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Old 09-18-2007, 11:24 AM
Pete Deksnis's Avatar
Pete Deksnis Pete Deksnis is offline
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I strayed over into the audio threads...

and came across a cool thread about heat. Dear to my heart it is, and so I paste my response here fer u'all:

Intriguing thread idea...

Although my high-power tube audio days are over (Citation IV and V), and have shifted to vintage color TV (36 tubes in a CT-100; 410 watts at 115 Vac) I do get concerned about stress on the old sets anytime I run one for more than a few minutes, summer or winter. Never worried about the 12AX7's in my Citation preamp, but like the Citation V then, I still gauge equipment stress indirectly by the warmth of the power transformer: if it's quite hot to the touch, it's been on too long in that given environment. It's a subjective assessment to be sure, but one I've used over the years to coddle important tube-based electronics. My philosophy here is steeped in troubleshooting high reliability tube-based military electronic systems in my youth; you could grab any power transformer that was in 24/7 service and just have it warm to the touch. Two basic reasons: it was designed (over-designed) to run that way and there was forced-air cooling everywhere (even refrigerated when necessary).

HK Citation amps and preamps were very well designed and built, as they used late fifties-style military terminal-board construction and IIRC the PA stages ran in AB, so the load on the power transformer and supply components was not constant. Nevertheless, in the heat of summer or a hot apartment or home, I did and still do the transformer-heat touch test. And finally, the RCA CT-100 was not designed to mil-spec by a long shot, and so the touch test is more useful today than it was for my Citations.


Pete
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Old 09-19-2007, 05:04 PM
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stromberg6 stromberg6 is offline
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Hi Pete: I know what you mean. I run three tube stereo systems, and the McIntosh C-20 needs new 12AX7's. Checking costs, I find that the tubes I would like to use are way expensive, so I will use others. 6SN7's are also VERY dear. I am also now spending more of my hobby funds on vintage TV restoration. I have a blonde "7" to restore, and a recapped DeLuxe 5 to put back together. Great therapy.
BTW, I have seen your post about the video input interface article, and only have the first page. I am wondering if the same circuit that works with the CTC-2, and 2B will also work with a CTC-4, etc.
Loved the pix from the ETV convention.
All the best,
Kevin
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Old 09-19-2007, 09:36 PM
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why not install fans?
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Quote:
Originally Posted by TVTeufel


Another idea.....instead of expensive anti-psychotic drugs, let's provide schizophrenics with dummy bluetooth headsets. They'll easily blend into the crowd, although I suspect their "conversations" would be far more rational than those of the typical Wal-Mart shopper.

Ron
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Old 09-19-2007, 11:09 PM
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Last edited by andy; 12-07-2021 at 02:07 PM.
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Old 09-21-2007, 05:10 PM
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Pete Deksnis Pete Deksnis is offline
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Quote:
Originally Posted by stromberg6 View Post
BTW, I have seen your post about the video input interface article, and only have the first page. I am wondering if the same circuit that works with the CTC-2, and 2B will also work with a CTC-4.
Kevin: just completed a search for those CTC4 instructions but only found the same pages you have. There were substantial differences between the CTC2 and CTC4 interfaces. If you are interested in 'jeeping' (thanks Fred!) a CTC4, perhaps we can go back to my original source and get you a copy. Let me know.
Pete
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Old 09-21-2007, 06:26 PM
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Thanks Pete. I will go over the schematics for all three chassis to compare the video detector and first video stages. Perhaps the circuit in the article you have can work with the 4 if the output of the interface circuit can be matched to the 6CL6 1st video stage. It could be a rewarding project. Even though the 4 is narrow band, the color of the 21AX is super. I can't post a screen shot here, but can send one to your address if that's ok.
Kevin
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