Tim,
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.
Bob
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GFS GPSDO list:
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From: Tim Shoppa <[email protected]>
To: Bob Stewart <[email protected]>; Discussion of precise time and frequency
measurement <[email protected]>
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 <[email protected]> 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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