[hpsdr] Fully enclosed Hermes cooling?

[mstangelo at comcast.net]

John,

You may want to consider using external 5 and 12 volt power supplies if you
to un the Hermes board full time. This will eliminate the heat from the
voltage regulator chips.

Mike N2MS
----- Original Message -----
From: John Marvin <jm-hpsdr at themarvins.org>
To: hpsdr at lists.openhpsdr.org
Sent: Thu, 03 Jan 2013 19:09:48 -0000 (UTC)
Subject: Re: [hpsdr] Fully enclosed Hermes cooling?

***** High Performance Software Defined Radio Discussion List *****

I have the TAPR version of Hermes and have put it into a fully enclosed 
cabinet, so I've been a little concerned about heat also. I decided to 
put the recommended heatsink on the bottom of the board below the 5V 
regulator, but I have my doubts about how helpful that is. It seems it 
would be better (if such a part existed) to put a miniature heatsink 
directly on the regulator. The A/D converter works equally as hard for 1 
receiver as it would for multiple receivers, so I don't see a reason to 
put a heat sink on that.

I've run the 4 receiver version of the firmware with all four receivers 
going for almost 90 hours straight without any issues, although the 
cabinet did get fairly warm (but I wouldn't call it hot).  I've also 
tried a 7 receiver experimental version of the firmware, but the longest 
I've gotten that to work is about 12 hours. That may be due to the 
higher heat, but I think it is more likely due to the common code it 
probably shared with the 1.8 (or earlier) version of the firmware that 
contained the "hang" bug (that has since been fixed). I haven't had a 
chance to try the new 2.1 firmware with all 5 receivers running for an 
extended period.

I don't know if the extra heat will have any significant long term 
effect or cause premature failure, but usually the kind of heat required 
to cause damage in the medium to long term causes flakey behavior in the 
short term.

Looking forward to testing the 13 receiver version of the firmware :). 
Probably not going to happen, but I can always dream!

John
AC0ZG

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