[time-nuts] Re: PRS-10 heatsink design

[Dana Whitlow]

I mount my PRS-10 vertically (so that the channels between the fins are
vertical),
with the connector on top.  This orientation was chosen simply for best
access to
the connector, but yields heat sink temperatures down around 45C to 50C.
 The
unit is open and fully exposed to the air.  I run it at 24Vdc.

The open mounting is obviously best for natural convective cooling, but does
leave the stability somewhat vulnerable to ambient temperature variations,
drafts, etc, although I've not had obvious problems with this.

If you want to combine good cooling with low dependence on rapid variations
in ambient temperature, I suspect the best way is to interpose a very thick
aluminum (or copper) block between the heatsink flange of the PRS-10 and
the heatsink.  The block will add minimal thermal resistance, but will
serve as
a thermal lowpass filter.  The downside to this is that full warmup of the
PRS-10
will take longer.

Dana


On Wed, Jun 23, 2021 at 2:05 AM James Wilson <jmw at fastmail.com> wrote:

> My limited experience with the factory heatsink for the PRS-10 has left me
> pretty unsatisfied. It seems ok for brief bench evaluation but not for
> permanent enclosure installation. Reported unit temps are in the 70 - 75 °C
> range with it sitting on a bench in a 25 °C room. It needs to be turned on
> its side or upside down for any convection to take heat away, or for fans
> to be directed at the fins. There are no side or top screw holes on the
> PRS-10 so you can’t mount it in that orientation. Has anyone found or built
> a better heatsink that can use active cooling?
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