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Old 12th August 2009, 12:16 AM   #1
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coldcathode's Avatar
Join Date: Jan 2009
Default Looking for curves for obscure tube

Been real busy working around the house until recently. I was sorting some of my collection and started with globe and st shaped tubes. I came across what appear to be NOS Tung-Sol 485' (4 of them). The only data I can find is make plate voltage of 180 and Mu of 12.5 or so. I am wondering if anyone has in their collection of data some curves? It appears this was a very little used tube. I am always up for a challenge and I was thinking a nice line stage using these might be nice.

Anyone got any further info on these?
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Old 12th August 2009, 12:22 AM   #2
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Tom Bavis's Avatar
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Location: Macedon NY
It's a Sparton number, don't know if anybody else used 'em. You could probably use the curves for 56, 76, 6P5 or 27 and be close enough.
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Old 12th August 2009, 01:41 AM   #3
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Location: West Virginia panhandle
I can't find any info on the 485, but I can offer this. I found an old Sparton radio chassis in the dirt at a flea market. I got it for $10. It had a bunch of globe tubes in it and I don't remember all of the numbers. The output tubes were marked National Union NX-483. They had a guarantee sticker from 1929! The NX483 turns out to be the same as a 183 which is an output triode that works like a 45 with a 5 volt filament. They sound really nice in a Tubelab SE.

It is possible that the 485 could be an NX-485 or could be similar to a 185. A quick Google search didn't turn up anything, but maybe some of the old radio sites may have some info.
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
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Old 12th August 2009, 01:19 PM   #4
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Thanks guys! I guess what I will do is try a simple gain stage and cathode follower and listen??

I come across a lot of interesting tubes using the "flea market" method. I have also found that showing interest as "something I know nothing about but would like to play with" gets the price much lower than giving away that I know about tubes. LOL

Quick question that I know both of you can answer,

What load resistance should I use if I know the Plate resistance from the little data I have?
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