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This is clearly a disc seal triode with a forced air cooled anode but apart from the number 2381 inside the envelope no identification can be seen other than the hand writted HF on the cathode disc. The heater/filament is open circuit.
The cathode and filament end. The evacuation tube will be under the domed metal end. A shape that allows for it to be pushed into a base.
The re-entrant glass tube at the anode end would allow the air to be forced over the glass to metal seal and keeping it at a safe temperature.
The anode is copper on the inside of the envelope.
The complex pattern of slots and grooves to maximize the surface area cooled by the air blast.
The copper grid disc has a separate frame grid screwed to it.
The frame grid is single sided. The copper machine screws fixing it to the grid disc can be seen to have been tightened to the point where the copper has been deformed.
The wide glass tube envelope is 46 mm in diameter, and including the base is 123 mm tall.
Reference: Observation.


Updated April 10, 2019.
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