Rebuilt 15GP22's?

[Tom_Ryan]

True, the 15GP22 uses electrostatic convergence; however, regardless of the method of convergence in any color tube, the outcome is the same - focusing the electron gun on the phosphor plate. Of course, the physical principles and subsequence circuitry is different (15G uses electrostatic fields and the 21AX gun uses magnetic). Say, glad use did mention the use of 21AXP22 guns - it would be cool to find out who tried it and what finally came of it.

On the subject of phosphors, I've had the unpleasant experience of discovering the non-aluminized black & white tube phosphor the easiest to damage if you suddenly break the seal off nipple at the base of the gun. You can blow away a circular patch of phosphor several inches in diameter off the face plate. I recall calculating the velocity of air once as it enters the tube. At the instance the nipple is broken air rushes into the tube at something like up to 300 miles per hour - depending the length of the tube. Air traveling at this speed does a nice job of blowing away the phosphor. Sort of like sand blasting the phosphor off the glass! Of course, aluminized phosphor is strong enough that this doesn't seem to happen. Guess if you're going to go to all that trouble to rebuild a 12AP4 pre-war tube to recoat the phosphor you're basically building a whole new tube. At least it looks authentic on the outside - not sure how safe the integrity of the old glass bottle would be though. Why not take the last step and replace the old glass too!