Stupid CRT question

[freakaftr8]

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?

[rcaman]

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

[zenith2134]

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

[trinescope]

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%.

[kx250rider]

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