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vdi_nenna 9th July 2011 01:42 AM

F3 Heatsink
Hello Everyone,

I want to build a F3 (aka Zen 9) and have a set of 4 heatsinks that might work, but not sure if they big enough. I think they are cutting it close. F3 dissipates 100w per channel. That's a tall order. Intended to use 1 heatsink for the 2 mosfets and another for the power jfet and mosfet. Here's the dimensions of one heatsink.

Back plate: 10-3/4" x 4-9/16' x 1/4'

Fins: 18 per HS 1-3/8 x 4-5/8 x 3/32, Not including height of back plate

Overall Dimensions: 10-3/4 x 4-9/16 x 1-5/8

Let me know what you think! :)



vdi_nenna 9th July 2011 02:03 AM

2 Attachment(s)
Couple of pics.

Bksabath 9th July 2011 02:59 AM

As you already have the sink why not rig up the mosfets as if you where matching the VGS run them at the suply voltagge and bias to suit
EG 25 V 2 A = 50 Watt an see how hot they get
It is difficoult to say from pictures
Base plate only 8 mm? fins 40? + they would run cooler if anodised black.

digits 9th July 2011 04:52 AM

My estimate with 100W through that is 50C above ambient....

Nelson Pass 9th July 2011 07:32 PM

2 per ch, they should be fine.


vdi_nenna 11th July 2011 02:20 AM

I was going to build the F3 with heat sinks only on the bench; without a case. This way, if these are not big enough, I'll just fine other HS to use.

Funny thing happened a couple of weeks ago. Had a home energy audit. Auditor had FLIR with him. The F5 and Mini A amps were warming up when they got there.
Both amps read 103 - 110 degrees F. Good to know. :)

Thanks for the help,


Lazybutt 12th July 2011 01:26 PM

haha reminds me I bought an IR "ear" Thermometer for my daughter... out of curiosity I pointed it to my DACs shunt regs heatsinks.. the thing seems to work quite accurately since it showed ~65C and I just (barely) cannot put my hand for 3 secs. (After that I probed all sorts of things in the house to check and I was amazed at the range of temps it measured

Nice IR Temp probe for 15$ !

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