Successful Rebuilt of a 15GP22 at ETF - Page 2 - Videokarma.org TV - Video

Dave A · #16 05-03-2010, 11:40 PM

Jerome,

I will be there Friday and looking for you to welcome you to our Delaware Valley Historic Radio Club monster meet at Kutztown. The place to be especially for you to take the congratulations on the 15GP22 effort.

To those who missed the ETF convention and have seen the photos, it was every bit as wonderful as you can imagine.

Pete and the two Steves did an amazing job cobbling this tube in a ETF donor cabinet with Pete's modified chassis. The first glow was a red flat-field from a generator albiet a bit blotchy. Then the fun began. Purity adjustments were odd. G1 adjustments were not responding properly. The distinct smell of ozone was in the air. That was a plate cap wiring fault and a spare was found but still continued to arc for the duration but did not affect the pix.

The chassis socket connection had to be turned past it's 55 year historic natural position. That gave the clue that the guns may have been mounted out of phase. Moving the RGB G1 connections proved that. The original circuit design was specific for the colors and moving them around to get a picture did not involve moving all the circuits. Close counted in this case and it was good enough for the first try. Convergence was left for a later day. The colors were there and there was no giant sucking sound of air rushing in. And the set ran like Secretariat for the duration.

The actual restored tube was something to see. The neck showed the usual glass welds and the original base was used even with it's missing chunks of base material and liberal amounts of adhesive showing. There were some splotches of contamination on the phosphor plate and given the train-wreck of a tube to use, it was not a deal-breaker. If you looked close at Judy Garland it could be seen but can be considered minor considering the success. And yes, clean the glass when you get yours rebuilt.

The infamous glass frit solution was interesting to see. It looked like someone smeared epoxy over the seams and was only used in this case on the bell side of the tube seam. But it was hard as a rock. Jerome can inform further as to how this will be done for future tubes.

There is still no known price for now. A work in progress that I was so happy to see happen right in front of me. Kudos to Jerome for his and RACS work on this and flying through volcanic ash to show us.

Find him at Kutztown and congratulate his effort,

Dave A

jhalphen · #17 05-06-2010, 09:52 AM

Hi Dave,

What can i say! (blush)

Will be glad to see you & other ETF collectors at Kutztown.

Latest news with RACS is that i will send my two 15G's for rebuild simultaneously. They are not too sure about the feasability of the CRT with the entire front bowl detached so i will also send my operational tube which has a Red Gun 99% dead.

Best Regards

jhalphen

wkand · #18 05-10-2010, 07:01 PM

Where did the gun assemblies come from for this rebuild?

sweitzel · #19 08-06-2010, 01:15 PM

Bumping this up to the top. It's been about 3 months since this rebuilt tube was demonstrated, I was curious to know if the tube has remained sealed? I seem to recall John and Bob's rebuild attempt at Hawkeye sadly went to air again within a month or 2 of their rebuild.

RobtWB · #20 08-06-2010, 01:34 PM

I believe most want to know if this rebuild is still under vacuum.
Has the rebuild been installed into a working set? Is it used? That is, is it powered up and watched regularly? Has the tube been allowed to reach operating temperature and then powered off/turned back on? Has the tube spent its rebuilt life in a shipping container stored in an essentially constant temperature environment?

David Roper · #21 08-06-2010, 01:46 PM

The RACS rebuilt 15G lives in a restored CT-100. The Early Television Foundation posted an update saying that it was still working fine on June 6th.

No news is good news...?

Steve McVoy · #22 08-06-2010, 02:13 PM

Still working today. I'll update the site.

The tube is in a working CT-100. It survived an air shipment from France, and since then the room it is in has ranged from about 70 to 85 degrees. We turn on the air conditioning on the weekends, then off during the week.

Jerome Halphen has two more tubes that he plans to take to RACS soon.

miniman82 · #23 08-06-2010, 02:46 PM

I assume the issues sourcing electron guns remains?

Steve McVoy · #24 08-06-2010, 05:26 PM

At the present time, and for the near future at least, there is a place to have the existing guns rebuilt.

WA3WLJ · #25 08-07-2010, 05:06 AM

Humditity ?

Steve McVoy · #26 08-07-2010, 06:00 PM

Humidity also changes. When the air conditioner is on (weekends), humidity is relatively low. During the week, it gets up there - Ohio summers are typically very humid.

JB5pro · #27 08-08-2010, 12:47 PM

Quote:

Originally Posted by kx250rider

That's VERY encouraging!!!! I hope however, that if indeed successful in the long term, we can get someone in the USA to do it. I'd hate to think of the nervous breakdown I'd suffer, mailing a 15GP22 to & from Europe. And I have the feeling that the FAA would have a problem with us buying an extra seat, and flying the tube by hand. I did that with a prewar Andrea TV (domestic flight in USA), but that was pre-9/11.

Charles

The impression I get from this site is we have not only some of the most intelligent and knowledgeable people in the world but also some of the most successful in general and therefore it is likely somebody could get a private jet to transpost a 15G. Just a guess but I seem to more often be right that wrong... too many words again? Maybe still too crazy/pscho sounding?

NewVista · #28 08-18-2010, 01:28 AM

In case I missed it, how do you tell if a tube like 15GP22 / 21AXP22 has air ? As you would want to know and be cautious testing. Do they all have neck getter to look for for instance ?

JB5pro · #29 08-18-2010, 03:59 AM

Quote:

Originally Posted by NewVista

In case I missed it, how do you tell if a tube like 15GP22 / 21AXP22 has air ? As you would want to know and be cautious testing. Do they all have neck getter to look for for instance ?

There is much detailed info about this in at least one thread but if the getter is dark rather than silver it prolly has enought air to burn out filaments. If the silver is good but has that classic "gassy" look to the picture than it is gettin aired up and likely soon to burn out filaments. My info may be off a bit in one way or another.

NewVista · #30 08-19-2010, 09:04 AM

The inside black conductive coating on 21AXP's have what looks like a "window" strip at top of guns .25" x 1.5" (dark silver non transparent) - is this the getter ?

Where is getter on 15G's and what size is it ?

I look on later 21" color roundies and they only have conductive coating + 1" red band - and no getter ? (because they were more confident of seal ?)