I used to dream of finding some WE 300B tubes stashed somewhere. Never found any 300B's or anything super rare/expensive,...
One of my first duty stations was NAS Lakehurst, NJ.
Here is a schematic of where they used the 6A6, C6A's...in the control panel of a Stable Element..this was the top secret device that allowed our battleship to maneuver and shoot accurately....this device measured the roll and pitch and outputted it via synchro selysn devices to the MK8 Rangekeeper to produce Gun Orders for the 16" and 5 " battery. The secondary battery called these things Stable Elements and the 16" side called them Stable Verticals.
The gyroscope had a electromagnet the stayed in the vertical as a set of figure eight coils suspended in a "umbrella" over it that moved on gimbals with the ships motion and produced a small current the had to be sent to the control panel via cables for amplification etc....a wonder device for the times!
Talking of Veterans Day, it is something that has sadly fallen off the radar here in South Africa - limited to a few small functions. I always think on that day of my grandfather, who fought in WW2 in North Africa and Italy. My Mom was a little girl then, and didn't see him for 4 years.