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Old 11th October 2008, 06:34 PM   #1
Seraph is offline Seraph  United States
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Default PL 519 Electrical Characterstics

I have been testing some PL519's and getting some different results. I have been setting Vg1=-37V, Va=150V, Vg2=100V. Under these conditions for most samples Ia is anywhere between 25 ma to 35 ma, for one tube it was more than 70 ma. Tester is an AVO 163.

Could any recommend test setup parameters for a new PL 519?

Thanks
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Old 11th October 2008, 06:49 PM   #2
Fuling is offline Fuling  Sweden
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IIRC these tubes are known for being quite inconcistent.
http://www.tubes.mynetcologne.de/roe..._triode_e.html
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Old 11th October 2008, 09:11 PM   #3
EC8010 is offline EC8010  United Kingdom
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25mA to 35mA sounds pretty good to me. As the other respondent said, PL519 is not expected to be consistent - it's a TV line scan valve. The best test parameters are those you intend to apply in your amplifier...
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Old 11th October 2008, 11:06 PM   #4
Seraph is offline Seraph  United States
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<The best test parameters are those you intend to apply in your amplifier...>

And 40 ma is the design bias current for each PL519 in this amp. I'm finding of the 2 rows of 5, PL519's in each OTL mono block, only a few are operating near 40 ma. Most are biased between 18-25 ma and a couple between 70 to 80 ma. Replacing a single high or low conducting tube to match its mirror mate is hit-or-miss and buying 10 matched PL519's per amp is pricey at the moment. I have been wondering about the feasibility of a simple servo bias control to keep the bias point fixed.

Any ideas?
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Old 12th October 2008, 09:32 AM   #5
EC8010 is offline EC8010  United Kingdom
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I', guessing this is an OTL amplifier? Would it be possible to modify the design to bias valves individually? I take your point that obtaining that many matched valves would be expensive.
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Old 12th October 2008, 01:46 PM   #6
Seraph is offline Seraph  United States
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Yes these are OTL. Setting the bias points for each tube individually might be the easiest route. I will investigate that. Cathode resistors in this amp are 1.2 Ohm. So I will be needing some fine adjustment around this value possibly using a pot and a resistor in parallel. However, I have found that the PL519 cathode current can increase with age hence the need for a scheme to regulate the bias current rather than having to constantly monitor and adjust the bias current. A bad PL519 might be one that has its bias current increase with aging while at the same time its grid negative supply has remained fixed.
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Old 24th December 2008, 05:23 PM   #7
carolus is offline carolus  Belgium
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A bit late, i give my test results about PL519.
Project OTL T8 (upgraded to T12) ...(this is not a "product placement")
Test 47 x PL519 ("second hand" for a apple & egg) ..and 4 new tubes (never used).
Set points: Va=160Vdc, Vg=-40dc,Ufil=40Vac, Rcat=1ohm (1%),
G1 with 10k (stop), G2 with 100ohm to Va, G3 to cat
mV meter acros Rc
Scoop on Cathode (check oscilations & microinterruption)
Important: Test reading after 25min (temp-) stabilitation
Results: Ia between 26,8mA and ....92mA (one at 166mA) with approx a delta plus/min 2mA.
I think & prudent: it's difficult (unreal) to loock (and buy) after paired (identical caracteristques) PL519 (PL509)....even "new one" ....
I have no experience with "individual grid bias".
I hope that this can help (a little).
Allez, salukes.

To all, My best wishes for a good and fine Christmas and a great and safe end/new year .....let us hope ...
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Old 10th July 2010, 07:36 AM   #8
okk is offline okk  China
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Thumbs up good experience

Quote:
Originally Posted by carolus View Post
A bit late, i give my test results about PL519.
Project OTL T8 (upgraded to T12) ...(this is not a "product placement")
Test 47 x PL519 ("second hand" for a apple & egg) ..and 4 new tubes (never used).
Set points: Va=160Vdc, Vg=-40dc,Ufil=40Vac, Rcat=1ohm (1%),
G1 with 10k (stop), G2 with 100ohm to Va, G3 to cat
mV meter acros Rc
Scoop on Cathode (check oscilations & microinterruption)
Important: Test reading after 25min (temp-) stabilitation
Results: Ia between 26,8mA and ....92mA (one at 166mA) with approx a delta plus/min 2mA.
I think & prudent: it's difficult (unreal) to loock (and buy) after paired (identical caracteristques) PL519 (PL509)....even "new one" ....
I have no experience with "individual grid bias".
I hope that this can help (a little).
...

good experience
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Old 24th October 2010, 03:54 AM   #9
okk is offline okk  China
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i have measured about 10 pl519 or pl509. the source were different, NOS or used.
most of them, Ia were 90mA - 100mA.
but only one "NOS" pl509 from Japan was 60mA.
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Old 24th October 2010, 06:43 AM   #10
carolus is offline carolus  Belgium
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Quote:
Originally Posted by okk View Post
.....i have measured about 10 pl519 or pl509. the source were different, NOS or used ......
Hi Okk, good work & to know the (your) results (& deviations) ...
(results after minimum 20minutes warming up ?)
Fyi, my OTL (PL519) is nice in the musical-audio-running (and heat) ... and no problem (10Hr/day/365d) ...
Have a good time in China audio,
Allez, salukes & best regards,
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