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All SIT 50W+ Single Ended Amp (beta)
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Old 20th October 2020, 12:08 AM   #41
alexopth1512 is offline alexopth1512
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Nice... any news on this? My 182Es is on the way...
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Old 20th October 2020, 04:31 PM   #42
plasnu is offline plasnu  United States
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All components are here except input transformers from Cinemag (12 weeks waiting time so far), and most of them are attached to the case and liquid cooling heatsink. Water lines are also ready to go (not tested). I just need to finish wiring, but I have been lazy these days... I will start finishing this when I receive transformers. Well, I'll call David@Cinemag today.
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Old 20th October 2020, 05:01 PM   #43
plasnu is offline plasnu  United States
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alexopth1512, I remember that you're also trying to dissipate 150-200W from 2SK182ES.

I'm afraid that thermal resistance would be the bottleneck of the amp's performance, so I flattened the base plate of Tokin for better dissipation. You can see the flatness using a bright light and a ruler, and you'll find the manufacture case is warped enough to make you paranoid. I flattened it with a whetstone. I also used thermal grizzly and alumina sheet for the best possible thermal resistance.

This would be a little overengineering, but well, this is a hobby and I'm just having fun.
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Old 20th October 2020, 05:52 PM   #44
alexopth1512 is offline alexopth1512
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Yes!! I have already did that.. it was a known technique for us old in computers that we were smoothing the base of big heatsinks back then ti have better performance.
Just for your info, I manage fine with watercooling to remove 300W+ from (90V, 3.6A) from the FET. No problem on that anymore. With watercooling in big speed, we are at 44 C
And of course Arctic Silver 5
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Old 20th October 2020, 06:04 PM   #45
plasnu is offline plasnu  United States
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Join Date: Jan 2011
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A good news!

I had an electrical conducting issue possibly due to Arctic Silver 5 before, and since then I stopped using it. One of the FET on Aleph J smoked after 6 months without any reasons. Arctic Silver 5 may become electrical conductive after a while? They claim it is not electrical conductive, but they do not say it very strongly as the other products they sell. Please keep your eyes on it, and let us know if you find any issue.
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Old 20th October 2020, 11:53 PM   #46
alexopth1512 is offline alexopth1512
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Join Date: Sep 2020
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I had AS5 in a home hi end PC that was running for more than 10 years without any change. Had no issue ... But in any case you must be careful with the quantity, i apply only a small bit and this is enough to spread to the surface. Now I had no experience before with transistors, so I was creative... But I put only very minimal quantity.
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Old 21st October 2020, 07:42 PM   #47
plasnu is offline plasnu  United States
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I have never had any issues with AS5 on processors either. Yes, quantity may matter. When I checked the burned FET, alumina sheet was cracked, and FET and sink seem to have a direct contact via AS5. hmm...
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Old 21st October 2020, 07:56 PM   #48
alexopth1512 is offline alexopth1512
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How exactly do you mount the FET? i use direct contact with AS5 in the middle, no mica or anything and I check that pump that has the surface doesn't contact any metal. I haven't use the SIT yet I am on the IXYS TO-247, since SITs are still on the road...
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Old 21st October 2020, 09:56 PM   #49
plasnu is offline plasnu  United States
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Join Date: Jan 2011
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Mine is Aleph J with DIYAUDIO boards, not SIT either. IRFP240 is electrically isolated from heatsink via alumina sheet, then heatsink is grounded as a regular FW amp. Do you isolate both heatsink+FET from the ground? I do that often when I test amps, no isolation between FET and heatsink.
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Old 22nd October 2020, 07:46 AM   #50
alexopth1512 is offline alexopth1512
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Yes to have best conduct I do not isolate the pump from FET. But this is the first time I have build an amplifier, after 35 years..
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