This is a mystery as the VR71 does not seem to exist. The shape suggests a Cossor valve but the identification lettering is virtually obliterated.Looking from the base the centre electrode is an oxide coated inverted V filament. The anode connects to the top cap and there look to be two grids but the grid windings cannot be seen.
The lettering is badly damaged there looks to be a V and an R but it could be a P. Too much guesswork to be certain.
The anode connection, top mica and screen. The two grids are strapped together so this acts as a triode. The classic envelope is 44 mm in diameter and, excluding the B7 base pins, is 108 mm tall.Reference: Observation. |
Updated February 24, 2022.
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