J M Noeding wrote:
Any idea what this tube is used for, see
http://home.online.no/~la8ak/e81.htm

73,
Jan-Martin
---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm

It's a 'head on' photomultiplier tube.
They were used in flying spot scanners,
and noise generators in radar jammers.