The HVR2A is a half wave low current EHT rectifier from Mullard. It would have been designed for provision of EHT in such applications as Radar and Oscilloscopes where Cathode Ray Tube displays were used.
The HVR2 is indirectly heated with a four Volt heater and the HVR2A is quoted as being directly heated with a two Volt filament like the HVR1. But our exhibit is clearly an indirectly heated valve. On test the heater consumes 1.65 A at 2.0 V.
The glass pillars holding the anode clearly signify a high voltage devic.
The insulated heater within the oxide coated cathode tube.
The large cylindrical anode allows a distance to be maintained to the cathode thus avoiding flash over.
The insulated heater is a single strand folded to pass through the cathode four times.
The cathode tube has reduced diameter at the top where it is securely held in an insulating sheet.
The classic envelope is 45 mm in diameter, and excluding the B4 base pins, is 112 mm tall.
References: Data-sheet & 1043. Type HVR2A was first introduced in 1937.