[time-nuts] Fwd: Dusty 53131A

Bob Camp kb8tq at n1k.org
Mon Mar 6 02:19:51 EST 2017


53131’s are dust magnets. It is not at all uncommon for them to fill up with dust, 
overheat, and die. Popping them open every 10 years or so to clean them out is
well worth the effort. 


> On Mar 5, 2017, at 8:54 PM, Scott Stobbe <scott.j.stobbe at gmail.com> wrote:
> Recently the fan in my 53131 has been making a pretty awful sound, so its
> time to replace it. When I disassembled the counter I found the trim cap
> had turned into a fur ball. Not that it really matters since it runs on an
> external reference, but its interesting to see if the dust has any effect.
> See https://www.flickr.com/photos/147407087@N06/32427230764/. So with the
> unit disassembled I logged the effect of removing the dust by logging a
> GPSDO during the cleaning process.
> Must of the dust was around the shroud of the trim cap. Near the mounting
> terminals there was fairly minimal amounts of dust. At least in this
> instance, if the dust had any impact on frequency, its orders of magnitude
> below the thermal instability of the AT crystal.
> The crystal appears to be in a to-39 3-lead package. It is also
> freestanding directly in front of the exhausting cooling fan...
> <Dusty53131A.png>_______________________________________________
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