[time-nuts] The home time-lab

[Bob Camp]

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 <bob at evoria.net> 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 <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
>  -----------------------------------------------------------------------------------
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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