Zenith Porthole - Lapeer, MI

[jr_tech]

GREAT FIND!

Originally Posted by jeyurkon

The CRT is a Sylvania 16EP4A. When I first looked at it I thought it was rebuilt because of the joint in the neck. I decided that I shouldn't assume this since it's the first metal CRT I've ever seen up close.

I tested it with a Sencore CR-70. After a two minute warm-up the cutoff was right where it should be and the emission was 3/4 the way up the good scale. It's like the CRT was new!

Good news on the jug... I don't think that a mid neck weld would be typical... I looked at 4 metal tubes in my possession, and only one had a mid-neck weld. Could be a rebuild or a "factory re-neck"... if the stem is damaged or neck glass cracks before pumping, a new piece of neck glass can be added, new gun installed for a second try.

jr

[jeyurkon]

Samswebsite quickly rectified the photofact mixup. It was indeed 91A instead of 91...

Yes, it does use a 6AG7 for the audio. They tied a 0.005uF capacitor across the primary of the audio output transformer. Seems a bit odd to me. I wonder why?

John