High hours CTC9

[Electronic M]

I seem to recall when mark tested the CRT two years back at the ETF he said that the CRT was a black matrix type, but my memory has failed me before.

Tom C.

[bgadow]

There were black matrix roundies; as I recall, kx250rider has one, military surplus. I'm thinking 21GVP22? Or maybe a 19V series tube. None of the round crt's listed in the '72 GE Essential Characteristics book are matrix.

[joemama99]

My ctc20 has a 19v tube that is black matrix.Made by rca as a replacement.

[miniman82]

CTC-20 was a roundie chassis, I thought?

[old_coot88]

Originally Posted by miniman82

CTC-20 was a roundie chassis, I thought?

Yes. It's actually a CTC-19 (which drove a 19" rectangular tube) back-engineered to drive a 21" round tube. oc

[old_tv_nut]

You can tell if it's black matrix by looking at it with a strong magnifier and the set turned off. You will see black between the phosphor dots.

Also, it would have "negative guard band," that is, the shadow mask holes are larger than the phosphor dots, so the dots light up completely. In the earlier non-matrix positive-guard-band tubes, the phosphor dots are larger than the holes, and therefore light up only in the center of the dot.