<html><head><style data-externalstyle="true"><!--
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph {
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
}
p.MsoListParagraphCxSpFirst, li.MsoListParagraphCxSpFirst, div.MsoListParagraphCxSpFirst, p.MsoListParagraphCxSpMiddle, li.MsoListParagraphCxSpMiddle, div.MsoListParagraphCxSpMiddle, p.MsoListParagraphCxSpLast, li.MsoListParagraphCxSpLast, div.MsoListParagraphCxSpLast {
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
line-height:115%;
}
--></style></head><body><div data-externalstyle="false" dir="ltr" style="font-family:Calibri,'Segoe UI',Meiryo,'Microsoft YaHei UI','Microsoft JhengHei UI','Malgun Gothic','Khmer UI','Nirmala UI',Tunga,'Lao UI',Ebrima,sans-serif;font-size:12pt;"><div><div>Hi Mike,</div><div> </div><div>Are you sure that the edge of the copper spreader is straight?</div><div> </div><div>Roderick Wall, vk3yc.</div></div><div data-signatureblock="true"> </div><div style="padding-top: 5px; border-top-color: rgb(229, 229, 229); border-top-width: 1px; border-top-style: solid;"><div><font face="Calibri, 'Segoe UI', Meiryo, 'Microsoft YaHei UI', 'Microsoft JhengHei UI', 'Malgun Gothic', 'Khmer UI', 'Nirmala UI', Tunga, 'Lao UI', Ebrima, sans-serif" style='line-height: 15pt; letter-spacing: 0.02em; font-family: Calibri, "Segoe UI", Meiryo, "Microsoft YaHei UI", "Microsoft JhengHei UI", "Malgun Gothic", "Khmer UI", "Nirmala UI", Tunga, "Lao UI", Ebrima, sans-serif; font-size: 11pt;'><b>From:</b> AA8K73 GMail<br><b>Sent:</b> Thursday, October 10, 2013 1:36 PM<br><b>To:</b> HPSDR</font></div></div><div> </div>***** High Performance Software Defined Radio Discussion List *****<br><br><br>Has anyone else noticed a concave surface in the heat sink in <br>the latest Munin kit?<br><br>When I hold the copper spreader against the heat sink, it <br>touches on the ends, but the middle portion is about 1 mm away. <br> I could:<br><br><br>1. File the copper spreader and/or aluminum heat sink to get a <br>closer fit.<br><br>2. Put the copper spreader in my arbor press and bend it to <br>conform to the heat sink. But then it wouldn't be flat for the <br>transistors.<br><br>3. Fill the gap with something to provide a better heat transfer <br>than air.<br><br>4. Not worry and just screw it together.<br><br><br>What do you think?<br><br><br>Also, what about using Penetrox (zinc particles in petroleum) in <br>place of ordinary heat sink compound (ceramic particles in <br>silicon, I think) for the spreader/sink interface? I've used <br>Penetrox frequently in industrial electrical work when joining <br>aluminum with copper.<br><br><br>Mike - AA8K<br>_______________________________________________<br>HPSDR Discussion List<br>To post msg: hpsdr@openhpsdr.org<br>Subscription help: http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org<br>HPSDR web page: http://openhpsdr.org<br>Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/<br></div></body></html>