Does a B&K 747 test different tubes than a 747B?
 

Thanks for info. I think I read this discussed here before but can't figure out how to find it yet. I think I read that those two tube testers check different tubes.

Apparently not
 

I checked other sites and found a report that it has a couple function upgrades that are somewhat insignificant.

Do tubes for things like TV cameras, station equipment, old computers have unusual tube #'s?
I am amazed at how many variations of every single thing there are. I am surprised there are enough people to do all the behind the scenes work.