F5 Heat sinks

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flg

flg

Member
Joined 2005
O.K. In the interest of accuracy and all, I'm thinking I can paralell 2 IR IRFP240s (we'll I can't find any 9240s). I'll use a kerotherm pad on each with no Goo, Grease or other thermal conductive substance. I'll use a 1 ohm Source resistor on both and a typical current source "regulator" transistor drivin by 1 of the source resistors to control them. Just like N.P. I'll make it adjustable because I want to test for more than 1.3A through 2 devices, depending on what happens of coarse.
First I'll set it up for 1.3A through each transistor and about 23V and watch the temp on my 8" section of 10.08" Heat Sink USA H.S.. I'll monitor an accurate power on the devices and try to chart the results in a usuable range.
If we are lucky, I'll slide this thing into work with me and put it in my wind tunnel under the IR camera for you. I can't promise much because it's a little more difficult than it sounds. IR emissivity with my camera and raw metal surface don't get along to well. The easiest way to deal with this is to paint the H.S. with something that has typical emissivity. Or, maybe just paint the spots I'm measuring? I'll think some more about it. Time for bed...
 
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crazycody1993

Member
Joined 2011
tinitus said:
well, they dont rot ;)

but I sure hope its not "pirate copy stuff" you have on order :headbash:
Click to expand...

That's very true!
And after finding this site, I don't know if it is a pirated piece or not, I'm guessing so, which I want to apologize for ahead of time. I'll post a link in the morning to where I got it from and you guys can Bea the judge, I was emailed the schematic, and it is exactly the F5 design picture. Which doesn't seem promising. And obviously I'll be able to tell more when I can hold the board in my hand and look at it, I think looking through the photo gallery I saw someone with the same PCB, I'll be able to tell more in the morning though
 
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crazycody1993

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Joined 2011
labjr said:
You should read the F5 manual. It says a 6X8 piece of heatsink with 2" fins per output device. That's 96 sq in per channel. Any less will probably risk running too hot. A 5 x 17 shape doesn't seem to be optimal for the F5 since the outputs would have to be too far apart to cool.
Click to expand...

what if you were to use a flat piece of flat bar stock, to mount the output devices on, and run it further out on the heat sinks of the 5x17? kinda working on the principal of a thicker base plate, but to a more specific area?
 
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terryaaa

Member
Joined 2010
Hummm ? Got awfully quiet in here.
That must have been right off the crazy scale CrazyCody.

I'd be worried about coupling. that joint needs to be a good one to efficiently transfer the heat. If your going to try that you might consider a copper plate. much like large CPU heatsinks.
Copper is twice as effective at conducting heat across that area and would spread the heat evenly if you got it the right length.

That's just thinking to far outside the box (Rack mount pun intended)
 
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