5Z4G CV1863 AIR MINISTRY WW2 BRIMAR 52KU CV2748 R52

The CV1863 is the Air Ministry /Army variant of the 5Z4G.  Designed for professional equipment, such as radar and communications equipment with circuits in which valve cathodes carried large signals and had to 'float' at voltages well below that of the chassis.   

Capable of a 40 Watts total power, this rectifier was made by several manufacturers and as you can see from the title listing came under the guise of many different reference numbers.   

This variant shows full emission and is a Brimar Air Ministry variant as evinced by the glass-base interface sleeve.  A very nice device indeed.