|
The advent of the aluminized screen was the last step toward eliminating the ion trap and bent gun construction and you're right that the small-neck tubes were the first to eliminate the ion trap. There were, however, some large-neck test CRT's that didn't use ion traps, but I have yet to see one of those without a burn in the center of the screen. The burn could be from ions, but it could have also resulted from operation of the tube without deflection. I always take my test CRT out of its case and install it through the yoke of the chassis that I'm testing, but some previous owner of the tube might not have done that. It only takes one time to burn the phosphor.
|