[time-nuts] Bodnar "Precision Frequency Reference (GPS Clock)" AND LeoNTP Networked Time NTP Server Questions

Mark Goldberg marklgoldberg at gmail.com
Fri May 18 02:54:19 EDT 2018


On Thu, May 17, 2018 at 7:19 PM, Clay Autery <cautery at montac.com> wrote:

> Anyone who is using one (or both) of these, and/or folks who have a
> logical opinion:
> -  Not sure how much I plan to have the unit connected via USB. Beyond
> curiosity data gathering for a while, I'm thinking at some point I want it
> to be disco'd and forgotten.  One less potential USB cable radiating or
> needing ferrites.
>

I have the Bodnar Mini which only has a USB connection. You can connect it
to a USB power only source. I have found a large variation (20 dB) in close
in phase noise, depending on how clean the power source is. I am using a
power only wall wart with an added series ferrite core / shunt cap to get
acceptable results ( -103 dBc/Hz at 10 Hz offset). I don't know if there is
more internal filtering on the separate power input of the 2 output
version. So far peak ADEV at Tau = 20s is about 2e-10. It would be nice to
improve that.

You can also get widely varying spurs, phase noise and ADEV depending on
the register values chosen to provide a specific output frequency. Many
different sets of register values may be used to provide the same output
frequency. I have not determined a pattern. I just calculated different
values and tried them out.

Regards,

Mark
W7MLG



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