Successful Rebuilt of a 15GP22 at ETF

[old_tv_nut]

Originally Posted by NewVista

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 ?)

All tubes must have a getter. It is essential to getting the final vacuum quality, even if the tube does not leak. Sometimes it is somewhere not visible, like under the conductive aquadag coating.

[JB5pro]

I think it is an incedible and beautiful thing that all of you great men are doing to restore these 15G's. I just had to write that.
It will be amazing to me to someday see a picture on one in person.

[jhalphen]

Good day Gentlemen,

I have been procrastinating over the summer (RACS closed) to decide weither to send my working 15GP22 for rebuild straight away, or attempt a last resort test to revive the nearly dead Red gun.

I have also received 2 sturdy CRT boxes to ship the 15Gs.

As of now, Blue & Green guns are A-OK, the Red gun needs a "preheat" for 30-40min at 7V to display red. If the set rests for a week, the process must be done again.

RACS suggested i do the following test to decide if the Red gun is revivable before deciding to ship it to them:

TV off, socket removed, power to filament only:
- 7Volts, 1min
- 9V, 1 min
- 10V, 1 min
- 12V, 2min

Reduce to 9V, "cook" for 45min.

Then, Connect K(Red) to G1(Red)
- Connect a 40W/220VAC light bulb between K+G1(Red) and G2 (Red)
- Apply a 300VDC source between K+G1(Red) and G2 (Red)
- Duration 30 to 45 min.

Question 1: i have a solid-state DC/DC converter, 9V to 300V, 30mA, do you think this intensity is enough?

Option 2: Eckhard is kindly offering help under the form of a Müter BMR90 or Müter BMR 107 CRT rejuvenator.

Quote from Eckhard:
"I have brought an absolutely weak red gun (zero beam current) back to life with 0.9 mA after rejuvenating and with a lifetime guarantee of 2,000 hours (according to the manual). The rejuvenator has a computer-function which measured the actual emission of the gun and computes the exact rejuvenating power for the best results". - sounds encouraging!

If i go for this option, i will need to build a socket adapter for the 15G. From the GE pdf on the 15G it uses a JETEC-20A type base (see refresher data below).

Would somebody have a NOS, second hand, retrievable connector from a dead PMT tube or a source that still sells these? i looked at Digikey's bewildering choice of connectors, got lost & found nothing. If you have something, please PM me with price + Airmail to France.

Hammamatsu Photonics sells new ones for use with nuclear research PMTs. Before contacting them ( high $ price and probably won't sell alone without a PMT tube order) i am trying my luck here with the ressourceful VK gang.

Once this is sorted out, 1 or 2 of my 15Gs will be sent to RACS for rebuild.

Thanks! for reading this long message,

Best Regards

jhalphen
Paris/France