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The adventure begins! Have you determined at all if this could be a dot-sequential prototype rather than early NTSC?
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My two cents. Pete |
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Last edited by MelodyMaster; 06-16-2011 at 05:42 AM. |
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As Steve McVoy indicated, there are competing reasons for a post-1952 tube to be in this set. Also, as been stated earlier in this thread, there is not a scintilla of visible evidence that the CRT socket had 4-or-so kV on the convergence element (pin 13) for an extended period. Still, there are no final conclusions. Perhaps this chassis will turn out to be from Hazeltine Corp.; they were located in the same general area as RCA Labs and where Harry Poster now has his business. The quest goes on... Pete Last edited by Pete Deksnis; 06-16-2011 at 10:39 AM. |
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This is kinda like findin' Gottlieb Daimler's heretofore unknown SECOND prototype of his 1886 car under a tarp in a dry barn somewhere...
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Benevolent Despot |
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so is the face of that tube a greyish or a little greenish in color. More like the color of the early 15GP's or more the color of the 21axp's? I wonder if the 1b3's meant the tube was designed to have lower beam current. Too bad there ain't a Sam's you could order for that chassis.
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Yes you can call me "Squirrel boy" |
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It looks greenish to me, kinda like the 21AXP22 in my CTC-2B. I have it parked right next to the CTC-4 at the moment, and it's very obvious the difference when viewed right on. The screen on the 2B almost glitters, while the one in the 4 just looks like plain paper.
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Evolution... |
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From what I learned by using the CR-70, a tube with air will peg the needle after advancing the cutoff control beyond a certain point. You reach the ionization point of the gas inside, and then you get full conduction. Exactly that happened with the 21AXP22 that was in my Director 21, purple neck to boot. But this one is fully variable throughout it's entire range, and the needle rises slowly as it warms up just like it should. So I'm optimistic about it, but we won't know until some HV can be applied.
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Evolution... |
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I think the next question is not if this set can be made operational but IF it should be.
If it's an RCA Prototype it truly is a signifigant piece of history, replacing capacitors and other components would seriously compromise it's historical value IMO. |
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I have mixed feelings about whether to restore it and I can think of good arguments for both sides.
Personally, I would find it hard to resist making it work. It was designed as something to be used, after all, not a museum piece. I would soothe my conscience by doing nothing invasive, restuffing paper caps as well as electrolytics, maybe even finding resistors that look more period-correct. Ideally, when it was done, it would look the same (at least to a casual eye) but WORK as the designers intended. Just my $0.02. Phil Nelson Phil's Old Radios http://antiqueradio.org/index.html |
Audiokarma |
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Here's my take: It is a museum worthy piece, therefore it belongs in a museum. For that reason, I am considering placing it at the ETF once I am done with it. I have always been of the mind that if the set actually works, no one is going to care what's 'under the hood', since 9 times out of 10 it would not have worked on original capacitors anyway. No one walks into the ETF and says about the Model 5: "you know that thing would be much better non-functioning and with original caps". I don't think so. It's a much better thing to see it in operation, it blows away any thought of keeping it original once you see something on screen. Lastly, I may not have to change anything in the first place. The chassis has what appear to be aerospace grade metal-film capacitors, so it may not need total replacement of the caps. They are not prone to leakage and breakdown like wax/PIOs are, so we'll see if they are any good. The lytics will be restuffed, but thankfully they are all mounted on wafers and secured to the chassis with screws. They will be easy to do.
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Evolution... |
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Congratulations! I agree with your statements one-hundred percent. Also, once you have an operational platform, Pete might consider performing comparitive colorimetry measurements on your CRT. Last edited by TubeType; 06-19-2011 at 03:48 PM. Reason: Spelling Correction |
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I think there's historical value in being able to see just what a dot-sequential or proto-NTSC electronic receiver was capable of. We've now been able to see what the CBS sets were capable of for quite a few years, but when they first came back to life it was quite a revelation.
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I agree with Phill's suggestion for how to go about electronically restoring it.
Better to keep it looking original if you restore it IMHO. Tom C. |
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If it were mine, I'd want to restore it to working condition using reliable modern capacitors. Save the removed parts.
But, I would take multiple high resolution detailed digital photos of the entire chassis as documentation history of the set. You are now part of this TV's history. Carl
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