Hi Have you been through the full alignment process on one or both of the 5370’s ? They are as much an analog beast as they are digital. They *do* drift out of calibration / alignment / adjustment. When they go it’s usually not all of a sudden. They just gradually get worse and worse as the adjustments bake away inside that hot box.
=========== 35 ns pops are pretty big. Are you seeing spikes or are you seeing steps? Spikes can be just about anything, including the next door neighbor’s bug zapper. Steps are a bit more indicative of something actually wrong. In either case, a counter with far less resolution than a 5370 can be used to help “triangulate” the problem. A free running OCXO (or three) is also perfect for this sort of thing. Bob > On Jul 7, 2016, at 10:16 PM, Bob Stewart <[email protected]> wrote: > > 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 > > ----------------------------------------------------------------------------------- > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > 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 > > ----------------------------------------------------------------------------------- > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
