[time-nuts] The home time-lab

Bob Stewart bob at evoria.net
Sun Jul 24 19:29:16 EDT 2016

Hi Brooke,
Thanks for that info.  I've got the important bits (PRS and GPSDOs) now hooked up to an APC Smart-UPS 700.  What will happen when it goes to battery power, I don't know.  I've been doing qualification testing on a new batch of GPSDOs, so I haven't had time to do any testing of power fails.  And as luck would have it, we haven't had any stormy weather, so the power line seems to be stable.  Another few hours of testing on this final unit and I'll hook up a scope, put on a pre-production unit, and pull the cord to see what it all looks like.  Hopefully the switching supply wall warts will be happy with whatever they get.
I did get a Sola 1000VA unit, but I haven't hooked it in yet.  I want to run it from 240VAC rather than from 120, so that means I need to pull a 240V line, and it's just too hot to be in the attic here in Texas.

Bob -----------------------------------------------------------------


      From: Brooke Clarke <brooke at pacific.net>
 To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
 Sent: Sunday, July 24, 2016 4:45 PM
 Subject: Re: [time-nuts] The home time-lab
Hi Bob:

The Sola 500 VA transformer is specified to hole up the line voltage for 3 ms.  (but not a half cycle of the line 

I've connected the Sola CVS transformer to the output of the APC RS1500 backup UPS.  (needed to replace the 2 batteries 
in the main unit and probably within a year the 4 batteries in the optional battery pack.

The Sola transformer is connected to the output of the RS1500.  This will clean up any spikes or narrow drop outs on the 
AC line since when the AC line is active the UPS does nothing.
My hope was that the transformer would clean up the modified square wave output of the UPS, but that does not happen.
Video of APC self test showing waveform on scope:https://youtu.be/DLE0mzAt7KY <https://youtu.be/DLE0mzAt7KY>
I think the modified square wave killed my HP 6200 flat bed scanner.  The best scanner I've used and no longer made.

Have Fun,

Brooke Clarke
The lesser of evils is still evil.

-------- Original Message --------
> 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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