What's the need for an ion trap on an aluminized picture tube

[cbenham]

Originally Posted by benman94

The 12LP4A just has a grey filter faceplate; it's not aluminized. The 12LP4C is, as is the 12KP4 as you mentioned. The 12KP4 shouldn't require an ion trap. Now rebuilders have made things a bit murky. Some rebuilders aluminized tubes, and I would venture to guess that some probably rebuilt 12KP4s with angled guns if that is what they had on hand at the moment. At the end of the day it doesn't really matter what the number on the tube is. If it uses an angled gun, use a trap. If not, leave it off.

Here's where the CRT identifying system breaks down:
The 12KP4 is an aluminized CRT with a clear faceplate. The 12KP4A is aluminized too, but here the 'A' indicates a
65% transmission gray faceplate.

For most other CRTS of this period, the 'A' indicates an alumin9ized CRT.
Go figure.