Picture tubes--rate them...

[Electronic M]

The 15G was on par with the 21AXP and metal cone monochrome CRTs of the 50's as far as reliability goes. Why the 21AXP is harder to find than the monochrome tubes and the 15G harder to find than the 21AXP ultimately comes down to how many of each were made.

Also I have seen one (and heard of some other) 21FJP tube going to air without being necked so those tubes are not completely leak proof either.

You over look the fact that the Japanese beat our 23EGP to market with their own tube (the number escapes me at the moment).

Performance wise it is dependent on phosphor color rendition (the round tubes especially the earliest ones have it hands down in my opinion) and the electronics driving the tube. Most roundy tubes I've seen run tend to have soft focus, but on a CTC-4 (with a 21FJP retrofitted in) and a Zenith roundy I got last year the focus and video circuits drive the tube to have a monochrome picture with detail sharp enough to rival my Zenith Chromacolor.