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Old 27th May 2012, 08:50 PM   #791
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I never experimented with PL36 in RF power stage , but I use it in my Futterman OTL ( triode connected ) a long time ago, about 8 years without any problem it's really a good tube, and in the last 7 months in an Circlotron OTL triode connected too but with AC coupling driver , with 10 PL36 in each channel I have output impedance of 1.2Ω which is pretty good result .

Last edited by Dimitris AR; 27th May 2012 at 08:53 PM.
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Old 27th May 2012, 09:17 PM   #792
banat is offline banat  Serbia
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Dimitris
That`s nice results
Have attention on Russian 6p13c (6p13s) tube , it is same as EL36 tube , it`s cheap tube but even more rugged as any European couterpart .
BTW , for once try DC coupled driver stage , bipolar suplyed , it`s worth !
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Old 27th May 2012, 10:01 PM   #793
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Thanks banat .Yes , good idea , I will try 6p13s in the next OTL project with DC coupling driver to see the differences , it's difficult to try it now because there is no space inside the amp at all for extra power supplies .
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Old 26th June 2012, 09:22 PM   #794
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Hmmm....

Interesting. Ive Never seen a PL509/19 with a failed cathode-connection link, and believe me, Ive overloaded severely many a PL509 over the years!....

Ones I'm using at the moment, Ive pretty well hammered many times and have now been used everyday for must be 6 months or more....
(Mozener, Triode-connected as described earlier in this thread)

Ive a couple of different make ones running, Two NOS ones and a couple of quite well used ones....

--Then again, I don't use 'em in RF Linears where flash-over/Arcs are more 'expected'!!

Nothing wrong with PL/EL509/19, and more linear than the small PL36 too....
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Old 27th June 2012, 09:05 AM   #795
banat is offline banat  Serbia
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Hi Alastair E !

Yes my observation ( and not only mine ) & experience was made driving PL519/EL519/PL509/EL509 tube on the edge of endurance , 1,7 Mhz , AM , RF class C with B+ up to 1,5 KV , or using this tubes for AF modulator (AF amplifier ), class B , with B+ of 800 V .
For example : driving PL519 with up to 1,5 KV on the plate only very small out of resonance point lead this tube to flash over of internal cathode to tube pin link .
After I destroyed this way bunch of PL519 I replace this TV tubes with suitable RF power tubes like GK71 or GU 13 and have no more problems.
Best Regards !
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Old 31st July 2012, 07:50 PM   #796
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Time for another try.

First one grew out of the box.

This time the PSU goes into a 19" 6H box.

Click the image to open in full size.

If it wonŽt fit this time iŽll give up.

The RIFA caps is tight fit in this box so who nows .
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Old 31st July 2012, 08:13 PM   #797
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Quote:
Originally Posted by flatheadmurre View Post
Time for another try.

First one grew out of the box.

This time the PSU goes into a 19" 6H box.



If it wonŽt fit this time iŽll give up.

The RIFA caps is tight fit in this box so who nows .
Here's a little trick if you are using toroids:

You can stack them if you have a longer bolt to hold on to them. It works best if one is on top and maybe the other two below. You may have to play with phasing of the AC mains so that the magnetic leakage is helpful rather than harmful to the transformer cores.

The other thing is to make sure you use a stainless non-magnetic bolt! A regular steel bolt represents a magnetic short of sorts to the toroid and will heat up a lot hotter than the transformer, no matter if the manufacturer of the transformer supplied a steel bolt, don't use it.
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Old 31st July 2012, 08:23 PM   #798
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Last time i had to hammer it togetter with a large sledgehammer.

And it took about 2hr to disasemble enough for tweaking .

Not going to happen again.

I usually have some plastic washers isolating the bolt through the transformer but if a stainless does it better iŽll try that.
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Old 31st July 2012, 08:24 PM   #799
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1/4-20 all thread?

Stainless Steel Threaded Rod - 1/4-20
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Old 31st July 2012, 08:53 PM   #800
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Originally Posted by TheGimp View Post
ThatŽll be hard to find here in the land of metric
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