|
Probably less of a defect than an artifact of the manufacturing process which was different than that of the 21AXP22 and later tubes. I'd have to go back and re-read the RCA process description to see how the dot pattern was laid down, but I do remember that it was silk screened instead of a photoresist process used on the later tubes. Perhaps a layer of binder material was applied first, or it comes from the silk screening of the phosphors.
__________________
Erich Loepke
|