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Old 3rd March 2009, 07:03 PM   #31
JimT is offline JimT  Canada
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Which jfet is that?

Jim
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Old 3rd March 2009, 07:04 PM   #32
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On F3's I use just grease and anodizing for the JFET.

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Old 3rd March 2009, 07:27 PM   #33
Magura is offline Magura  Denmark
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Quote:
Originally posted by JimT
Which jfet is that?

Jim

A LU1014-Magura


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Old 3rd March 2009, 07:30 PM   #34
Magura is offline Magura  Denmark
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Quote:
Originally posted by Zen Mod



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



same question ........ ?

Phase change material, RS stocks it, Bergquist makes it. Nice to work with, works very well.


Magura

DISCLAIMER: I gave an answer to what I believe the question is.
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Old 3rd March 2009, 07:34 PM   #35
Magura is offline Magura  Denmark
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Quote:
Originally posted by flg

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???

I can't remember how thick the Kapton film I have is, I bought it long ago.


Yeah, I see you get the picture of where I'm heading

Kapton will though not be an option, as the thermal cycling will be a deal breaker.

Magura
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Old 4th March 2009, 02:53 AM   #36
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Hey Magura, What about Mica between the primary copper heat spreader and the main heatsink? I may be wrong, but I seem to remember that mica is a better heat conductor and better electrical insulator than most of the synthetic insulator materials. Only thing that is an issue is that it's hard to get nice flat, planar pieces of mica.


Peace,

Dave

P.S. you could also go synthetic diamond, but that might move the cost up just a bit.
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Old 22nd March 2009, 10:50 PM   #37
udailey is offline udailey  United States
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So what type of screw/bolt are you using? Nylon?
Uriah
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Old 22nd March 2009, 11:09 PM   #38
Magura is offline Magura  Denmark
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Quote:
Originally posted by udailey
So what type of screw/bolt are you using? Nylon?
Uriah

Plain steel bolts. Isolation is sorted out by a shoulder washer.


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Old 23rd March 2009, 12:38 AM   #39
udailey is offline udailey  United States
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Right on. Thanks for the reply.
Uriah
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Old 24th March 2009, 11:01 PM   #40
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Quote:
Thickness?
McMaster has .002 thick "thermally conductive" Kapton. Has anyone tried this? I was considering getting a sheet for my next amp (if the design is ever published.....).

They have other thicknesses available in the "electrically conductive" variety, but I'm guessing this is not what you want.

JJ
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