[time-nuts] Z3805A cooling requirements?

Tom Van Baak tvb at LeapSecond.com
Wed Dec 12 01:55:34 UTC 2012

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?


----- 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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