Frankly, your best bet is to find another AN/ALR-56
display. One should
turn up eventually. What is the IP- number of the box?
Here's the IP number:
IP-1164B/ALR-56C
The NSN is 5865-01-289-9651EW and it's made by Loral Electronic Systems.
I did verify that the tube is indeed a 4" tube. The 4AP10 CRT number that
you mentioned I found online for $85.
If you have access to the documentation on the unit I've got, I would
_love_ to get the tube specs and pinouts.
It also has a set of symbols like this: [O] burned into the 12 o'clock
position. Any idea what that's for?
Thanks!
g.