[time-nuts] Z3805A cooling requirements?

paul swed paulswedb at gmail.com
Wed Dec 12 02:22:08 UTC 2012


Yes they do assume this. Or at least a standard relay rack. Most of these
units should have come out of mobile telcom sites. The air in these
facilities is reasonable but often not all that great. They do get hot. But
the relay racks are 2 posters nothing else surrounding the racked equipment
so there is the ability to radiate heat.
What started the thread I think was the gear was in a closed 4 post rack.
That would tend to be an oven or allow hot spots to develop.
Further we get gear thats X years old. In my experience the switching
supplies are towards the end of their life. Really just the filter caps.
But as mentioned they are epoxy blocks so you can't easily change the caps
out.
Suspect thats an easy way to fry these supplies. Age + heat = death. :-)
My 3801 lost one of its supplies ages ago. I adapted another newer one in
that I had. Hey what are you going to do.
Regards
Paul
WB8TSL

On Tue, Dec 11, 2012 at 8:55 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> The telecom closets and data centers I've visited have a significant
> amount of airflow. Could it be that there is an assumption that these
> telecom-rack GPSDO expect some level of air?
>
> /tvb
>
> ----- Original Message -----
> From: <SAIDJACK at aol.com>
> To: <time-nuts at febo.com>
> Sent: Tuesday, December 11, 2012 5:20 PM
> Subject: Re: [time-nuts] Z3805A cooling requirements?
>
>
> > Stu,
> >
> > a fan is about the worst thing you can do for your Z3805 it will
> > significantly worsen the stability of the output frequency. The oven
> inside does  get
> > warm, that's why it is an oven :)
> >
> > The power consumption will go down once it heats itself up, the unit is
> > designed to work without a fan sitting on a desk etc. Just make sure the
> vent
> > holes are not clogged.
> >
> > Sounds like your Z3816 had a failure that caused the units power  supply
> to
> > overheat.
> >
> > bye,
> > Said
> >
> >
> > In a message dated 12/11/2012 16:22:10 Pacific Standard Time,
> > stewart.cobb at gmail.com writes:
> >
> > This may  be a newbie question, but I'm a newbie, so:
> >
> > Do the HP telecom GPSDOs  (Z38xx) require external airflow for cooling?
> > They don't have built-in  fans, but they sorta look like they depend on a
> > rack-level cooling fan,  which a telecom rack would almost certainly
> have.
> >
> > I ask because I  bought a Z3816 awhile back which worked for about a week
> > and then failed. I  traced the failure to an internal power supply brick,
> > which had a big  finned heat-sink attached but nevertheless smelled
> > overheated and was  shorted internally.
> >
> > I never found a replacement power brick, and I  don't have time to mess
> with
> > it right now, so I recently bought a Z3805A.  It, too, looks like it's
> > working, but it started to feel awfully warm after  a few hours, so I
> > unplugged it for now.
> >
> > It probably wouldn't take  much of a fan to bring the internal
> temperature
> > down close to ambient, and  the fan could be powered easily enough from
> the
> > supply rails. But that  might create a temperature gradient where the
> > designers didn't intend one.  Or it might cause problems I don't even
> know
> > about yet.
> >
> > At the  moment, the Z3805A is in a fan-less 19-inch rack with a bunch of
> > other  equipment, in a lab environment. Should it have its own  fan?
> >
> > Cheers!
> > --Stu
> >
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