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PL 519 electrical characteristics

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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
 
<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?
 
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.
 
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 ...
 
good experience

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
 
.....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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500 Watt PA with PL519

An externally hosted image should be here but it was not working when we last tested it.


This is the circuit of a 500 watt linear amplifier, based upon a design by Frits Geerligs, PA0FRI, who has his own homepage at 404 De pagina is niet gevonden. The circuit uses four PL519 TV line output valves in a very simple circuit that will deliver over 450 watts at 3.5 MHz (350 watts at 30 MHz). PL519 (40KG6A) is a more robust replacement for the earlier PL509 (40KG6) tube............Read more
 
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