**GRUMPY**
Administrator/The Boss
Classic Radio Operator Olde Timer 8220 [/color][/center]
"The King of Ping"
Posts: 4,342
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Post by **GRUMPY** on Dec 26, 2005 17:58:53 GMT -5
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Post by Tombstone (R.I.P.) on Oct 16, 2008 5:38:31 GMT -5
Here's a link for a site that lists all American made tubes and their function. www.classiccmp.org/rtellason/tubes.html. If this link brings you to the main page you'll have to scroll down to find the chart I'm talking about and click on that site and I forget the name of it but I found it by doing it that way. When I put it in my favorites list the title now is "Tubes" so the link might take tou directly to the chart. I have a lot of television tubes here that I don't need and will separate them from my radio tubes but I'm not familiar with most of them so I needed to find a chart that lists tubes by number and function. Once I get the TV tubes separated from the ones for radio I don't know what to do with them, of course they'll all have to be checked and I hate to just throw them away, I'll end up with quite a few. I know that Antique Electronic Supply wil buy used tubes but I'll have to get on their site and find out what the procedure for that is. Tombstone
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Post by 238 on Oct 16, 2008 22:50:12 GMT -5
Tombstone, i could not get to come up. Please send me the site. 238
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Post by swamp40 on Oct 17, 2008 3:53:12 GMT -5
ME either, please send also
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Post by swamp40 on Oct 17, 2008 4:09:13 GMT -5
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Post by Tombstone (R.I.P.) on Oct 17, 2008 7:17:06 GMT -5
I was afraid of that, when I saved the site to my favorites the name of it is Tubes on the list. I just went on the site and it's Roy J. Tellason's Home page or you can bring up Roy J. Tellason's parts page and scroll down to the bottom and you can click on vacuum tubes. I found it with a Yahoo search. I typed in vacuum tubes listed by number and function. I don't know why that url won't work, it's at the top of the Yahoo page when I click on Tubes in my favorites list. I hope you guys can find it!
Tombstone
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Post by Marc on Oct 17, 2008 16:42:49 GMT -5
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Post by Tombstone (R.I.P.) on Oct 17, 2008 21:15:04 GMT -5
That's the link allright but they say it won't work. I've been on it for the last two hours sorting out the TV tubes from my radio tubes. I'll be selling some to Antique Electronic supply and so far I have about 100 tubes going to the trash and I haven't scratched the surface of what I have.
Tombstone.
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Post by Sonwatcher on Dec 13, 2008 10:59:44 GMT -5
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Post by 321 treeclimber on Jul 7, 2019 7:37:29 GMT -5
8950 need 2 321
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 7, 2019 10:18:15 GMT -5
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Post by Night Ranger on Jul 7, 2019 12:57:34 GMT -5
6LF6 tubes are similar to 8950 tubes, but the filament has to be rewired for the different tube filamanet voltage. 8950 tubes have a 12 volt filamanet and 6LF6 tubes have a 6 volt filament. The tube pinouts are identical. Night Ranger
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 7, 2019 16:51:47 GMT -5
6LF6 tubes are similar to 8950 tubes, but the filament has to be rewired for the different tube filamanet voltage. 8950 tubes have a 12 volt filamanet and 6LF6 tubes have a 6 volt filament. The tube pinouts are identical. Night Ranger Another alternative would be the 6LB6. Also a 6 Volt tube, and a heck of a lot cheaper than an 8950. Bear in mind that the output power will probably be a little bit lower with these tubes. But that won't make much difference on the other end. If the amp has an even number of tubes, you can wire the filaments of each pair of 2 in series and then place those across the 12V source. Not too big of a change.
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Post by 321 treeclimber on Jul 7, 2019 21:02:49 GMT -5
Its a skipper 300, 4 tubes. 1 and 3. Is it a big job to rewire ?
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 7, 2019 21:34:58 GMT -5
Its a skipper 300, 4 tubes. 1 and 3. Is it a big job to rewire ? No, actually it should be easy. You have 4 tubes, so you just have to wire two pairs of tubes to have the filaments in series. Not tough at all.
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Post by 321 treeclimber on Jul 7, 2019 21:55:49 GMT -5
Sounds good, where do i start?
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Post by 2600 on Jul 7, 2019 22:10:43 GMT -5
Palomar used tubes with 6.3-Volt heaters in some Skipper production.
The 8950 version has the 12.6-Volt AC feeding one heater pin of each of the four tubes, and the other heater pin is grounded at each socket. Commonly called "parallel connection".
To use four 6LB6, 6KD6, 6LF6 or other 12-pin tube, you choose two pairs of the four sockets. I use the front two, and the rear two as pairs.
One socket gets the "hot" 12-Volt wire detached. The other tube of that pair gets the ground unhooked from it. A wire is now added from the loosened-up pin on one tube the the now-loose pin on the other socket. One tube of this pair now has the 12-Volt wire feeding it, the other tube has a wire from the first tube feeding the "hot" side where the original 12-Volt wire was pulled.
Yeah, pictures would be nice. Pin 1 and pin 12 are the tubes' heater connection. Since I'm not sure which numbered pin is hot or ground on the original hookup, there's no way to be specific with the pin numbers for this trick. What you end up with is two pairs of tube heaters in series, splitting the 12.6 Volts 50-50 between them.
We always add a .01uf disc capacitor going to ground to the tube pin that got pulled from ground. One for each pair. Might not make a difference. Just good engineering practice.
Doing it this way may make it necessary to use tubes from the same factory, so the heaters will warm up together. If one tube in a pair gets more than half the AC heater voltage, it could pull excess current when you're keyed down. And if that makes this tube overheat, it will fail prematurely.
But that's the reason to keep a close eye on the tubes after completing this kind of repair *OR* modification, both. If one tube's anode surface begins to "cherry" while the others are still dark and gray, the job is not yet complete. An amplifier containing an out-of-balance tube is not a repair, it's a time bomb.
73
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Post by 321 treeclimber on Jul 8, 2019 7:32:27 GMT -5
Time bomb, 10-4. Well yet another hurdle. Sounds like fun. I've been successful so far....321
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Post by 321 treeclimber on Jul 8, 2019 7:34:24 GMT -5
Which alternative tube do you reccomend?
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 8, 2019 18:22:07 GMT -5
Which alternative tube do you reccomend? The 6LB6 seems to be the most cost effective solution from what I'm seeing.
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Post by 321 treeclimber on Jul 8, 2019 19:20:17 GMT -5
Then thats what im doing. Where can i get good tubes and a reasonable psychiatrist? 321
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 8, 2019 20:47:12 GMT -5
Then thats what im doing. Where can i get good tubes and a reasonable psychiatrist? 321 Google search, Ebay? It pays to shop for the best deals.
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Post by 321 treeclimber on Jul 8, 2019 22:31:38 GMT -5
Can i get the 6lb6s brand new? Still being made?
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Post by 2600 on Jul 9, 2019 0:07:17 GMT -5
Haven't been made for years. Any "new" tube is new old stock.
Hard part is finding three that match each other for the final stage. For an amplifier with four tubes I would buy five. More than once we have seen a new tube flash blue and go "SNAP!" the third or tenth or thirtieth time it's keyed. That fifth tube will come in handy to take its place.
The brand name on a carton, or printed in color on the tube is put there by a wholesale distributor, not the factory.
The factory shipped tubes in bulk cases of 144, with only the type number printed on it. The bulk tubes got the name brand printed on at the next step, the wholesale distributor. If the GE sales division ran out of 6L6 tubes (for example) they might get told by the GE factory that the next production run for that number is weeks away. The wholesale division would then buy bulk tubes on the open market, made by any (potential) competitor. If they found enough tubes to fill their orders, but were made by RCA, the "GE" name still got printed on the tube before it was stuffed into a carton with "GE" printed on the outside.
Just one example, but a sales company's incentive is to make sales. The factory's incentive is an orderly, predictable production schedule. Rather than tell their customers "you gotta wait", the sales division would fill their orders any way they could, buying unmarked tubes in bulk on the open market.
Just don't trust that printed brand name to make tubes match properly. Who made the tube will be more important for matching than who sold it.
An amplifier runs this kind of tube harder than the color TV circuits it was designed for. The good ones hold up, and the occasional weak sister is just a routine risk. Tube testers usually can't predict this.
73
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Post by 321 treeclimber on Jul 9, 2019 4:55:00 GMT -5
Got it. I found a site with the palomar name on it claiming "tube sets" and conversion directions. I will call them today. Its titled "palomar engineers"
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Post by 321 treeclimber on Jul 9, 2019 8:15:31 GMT -5
Escondido, cali.....here i am in NY READY FOR ACTION AND THEIR STILL SLEEPIN !
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 9, 2019 10:40:43 GMT -5
Can i get the 6lb6s brand new? Still being made? Not in the USA. But there may be Russian or Chinese made tubes that are brand new. I tend to be suspicious of those though.
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Post by 321 treeclimber on Jul 9, 2019 11:59:47 GMT -5
Just need to locate tubes and im off and running.
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Post by cbrown on Jul 10, 2019 12:31:32 GMT -5
You can always get matched pairs of 6LB6 tubes from RF Parts.
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Post by 321 treeclimber on Jul 11, 2019 10:42:23 GMT -5
Is that the go to spot? I've had my fill of not-so-great on-line shops.
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