[time-nuts] Rack-mounting an LPRO? (Heatpipe cooler)

paul swed paulswedb at gmail.com
Sun Feb 28 17:50:36 UTC 2010


An approach is to put just the rb unit in say the basement.
Its always cooler (at least mine is)
The area I work in can get pretty warm in the summer if I am gone for a week
This approach solves that problem pretty well

On Sun, Feb 28, 2010 at 11:25 AM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> A few words of caution here.
>
> I have run compact rubidiums for a number of years. It is *very* tempting
> to skimp on the heat sink. Cooling something that's heating it's self up
> sounds silly.
>
> Having tried the "not much heat sink" approach several times (I'm a slow
> learner). The rubidium does die fairly soon. Properly cooled they last for a
> long time. You need to get the baseplate below 40 C. Getting it below 30 C
> might be better, but that's impractical in most settings.
>
> The units dump around 10 watts of heat. The number will vary depending on
> the supply voltage, the exact baseplate temperature, and the exact model. If
> your normal room temperature is 20 C, 10 watts and a rise to 40 gives you 2
> C/W.
>
> In a tightly packed rack, in the summer, at high supply voltage, the heat
> sink required  can easily get to < 1 C/W. My answer to that is to move the
> rubidium out of the rack or simply turn it off when things get that warm.
>
> Fans are a good way to improve the efficiency of any heat sink. The problem
> here is that rubidiums are sensitive to magnetic field. Having a device with
> a magnetic motor in it right next to one probably is a bad idea. If you put
> in fans, put them in the back of the case, and keep them away from the
> rubidium.
>
> Bob
>
>
> On Feb 28, 2010, at 10:55 AM, Joe Gwinn wrote:
>
> > At 2:02 AM +0000 2/28/10, time-nuts-request at febo.com wrote:
> >> Date: Sat, 27 Feb 2010 20:02:05 -0600
> >> From: Ed Palmer <ed_palmer at sasktel.net>
> >> Subject: Re: [time-nuts] Rack-mounting an LPRO?
> >> To: Discussion of precise time and frequency measurement
> >>      <time-nuts at febo.com>
> >> Message-ID: <4B89CE9D.4060103 at sasktel.net>
> >> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
> >>
> >> Sorry, the pictures got lost.  Let's try again.
> >>
> >> Ed Palmer wrote:
> >>> What else is going to be in the rack?  If your 1U enclosure is packed
> >>> in tight between other devices there might be no cooling at all.  You
> >>> might need a fan to move some air.
> >>>
> >>> I don't know if you can find something like this, but I scavenged heat
> >>> sinks from an old Compaq DL760 server that might fit your situation.
>  Here's what the heat sink looks like.  The aluminum plate is about
> >>> 1/4" (6.4 mm) thick.  Notice the heat pipes.
> >>>
> >>>
> >>>
> >>> Here's what it looks like on the LPRO.  You'll have to drill holes in
> >>> the plate to match the LPRO.
> >>>
> >>>
> >>>
> >>> It's not perfect, but it certainly does the job - particularly if you
> >>> had a fan blowing through the fins.  The total height is about 1.75"
> >>> (45 mm).
> >>>
> >>> But remember, the more you cool the LPRO, the more power it will draw
> >>> to keep itself warm so you don't want to overdo the cooling.
> >>>
> >> > Ed
> >>>
> >> [snip]
> >> -------------- next part --------------
> >> A non-text attachment was scrubbed...
> >> Name: 1.jpg
> >> Type: image/jpeg
> >> Size: 37469 bytes
> >> Desc: not available
> >> URL: <
> http://www.febo.com/pipermail/time-nuts/attachments/20100227/9f21a5a8/attachment.jpg
> >
> >> -------------- next part --------------
> >> A non-text attachment was scrubbed...
> >> Name: 2.jpg
> >> Type: image/jpeg
> >> Size: 33025 bytes
> >> Desc: not available
> >> URL: <
> http://www.febo.com/pipermail/time-nuts/attachments/20100227/9f21a5a8/attachment-0001.jpg
> >
> >
> > The aluminum fin and copper pipe assembly integrated with the heatsink
> plate is most likely a heat pipe of some kind, as that's what Thermacore
> makes.  It's a model 2644, from the nameplate, but no joy at the
> Thermacore.com website.
> >
> > Joe Gwinn
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


More information about the time-nuts mailing list