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Any advice on 31 volt filaments on sweep tubes?	Reply
by WD7Z on November 3, 2008	Mail this to a friend!
I've bought some matched 31LQ6's instead of the 6LQ6's for my Swans. I'm sure I don't need to say why. I can get a 25.2v transformer from radio shack to run in series with the 6.3v filament voltage easy enough. Feeding the 31v filaments in parallel and through a resistor seems like it would give the filaments the soft start they like as well as dropping the voltage to close to 31v. Am I on track or way off? Does anyone know what the filament current is on 31v filaments is compared to 6.3v? I don't know, but it seems like VA would be the same on both. I'd appreciate hearing any advice or suggestions on this subject. John WD7Z

RE: Any advice on 31 volt filaments on sweep tubes	Reply
by WB2WIK on November 4, 2008	Mail this to a friend!
31LQ6 heater rating is 31.0v at 450mA.

RE: Any advice on 31 volt filaments on sweep tubes	Reply
by WD7Z on November 4, 2008	Mail this to a friend!
So the VA is about the same. Thanks, Steve. I guess it was a silly question. It would be a pretty bright filament at 2.3A.

RE: Any advice on 31 volt filaments on sweep tubes	Reply
by WB2WIK on November 5, 2008	Mail this to a friend!
I didn't calculate it, I looked it up in the 1966 RCA Receiving Tube manual... But it does seem logical that the same VA would generate the same "heating."

RE: Any advice on 31 volt filaments on sweep tubes	Reply
by WA6HDZ on November 5, 2008	Mail this to a friend!
There are lots of tubes like this that were made for transformerless TV sets. These sets used tubes designed for a common filament current (typically 450 or 600 mA) and connected the filaments in series to the 120 VAC AC line. Otherwise the tubes are the same as the 6.3 or 12.6 volt versions and can work well in amplifiers.

RE: Any advice on 31 volt filaments on sweep tubes	Reply
by W7ETA on November 5, 2008	Mail this to a friend!
http://www.nj7p.org/Tube4.php?tube=31LQ6 Here if you can't find it on NJ7P: http://scottbecker.net/tube/sheets3.html

RE: Any advice on 31 volt filaments on sweep tubes	Reply
by AD4U on November 6, 2008	Mail this to a friend!
You can run 4 of these tubes in series directly from the 120VAC line. This is how they were intended to be used in televisions. Dick AD4U

RE: Any advice on 31 volt filaments on sweep tubes	Reply
by WD7Z on November 6, 2008	Mail this to a friend!
I see no objection to taking the 6.3v filament transformer to a 25.2v transformer and feeding the 31v filaments in parallel and through a resistor. 40 bucks after postage for a matched pair, same brand and date code is not too bad at all for xLQ6's from a reputable dealer. I've added those tube links to my favorites. Thanks, everyone. John WD7Z formerly W7FRS

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