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[Rob]

John,

In my experience screen burns from deflection failure are small, sharply defined burns. Phosphor burn from ion bombardment are larger sized darkened smudges. I have a Dumont 15AP4 that has no aluminizing and a straight gun (no ion trap). It is like new for emission and has no ion burn. When I tested it for emission when I got the set home it had obviously not been run for decades. It immediately shot up to perfect emission without delay, clearly a low mileage CRT. Many of these old CRT's read good, but only after taking a while for the emissive coating on the cathode to reawaken. It is in a very rare Sightmaster 15-S-1 set.

This tube is kinda crude, has some shape distortions, probably from almost colapsing in the baking process. If I own a vintage CRT that I'm afraid might blow up in my face from merely handling, this would be the one.

Rob