[hpsdr] Munin - Heat Spreader under Final Transistors...

[Bob G Mahrenholz]

Hi Pete,

I bought a 4" piece of 1/8" x 1-1/4" copper bar from Speedy Metals LLC
to put under the output transistors to conduct to my heat sink. It works
great! The transistors really run cool to the touch but the heat sink 
gets quite warm. This was their CA 110 copper bar which they sell by
the inch.

I got one of Communication Concepts 12" heat sinks so I wouldn't have to
listen to a fan and it works.

I used RadioShack's 28-1099 Thermal Compound between the transistors and
the copper bar and between the copper bar and the heatsink.

The piece of copper bar was only $4.60 but the freight cost me $17.30!
I don't have Speedy Metals LLC webb address right off hand but their
E-mail is joe_f at speedymetals.com and their phone is 262-784-4140.

73,
Bob, K4QQK
 

-----Original Message-----
>From: n3evl <n3evl at townisp.com>
>Sent: Jul 27, 2012 1:08 PM
>To: HPSDR list <hpsdr at lists.openhpsdr.org>
>Subject: [hpsdr] Munin - Heat Spreader under Final Transistors...
>
>***** High Performance Software Defined Radio Discussion List *****
>
>I'm nearing completion of my Munin amp and recall reading some postings 
>about the possible need for a copper heat spreader between the bottom of 
>the finals and the aluminum heat sink.  My question is - how essential 
>is it to place something here?
>
>I have some sheet copper in my junk box that is ~1mm thick so I could 
>cut a piece to sit under the finals and attach it to the heat sink if it 
>is thought to be necessary.  Maybe this sheet stock is too thin to make 
>much difference.
>
>Any thoughts/ideas appreciated.
>
>73, Pete, N3EVL
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