Found: 15GP22 (I think)

[oldradio99]

Originally Posted by David Roper

Au contraire, somebody will recognize the mounting. The yoke plug is also an item unique to the particular set.

That is why I come here. To the experts.

[N2IXK]

Really looks like a test jig, but I can't see a service shop seeing enough color sets back then to justify such a thing. Perhaps from the development labs of a set maker who was planning to license the RCA designs?

The fact that the tube is a commercial 15GP22, and not the developmental type C-73599 would lead me to believe that this thing was built after the CT-100 was on the market.

[Phil Nelson]

Originally Posted by oldradio99

From the pictures this tube almost looks brand new.

Apart from the getter, the outward appearance of a tube is not very meaningful. I have seen cruddy, scratched-up tubes that perform like brand new, and shiny-looking tubes that were dead ducks. Looking at the getter gives you one clue, but that is not very scientific, either. A better test is whether it gives strong emission on all three of its guns, something you need a CRT tester to check. Even CRT testers don't tell the whole story. I have seen tubes that don't look so hot on a tester, but which make very acceptable pictures when installed in a working TV -- which is the ultimate tester.

Phil Nelson

[WISCOJIM]

Originally Posted by N2IXK

Really looks like a test jig, but I can't see a service shop seeing enough color sets back then to justify such a thing. Perhaps from the development labs of a set maker who was planning to license the RCA designs?

The fact that the tube is a commercial 15GP22, and not the developmental type C-73599 would lead me to believe that this thing was built after the CT-100 was on the market.

Perhaps a Motorola prototype or test jig? It was found in the middle of Motorolaland. (Although it lacks the copper mounts that went into Motorolas production models.)

[oldradio99]

I believe he worked for Motorola and Zenith.

[N2IXK]

That could explain it, then. Could have been part of a laboratory "breadboard" or something like that.

[John Marinello]

Originally Posted by oldradio99

When will you be back?

Probably 12/28. We are celebrating our 1st anniversary together, in Mexico.

[oldradio99]

Originally Posted by John Marinello

Probably 12/28. We are celebrating our 1st anniversary together, in Mexico.

Congratulations. We did our 40th in San Diego this year.

Holler when you get back and settled. If I find another volunteer I will post the results here.

[stromberg6]

Happy about your find. Hope it's a good tube. On the ETF website there are pics of John Folsom's prototype Zenith. It's the only TV among the others with a vertically mounted "signal" chassis, which might explain why your tube is mounted as it is. Could be from Zenith's development labs.
Kevin

[oldradio99]

Originally Posted by stromberg6

Happy about your find. Hope it's a good tube. On the ETF website there are pics of John Folsom's prototype Zenith. It's the only TV among the others with a vertically mounted "signal" chassis, which might explain why your tube is mounted as it is. Could be from Zenith's development labs.
Kevin

That would be cool.

[ohohyodafarted]

Originally Posted by oldradio99

Well I felt ambitious enough to remove the purity coil but that is as far as I think I will go.

From the pictures this tube almost looks brand new.

And it is confirmed to be a 15GP22.

What do you experts think?

I have seen a LOT of 15GP22's in our quest to attempt a rebuild. A good set of getters would be silver to possibly charcoal gray wtih some silver in the margins. I have seen getters that look just like these before. The tubes with getters like these were leakers. IE: they had too much air in them to function.

It is likely that when you apply voltage to the filiments, they will either light dimly and/or burn out.

There is always an outside chance that I am mis-reading what I see in the photos, but I would not be optimistic. I have seen bad tubes with getters that look far better than the ones pictured in these photos. Still, you will need to test it anyhow to tell for sure.

[Pete Deksnis]

Originally Posted by oldradio99

...it is confirmed to be a 15GP22.

Curious to learn what is printed on the connector. RCA perhaps? A date code hopefully. The earliest known RCA 15GP22 has a January 1954 date code.

Pete

[earlyfilm]

Originally Posted by oldradio99

I believe he worked for Motorola and Zenith.

Interesting! Motorola started with RCA CRT's, then switched to CBS Hytron, then when the 19 inchers started failing in warranty, back to RCA CRT's.

James

[dtvmcdonald]

What pressure is necessary for a tube to test gassy?

I was just thinking that if high enough, one could test the
tube without using the heater just by applying a high
voltage to two elements, suitably current limited, or
using a 2 or 6 meter ham transmitter a few tens of watts
coupled in through a tuned circuit stepping it you to high voltage.

Do people try this?

[Dave A]

Does anyone remember a trick using a neon transformer to test a tube for gas? I saw it once years ago and the interior lit up purple...gas.