Westinghouse H840CK15

[jr_tech]

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

[benman94]

Originally Posted by jr_tech

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.

[benman94]

Originally Posted by jr_tech

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.

[ohohyodafarted]

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.

[benman94]

Originally Posted by ohohyodafarted

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...