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#26 pre amp
#26 pre amp
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Old 20th March 2013, 04:52 PM   #2601
merlin el mago is offline merlin el mago
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I haven't space for SSHV2 in the box bought by mistake to HIFI2000
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Old 20th March 2013, 04:58 PM   #2602
vgeorge is offline vgeorge  Greece
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#26 pre amp
OK, disconnect the gyrator and use a resistor to drop your 200V to 150V, it should be something around 800 to 900 ohm 10W, and see what is going on, on the scope.
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Old 20th March 2013, 05:03 PM   #2603
merlin el mago is offline merlin el mago
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I have 307VDC in place of 200VDC
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Old 20th March 2013, 05:06 PM   #2604
stajo is offline stajo  Sweden
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#26 pre amp
Maybe you can also try add a big cap between gyrator and 1660. With minus to ground, as a filter cap.
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Old 20th March 2013, 05:09 PM   #2605
merlin el mago is offline merlin el mago
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Quote:
Originally Posted by stajo View Post
Maybe you can also try add a big cap between gyrator and 1660. With minus to ground, as a filter cap.
Thanks stajo, I do the measurements before the LL1660 so I suspect the problem is before the LL1660, Thomas Mayer told me not necessary the cap for this OPT in this configuration.
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Old 20th March 2013, 05:15 PM   #2606
stajo is offline stajo  Sweden
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#26 pre amp
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Originally Posted by vgeorge View Post
around 800 to 900 ohm 10W, .
How did you count. I would say like 10 k half a watt.
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Old 20th March 2013, 05:17 PM   #2607
merlin el mago is offline merlin el mago
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Quote:
Originally Posted by vgeorge View Post
OK, disconnect the gyrator and use a resistor to drop your 200V to 150V, it should be something around 800 to 900 ohm 10W, and see what is going on, on the scope.
Quote:
Originally Posted by merlin el mago View Post
I have 307VDC in place of 200VDC
Quote:
Originally Posted by stajo View Post
How did you count. I would say like 10 k half a watt.
Hey guys I ned to drop 307VDC to 150VDC, who knows the reistor value?
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Old 20th March 2013, 05:17 PM   #2608
vgeorge is offline vgeorge  Greece
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#26 pre amp
Quote:
Originally Posted by merlin el mago View Post
I have 307VDC in place of 200VDC
Then find a way to drop your voltage and test without the gyrator.
Listen also to Stajo. Put a cap temporarily between gyrator and transformer, other leg to ground to see if something changes.
These are the tests I would make.
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Old 20th March 2013, 05:19 PM   #2609
iko is offline iko  Canada
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#26 pre amp
I would recommend that you do not try to "patch" it. Stop for a moment, and think of a proper solution.

For instance, if you want to use your output transformer, this is what you can do. Use a VR150 tube to get 150V at the transformer. Feed the VR150 tube with a DN2540 as a CCS set on 35mA max. Feed the DN2540 CCS with filtered 200V DC.
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Old 20th March 2013, 05:19 PM   #2610
vgeorge is offline vgeorge  Greece
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#26 pre amp
Quote:
Originally Posted by stajo View Post
How did you count. I would say like 10 k half a watt.
You are right, I miscalculated the current!
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