The experimental valve VX510 is a mystery and the glass is broken so that the full details are missing. The copper section is very heavy and has the evacuation pip at one end. The connections on the right are co-axial suggesting that this operated in a co-axial cavity. It could be a high power triode or a klystron.
The Type designation and the serial number E153.
The SERL name and logo. SERL stands for Services Electronics Research Laboratory.
The broken glass end. There is a copper cylinder with insulation within and a copper wire.
The wide metal tube envelope is 80 mm in diameter and, including the base connections, is 355 mm tall.
Updated October 24, 2021.