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The sticker on the valve questions whether this is a Type 020. I can find no details of a De Forest valve that matches this design.
The top of the glass has a ring of letters spelling De Forest but no Type designation can be seen.
The horizontally mounted concentric cylinders with a single strand filament in the centre.
The construction is similar to the European R Type.
This image shows the helical grid fixed to a single support wire. The latter is fixed to the pinch leads at both ends.
The UY base with corroded pins.
The wide glass tube envelope is 34 mm in diameter, and excluding the base pins is 80 mm tall.
Reference: Observation.

 

Pin Connections
UV
1
2
3
4
f
a
g1
f

 

Updated December23, 2016.
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