[time-nuts] 5070B once more....

John Miles jmiles at pop.net
Wed May 20 10:01:41 UTC 2009


> Has anybody tried to replace these
> fans with a
> more modern type (12/24 volt). I'm sure the designers were being very
> proper, but I cannot believe that a counter should require such a large
> volume of air moving through it ?
> I have an EIP 545 Counter and
> an HP 5335A
> which both have Papst fans and are very noisy
> Any ideas on this.
> Roy

The 5370 counters are unusually power-hungry, at about 160 watts for my
5370B.  The airflow through the instrument is where the noise is coming
from, not so much the fan itself (try powering the fan up outside the
counter, holding it in your hand, and it'll be much quieter).  Can't speak
for EIP but I don't think it's a good idea to alter the factory airflow
specs on HP gear, in most cases.

>Now I'm wondering which software I could use to grab data from it to the PC
>and then to analyze the buffers to see the stability of my rubidium
>source synchronised with the 1pps coming from the GPS.

I'm not sure it's possible to make continuous stability measurements (Allan
deviation, etc.) directly with a 5370 since they don't support
running/overlapped measurements between readings.  If you can work with a
1-pps output and can provide a divider for your reference, it can be done
with a picket-fence technique (e.g.
http://horology.jpl.nasa.gov/papers/picket_uffc.pdf ) which I haven't tried
yet.

If anyone thinks it might be worthwhile, I could throw together a GPIB app
to implement Greenhall's paper for the 5370B with a Prologix or NI board...
but my guess is that most people have been using other gear for that sort of
thing.

-- john, KE5FX




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