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Old 10-06-2017, 10:56 PM
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Westinghouse H840CK15

I picked up the Westinghouse today from Dwight here in the Metro-Detroit area. My father went with me, and after going out for a late dinner, we decided we weren't going to try to carry the chassis plus 15GP22 up to my walk-up apartment.

Since I have sold off most of the items that my parents were very graciously allowing me to keep in their unused basement, we decided to take it out to their house near Flint to stay temporarily. He called my mother, explained the situation, and she begrudgingly allowed the Westy in the house. Thanks Ma!

We set both chassis on a table in the main room and moved the cabinet back deeper into storage.

We turned immediately to testing the 15GP22, and were pleased with some slightly encouraging signs. The heaters lit normally using my regulated 6.3 volt supply, and drew normal current. It passed a date with my tesla-coil, and I put it on the Beltron using hastily made clip leads. To our surprise, the tube shows excellent emissions on all three guns, with the red looking the strongest, and the blue looking slightly weaker than the green (and taking a tad longer to "wake up").

Neither he nor I saw any pink or purple glow between any elements in the gun like I have when testing other gassy 15GP22s.

The meter was not pegged on any gun, but we still haven't tested cutoff (the Beltron can not do this). Like the idiot I am, I left my Sencore at the museum by mistake, so I will have to wait for further testing in November when I get back from Ohio. I think the Sencore will be a bit more conclusive. If I find I can get the meter to peg on the Sencore with certain settings of cutoff, then it is clear the tube is gassy. If cutoff responds normally, then the tube is quite possibly good.)

Tonight was by no means conclusive, and I'm going to continue to assume the tube is a dud. That said, I may get a pleasant surprise when I get the tube on the Sencore, and eventually (God willing) a working 15 inch chassis.

Thank you again Dwight!

Last edited by benman94; 10-06-2017 at 11:03 PM.
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Old 10-07-2017, 09:57 AM
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I've determined how Dwight got the low readings for emissions by replicating them; he accidentally connected the G1 lead from the B&K to G2, not G1.

Some photos of the chassis and jug:


Last edited by benman94; 10-07-2017 at 10:01 AM.
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Old 10-07-2017, 10:29 AM
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Any ideas on what causes that weird swirling pattern on some color CRTs? I had a 21CYP22 with the same damn thing. It didn't seem to alter the picture in use, but it looked like hell when the set was off.

Perhaps RCA continued their prewar policy of selling "lesser" CRTs to competitors and holding the best for their own sets.

The 15GP22 in this set was built in the 13th week of '54.
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Old 10-07-2017, 12:33 PM
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The getter above the blue gun looks a bit odd to me, almost like a small portion of the center has flaked away from the glass. It isn't white though, everything is still a dark grey/black color:



The other two getters look fine, and actually a deal bigger than the getters on the tube in the CT-100 I sold:

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Old 10-07-2017, 03:49 PM
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Impressive! that chassis is a beast! Is the circuitry much different from the CT100, or did Westinghouse not get innovative?

I assume the chassis is copper, like my h22t155, or is that rust?

I have seen drying patterns in some early kasil settled phosphor tubes, but not rings like that... could that be a moire pattern perhaps generated by poor contact of the silk screen during the screening of one of the phosphor colors? Seems likely that RCA would sell less than perfect tubes to competitors.

Perhaps the getter above the blue gun was the first one flashed after "pinch off", in a fairly poor vacuum.

Looks like a very fun project.

jr
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Old 10-07-2017, 04:16 PM
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Quote:
Originally Posted by jr_tech View Post
Impressive! that chassis is a beast! Is the circuitry much different from the CT100, or did Westinghouse not get innovative?

I assume the chassis is copper, like my h22t155, or is that rust?

I have seen drying patterns in some early kasil settled phosphor tubes, but not rings like that... could that be a moire pattern perhaps generated by poor contact of the silk screen during the screening of one of the phosphor colors? Seems likely that RCA would sell less than perfect tubes to competitors.

Perhaps the getter above the blue gun was the first one flashed after "pinch off", in a fairly poor vacuum.

Looks like a very fun project.

jr
Totally different ball of wax compared to a CT-100. Difference demod (R-Y and B-Y), but the mixing is done CT-100 style with seperate triodes for RBG in the adder section and a triple diode clamp.

No traditional PLL like the RCA, nor the shock excited crystal approach of the 15 inch GE. Just a color hold control up front. The hue is on the rear panel like on the GE. What were they thinking?

Totally different HV and focus section compared to the RCA. Uses three 3A3s in a doubler arrangement for the ultor and a 1X2? for the focus. According to an old post on the H840CK15 from Folsom, this set has the most stable HV of all the 15 inchers.

Twin 6BG6Gs drive the flyback, compared to the 6CB5s and 6CD6s used in other sets.

The set also makes use of the unusal 6BK5 tube, a minature tube ultimately derived from the 6Y6, 6W6 family. One for audio output (about 2ish watts) and one to drive the delay line.

The audio section in particular leads me to believe this was the brainchild of a Westinghouse engineer and not some copy cat chassis; Westinghouse was one of the only manufacturers using the 6BK5 and 6BN6 combination to lower parts count. I think Zenith may have used it too.
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Old 10-08-2017, 01:59 PM
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Quote:
Originally Posted by jr_tech View Post
Impressive! that chassis is a beast! Is the circuitry much different from the CT100, or did Westinghouse not get innovative?

I assume the chassis is copper, like my h22t155, or is that rust?

I have seen drying patterns in some early kasil settled phosphor tubes, but not rings like that... could that be a moire pattern perhaps generated by poor contact of the silk screen during the screening of one of the phosphor colors? Seems likely that RCA would sell less than perfect tubes to competitors.

Perhaps the getter above the blue gun was the first one flashed after "pinch off", in a fairly poor vacuum.

Looks like a very fun project.

jr
The chassis is copper plated.

I couldn't resist the temptation to retest the tube today with the Beltron. Dave Pike will be coming over with his Sencore CR-70 to check for cutoff later this week.

Red:


Blue:


Green:


I've never seen a tube this closely matched on all three guns, so I'm inclined to think it's gassy, but I got no indication of gas while testing it (blue or purple glow between the cathode and first grid) or with the tesla coil...

I need to find someone in the area with a working 15 inch chassis.
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Old 10-08-2017, 02:55 PM
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Very curious Ben.

Meter readings seem suspicious just like a gassy 15G I have. But the fact that you cant get any neck glow, even with your Tesla coil makes me believe the tube is NOT gassy. I have never seen a gassy tube that failed to give a purple glow with a Tesla coil.

Your getters look just like the ones in my aforementioned 15G (shiny and black) which is gassy, but my tube glows like a neon sign with my Tesla coil.

CR70 cutoff test should prove it one way or the other.
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Old 10-08-2017, 02:59 PM
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Quote:
Originally Posted by benman94 View Post
Any ideas on what causes that weird swirling pattern on some color CRTs? I had a 21CYP22 with the same damn thing. It didn't seem to alter the picture in use, but it looked like hell when the set was off.

Perhaps RCA continued their prewar policy of selling "lesser" CRTs to competitors and holding the best for their own sets.

The 15GP22 in this set was built in the 13th week of '54.
Must be a manufacturing defect, right? I don't see how it could happen afterwards. I thought the imperfect CRTs ended up in test jigs, but was there ever a 15-inch test jig? I'm guessing not.

Good luck, I really hope your picture tube is functional.
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Old 10-08-2017, 03:06 PM
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Quote:
Originally Posted by ohohyodafarted View Post
Very curious Ben.

Meter readings seem suspicious just like a gassy 15G I have. But the fact that you cant get any neck glow, even with your Tesla coil makes me believe the tube is NOT gassy. I have never seen a gassy tube that failed to give a purple glow with a Tesla coil.

Your getters look just like the ones in my aforementioned 15G (shiny and black) which is gassy, but my tube glows like a neon sign with my Tesla coil.

CR70 cutoff test should prove it one way or the other.
What tesla coil do you use? Any tesla coil of sufficient power should show gas... now I'm going to check and make sure it's working properly with an unused CFL...
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Old 10-08-2017, 06:28 PM
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The fact that you have seen the same sort of swirl on two different tube types that used different methods of application is really interesting. I have never seen anything like this.

In the 70's, Sylvania came up with a brighter phosphor slurry that was thicker than usual. Motorola had trouble using the thicker slurry because of broad swirl marks, but they were faint and only showed up when the tube was lit. Engineering staff were commandeered to take two identical 19 inch sets (except for old and new slurry) home and get unprompted comments from their families to find out if anyone could see the swirls as well as the difference in brightness.
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Old 10-08-2017, 06:32 PM
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Can you hold up something with a contrasty pattern to the tube and see if the reflection is distorted? Wondering if the swirl is a defect in the glass phosphor plate.
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Old 10-08-2017, 06:42 PM
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Wayne,

I held a sheet of log paper up to the tube. It was sort of hard to see, given that there was a second reflection from the front of the jug itself, but no, the reflection of the pattern from the inner glass phosphor dot plate was not distorted.

The swirling is definitely the phosphor itself.

Last edited by benman94; 10-08-2017 at 07:41 PM.
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Old 10-09-2017, 11:18 AM
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About Tesla coils and CRTs. I have a Tesla coil or three. I used them to start discharges
with microwave generators to make Fluorine or Oxygen atoms for my research.
They are exactly like the pictures I see offering the CRT tester ones in ebay.

But ... is using one to test a 15GP22 in a CT-100 (in the set) dangerous to the
parts of the set, like the yoke or purity magnet? I would of course disconnect everything.
The CRT itself is immaterial ... its red gun is truly dead.
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Old 10-09-2017, 11:59 AM
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Quote:
Originally Posted by dtvmcdonald View Post
About Tesla coils and CRTs. I have a Tesla coil or three. I used them to start discharges
with microwave generators to make Fluorine or Oxygen atoms for my research.
They are exactly like the pictures I see offering the CRT tester ones in ebay.

But ... is using one to test a 15GP22 in a CT-100 (in the set) dangerous to the
parts of the set, like the yoke or purity magnet? I would of course disconnect everything.
The CRT itself is immaterial ... its red gun is truly dead.
For testing the CRT for gas with a Tesla coil, I removed the purity coil assembly and yoke. On the Westinghouse chassis this is extremely fast. Loosen four nuts, slide everything back and you're done.

I removed them simply because it is easier to see discharge with more of the neck exposed.

I would keep the Tesla coil away from the base as much as possible; check up by the convergence and focusing electrodes. A Tesla coil of sufficient power can burn out a small incandescent light bulb; I imagine a tube heater would be fundamentally no different.

If your tube is gassy, it will be very apparent with the Tesla coil.

Another good test for gas is a Sencore CR-70. Play with bias setting. At sufficiently low bias voltage the meter should peg; the cutoff control fails to control the beam current like normal if the tube is gassy.

Actually, with a sufficiently gassy tube, the voltages from the Sencore are sufficient to strike the gas and cause discharge between the cathode and grids one and two.

See this post for an admittedly poor picture of what I'm talking about:

http://mail.videokarma.org/showpost....0&postcount=16

I would be very curious to know if you can see the faint purple pink glow between the red cathode and first or second grid in your tube Doug.

Last edited by benman94; 10-09-2017 at 12:03 PM.
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