the average anode current is 1.25 Amps. The prototypes were the RG3-1250 and the GU21. The old GPO code is POVT197.
The GES paper label. On the bottom left of the image can be seen the droplets of mercury.
The main components are shielded due to the UV produced by the discharge.
The anode is a cylinder closed at the top end.
The wide glass tube envelope is 57 mm in diameter and, including the GES base, is 245 mm tall.