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Originally Posted by jpdylon
If RCA originally designed these tubes, you would think there would be archives somewhere of the tube designs and how to manufacture them.
I would think it would be cheaper to manufacture brand new tubes than to break so many in existance trying to find a way to put a new phosphers and gun assembly in an old shell...
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Good point. Actually there is an archive of information right under everyone's noses that was published in the proceedings of the IRE Vol. 42. Here it is:
Grimes, M.J, Grimm, A.C., Wilhelm, J.F. (1954).
Improvement in the RCA Three-Beam Shadow-Mask Color Kinescope. Proceedings of the Institute of Radio Engineers. New York, N.Y., pp 315-326.
In this article Grimes, Grimm, and Wihelm describe the advances RCA has made in the design of the all glass color kinescope type 15GP22. Over what you ask? The original prototype was not the all glass tube everyone knows and fears can't be rebuilt today. The 15GP22 design originally started life as a modified 16AP4 metal shell. The 16AP4 was a glass-metal tube that found use in b&w sets that first appeared in the late 1940's. RCA simply added a color viewing screen assembly consisting of a shadow mask + phosphor dot plate and then added a tricolor electron gun. However, RCA quickly discovered a bunch of problems inherent to glass metal tubes adopted for color use. The authors interviewed many RCA engineers and assembly line workers to write their research paper.
Maybe even the 80+ year old tech that Charles knows was interviewed. 
The authors disclose a ton of information that led to changes in materials, assembly techniques and tips for factory production. For example, tube evacuation techniques, e.g. placing the mu metal shield outside the tube to reduce outgassing, improving the tension on the shadow mask by increasing heat dissipation 2.5 times to allow for increase beam intensities to produce brighter pictures, and changes to the blue phosphor to help reduce the classic "trailing edge" effect. The authors even reveal the composition of the shadow mask and the dichromating process used to improve thermal radiation and reduce buckling. Lots of other stuff is discussed too.
But the real kicker for RCA in moving to an all glass tube design was that it couldn't build the glass metal color tubes fast enough. The authors reveal that RCA management wanted a new color tube to role off the assemble line every 2.5 minutes. The 15PG22 did improve upon the modified 16AP4 in three ways: improved tube performance, parts interchangeability, and decrease in tube cost. RCA eventually lost millions on this tube because the demands of mass production were never realized. The tube also had a high mortality rate in the field. Tubes were failing after assembly or losing their vacuum after delivery in new sets or just simply sitting in inventory. So, anyone who has a working 15GP22 tube needs to understand that it is essential to VacSeal seal all vacuum joints on this tube immediately to guard against the possibility of vacuum failure in the future.
Corning Glass Works originally manufactured the molds that made the face plate section and the cone (funnel) section of the 15GP22. Prior to assembly a metal flange is sealed onto each part separately. This was done by RCA in a refractory oven using similar techniques for b&w tubes. Glass frit is used to bond the metal flange surface to the glass at extremely high temperatures.
NOTE: at this point you are only sealing metal to separate glass parts. They are not yet joined together to form a CRT. The second major assembly step was the use of a very complex jig called an assembly lighthouse. The lighthouse was used to set the mechanical position of the phosphor dot plate to the shadow mask. A special jig is also needed to secure the shadow mask to the cone section flange collet assembly at the correct tension. The phosphor dot plate was then attached to a collet assembly on the face plate section. Once the alignment was completed in the lighthouse jig the flanges of the two halves were then heli-arc welded together.
From my experience, a tri-color electron gun assembly may be substituted into a 15GP22 as long as it meets one very critical requirement: the electron beams from the gun must focus at the plane of the phosphor dot plate exactly as simulated using the small light source in the alignment lighthouse during manufacture of the original tube. This would first require precise mechanical alignment during a rebuild so that the replacement gun is attached at the correct position, and establishing the correct electron field density to focus the electron beam during operation. 
Finally, I would like to share with everyone what the authors had to say about baking the assembled 15GP22 after final assembly. This was especially critical during outgassing and evacuation. The authors pointed out that the manufacturing of b&w tubes used higher temperatures which were found not suitable for manufacturing color tubes. Why? Slow thermal cycling is required to prevent the shadow mask from bucking. The face plate must be also shielded to prevent it from cracking due to non-uniform thermal shock. Most importantly baking temperatures were tipped off at 300 degC.
See, when you stop and think about it the 15GP22 resulted because RCA engineers failed in making the "old design" 16AP4 glass-metal color tube work cost effectively. Grimes, Grimm, and Wihelm provide a wealth of information in their article about 15GP22 construction and assembly. The article also reveals what later become known as common sense techniques for color tube production: success depends on using moderate temperatures, slow thermal cycling and long tube evaluation time.
Tom Ryan