I have a bk precision 490b, but the damn thing lies to me...
It always worked fine with all sorts of mono tubes, and 25vxxx tubes and projector tubes, and so on.
But when I hooked up my 21fjp22 that had been it storage forever,, VERY LOW emissions, scared the hell out of me, I thought the tube went dud in storage, took me a while to spot what was going on...
heater V @ 4vac, barely, it could not put out enough power for the heaters in the CRT.
So, I got a 6v 3amp xfomer and it came right up into the "really good" range on all 3 guns...
But, WTF? not enough power to light up a roundie? come on BK...