The V246A/2K 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 V246A/2K looks to be a selected V246A/1K but no specific data has yet been found.
The resonator connects to the copper disc and also to the base pin 6. The central bar is the output probe.
The other side carries the UK Government procurement code CV485.
The thin glass tube envelope is 19 mm in diameter, and excluding the B7G base pins is 73 mm tall.
