[time-nuts] The home time-lab

Bob Stewart bob at evoria.net
Thu Jul 7 22:16:24 EDT 2016

There is one variable that I neglected to mention in the first response.  I've been unhappy with the stability of the 10811s in both 5370s.  So, for this test, I'm using the 10MHz output from another one of my units to supply the clock.  In the past 71,000 seconds of the retest, I'm seeing a phase variance of only +60ps to -80ps in timelab with an "averaging window" of 0.


      From: Tim Shoppa <tshoppa at gmail.com>
 To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
 Sent: Thursday, July 7, 2016 8:16 PM
 Subject: Re: [time-nuts] The home time-lab
1/35ns is about 30MHz. Is there anything in your clock chains that is ticking at 30MHz, such that a false count or slipped count induced by inductive disruption, would cause a 35ns phase jump?
Related thread: https://www.febo.com/pipermail/time-nuts/2016-May/098028.html

Tim N3QE
On Thu, Jul 7, 2016 at 8:44 PM, Bob Stewart <bob at evoria.net> wrote:

I hope this isn't too far off topic, as this is having a big impact on my testing.

I decided to run an A/B test on one of my GPSDOs: comparing the phase of the two 10MHz output channels.  In the middle of the night, there was a long series of 35ns pops in the phase data.  Strangely enough, there was nothing in the data collected directly from the unit involved.  The preceding two days we had had a number of switching transients where the lights blinked but nothing shut down.  So, putting one and one together, I suspect that a fair percentage of the strange results I've been getting has been power-grid related.
So, what to do?  I've been looking at UPS devices, and I don't even understand enough to waste my money on a bad one.  The two big questions seem to be "on-line" and "sine wave".  Make that three: can I trust the mfgs claims?  Is there something affordable that could run a pair of 5370s and maybe another 50W worth of DUTs for up to an hour or two and not be prey to power-line transients?  Or would it be more cost effective to somehow monitor the power line for spikes or phase jumps and blow off tests or cut out the offending data?  From time to time we get a thread on power-line nuts.  Should I have been paying more attention?

Bob - AE6RV
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