This exhibit is an STC V246A/1K also labeled as the CV228. The attached datasheet is the CV specification and our other V246A/1K has the STC data-sheet.
The valve is a Heil Tube. Named after its German inventor, the Heil tube is a velocity modulated oscillator and the Heil tube was developed by STC during WWII. Unlike the klystron the electron beam in the Heil tube is focused by an external magnet. This refinement was originally added to keep the bunched electrons together as the electric charge would, of course, tend to repel the electrons one from another.
The standard CV designation was CV288 and a selected number were alternatively designated CV485. The copper disc is internally connected to the resonator at pin 6.
Two CV228's were used in the transmitter of the Wireless Set No. 10 Mk.II used to provide eight channel communications (telephone) during the D Day landings. The Mk.I used the split anode magnetrons Type CV79 and CV89.
The glass to metal seal shows up as the red of the copper oxide wetted by the glass.
The STC logo and Type designation.
Resonator side view.
The thin glass tube envelope is 19 mm in diameter, and excluding the B7G base pins is 74 mm tall.
Reference: Datasheet. Type CV228 was first introduced in 1957.