The CV346 is the UK government specification valve with the 7Z4 and EZ22 as the commercial equivalents. The CV346 is a full wave rectifier on a Loctal base.
The anodes are pressed into a cross shape to offer maximum radiant area. The anodes are identical in shape with an offset cylindrical space for the single cathode. This offset shape allows for two main supports and the common cathode.
The cathode is oxide coated and not connected to the insulated heater.
The wide glass tube envelope is 27 mm in diameter, and excluding the B8B base pins is 67 mm tall.
References: Datasheet & 3002. Type CV346 was first introduced in 1948.