Hey guys, whats the difference between the 25ap22, 25xp22, 25gp22 crt's?
Is it the glass shield on the screen or some differences in the build material?

the ap is for all purpose the xp is for extra purpose and the gp is for general purpose. seriously i dont know. steve

I would imagine the extra purpose may have to do with the persistence of the phosphor. Maybe they were military-order tubes and had some sort of radar thing displayed 24/7. That would quickly ruin the phosphors

According to GE's "Essential Characteristics", there are minor differences in the three types. Apparently 25GP22 is the oldest of the three, has the older phosphors (not rare-earth), a 1.35A heater, and was not tested for X-ray emissions. 25AP22 seems to be next, with a .9A heater and non rare-earth phosphors. 25GP22 and 25AP22 both have a "A" version with rare-earth phosphors, and the 25AP22A was X-ray tested. Lastly, the 25XP22 has rare-earth phosphors, a .9A heater, and was X-ray tested. There are slight differences in light transmittance (darkness of tint in the glass?); 25AP22 and 25XP22 are given as 41% while 25GP22 is given as 42%.

As Trinescope points out, there are fine details different among them, but all of those are 100% interchangeable. There is one detail that we all should remember: if there's an extra letter in the number (i.e. "19EYP22" or "25AXP22" vs. "19WP22" or "25XP22"), it's a higher grade of tube. That only applies to the older tubes, not the ones that have a V as the 3rd character, which means "viewable area". (the ones without the "V" are total bottle size. So a 25AP22 is really a 23" viewable tube, whereas a 25VDMP22 is a 25" viewable tube with a 27" bottle).

Charles