Sensibly equivalent¶ to:
The VR in the VR38, tells us that this was an RAF designation prior to WWII. The valve, on a B5 base, is an ampplifier triode for detector of audio amplifier applications.
The etched identification lozenge is clearly of M-OV style and the MHL4 looks the same.
The opacity of the envelope veils the internal structure.
The classic envelope is 42 mm in diameter and, excluding the B5 base pins, is 91 mm tall.
References: Datasheet & 1040.
Absolute Maximum Operating Conditions¶
Updated April 03, 2015. shape:classic construction:pinch type:triode age:1920.1930 base:b5 heater:4.0v pins:5 pin:1.a pin:2.g1 pin:3.h pin:4.h pin:5.k