[hpsdr] Munin heat sink and spreader

[Tim ORourke]

You would have to spend a lot of energy with a file to remove 1mm from copper with a file!
Old tool maker here Tim W4YN


-----Original Message-----
>From: AA8K73 GMail <aa8k73 at gmail.com>
>Sent: Oct 10, 2013 6:14 AM
>To: HPSDR <hpsdr at openhpsdr.org>
>Subject: Re: [hpsdr] Munin heat sink and spreader
>
>***** High Performance Software Defined Radio Discussion List *****
>
>
>Thanks gentlemen.
>
>I was thinking of the metal particles providing the thermal 
>conductivity (Wiedemann–Franz law), but I suspect that the per 
>cent of contact area is small.
>
>When I held the spreader and sink together to check for fit, I 
>noticed the gap and turned the spreader over to see if it was 
>bowed.  I used a metal straight edge against the spreader and 
>the spreader was flat.  Looking at the reflections in the 
>spreader, I couldn't find any optical distortion.  I am 
>impressed with the quality of that spreader.
>
>Longitudinally, the heat sink is very straight.  It just curves 
>transversely.  Thanks for the confirmation Berndt.
>
>I used to maintain copper resistance-welding fixtures 
>(ignitrons; too long a duration and they would open the 400 amp 
>line fuses), and used lathe, mill, surface grinder, and shaper.
>
>I'm concerned about someone else removing too much material in 
>search of flatness.  Too deep and it would require a shim to 
>match the transistor to board height requirement; and make two 
>more thermal interfaces.  Buying another drilled and tapped heat 
>sink would be costly.
>
>I hope to carefully file the sink and take < 1 mm away.
>
>
>73,
>Mike - AA8K
>
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Tim O'Rourke 
W4YN at ARRL.Net
Low Power Amateur Radio Rocks 
Member of Flying Pigs,ARCI,GQRP,RSGB,ARRL Life Member
NHRA Life Member

 1381400814.0