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Old 25th February 2009, 04:39 PM   #21
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Magura, those sure are nice. I however l don't intend to
push mine hard only ~8 or 9 w or so. So I decided to salvage a couple of blown itfp240 mosfets and remove almost all the plastic.
Then sand the dead active device off exposing the copper base
and solder the jfet there. I hope the indium solder that melts
at ~97 c doesn't melt when I use the devices! I put a healthy
Irf260p in the picture besides my soldered Jfet.
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Old 25th February 2009, 07:03 PM   #22
Magura is offline Magura  Denmark
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97C may be a little on the low side, but time will tell.


I decided against low temp solder, in order to be able to abuse them


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Old 28th February 2009, 09:17 PM   #23
Magura is offline Magura  Denmark
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Quote:
Originally posted by flg
I haven't tried any soldering on these JFETs yet but on a daily basis I do such things with similar devices to heavy copper PCBs.

Please drop me an eamil, as I can't mail you.



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Old 1st March 2009, 07:03 AM   #24
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Done
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Old 2nd March 2009, 08:05 PM   #25
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Does anyone know the thermal resistance of that device from
case to heatsink?
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Old 3rd March 2009, 03:46 PM   #26
Magura is offline Magura  Denmark
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Quote:
Originally posted by woody
Does anyone know the thermal resistance of that device from
case to heatsink?

Of the JFET itself, or the ones I made?


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Old 3rd March 2009, 03:50 PM   #27
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Quote:
Originally posted by Magura



Of the JFET itself, or the ones I made?


Magura

ya have source of teflon tape , adequate for your "devices"

?
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Old 3rd March 2009, 05:16 PM   #28
Magura is offline Magura  Denmark
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Quote:
Originally posted by Zen Mod



ya have source of teflon tape , adequate for your "devices"

?
No, I use Kapton film


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Old 3rd March 2009, 05:40 PM   #29
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Quote:
Originally posted by Magura

No, I use Kapton film
Magura
Thickness?
Because I've only found 0.0015". Actually it was a while ago maybe it was 0.005" At 5000V/.001" dielectric strength, the thinner the better as long as you've checked for burrs and high spots etc.!
Why not use Kapton as the dielectric in your Quasi T-Clad developement project? It's high temp. It even comes with tape goo from Office Depot. Maybe you can get good high temp goo and make real High Performance thermal substrates. I'ld respond by e-mail but I've had to shift gears and think about all that T-Clad stuff in order to respond with a good answer...
While I'm thinkin 'bout it. I think you would have reasonable reliability (real good for the Magura/C/W normal levels) starting at 10W and possibly as high as 20W for that device. N.P. suggests 10W as a max? I would say 20W. N.P. also talks about the Vds vs Ids and load line linearity. That is where 2-3Vds is important. If your doin 10-20W at 3V thats 3.5-6+ Amps. This aint an F3 clone
But what could it be???
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Old 3rd March 2009, 05:55 PM   #30
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Quote:
Originally posted by Magura


No, I use Kapton film


Magura

well - I meant on that ....... but seems that short circuit between headphones of mine was shorter than usual .......



same question ........ ?
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