[time-nuts] Re: Water in connectors

[Dana Whitlow]

Ah, yes.  The wonderful thing about our modern science (and the toys that
arise from it)
is that there is a bottomless treasure trove of interesting things to
investigate.

It occurred to me that one could expand a bit on Bob's point to include the
probable
variation of water's dielectric constant when it goes between liquid and
solid states.

I once had a big problem with a 2m repeater's transmission line wherein a
connector
near the bottom end "filled" with water.  I think the amount was little
more than a ml,
but its effect was to bring the repeater to its knees.  I unscrewed the
connector,
drained a few drops from it, dried it with a hanky, and all was back to
normal upon
reassembly.  This should not be too surprising considering water's
dielectric constant
of around 80.

Good luck with your own investigations.

Dana


On Sat, Mar 27, 2021 at 11:53 AM Ole Petter Rønningen <opronningen at gmail.com>
wrote:

> Oh, no qustion that it would be interesting, but I’d hate to «tie up» the
> gear for a month on a low cost patch antenna, when I have a much better one
> temorarily taken down - basically I just wanted a quick check of how much
> worse things are on «low end gear» - somewhat predictably that only served
> to uncover more questions than it answered..
>
> > 27. mar. 2021 kl. 17:39 skrev Dana Whitlow <k8yumdoober at gmail.com>:
> >
> > My own belief is that almost everything can be blamed on GPS, but then
> much
> > if not
> > most is my own fault for using an indoor antenna only about 6 or 7 feet
> > above ground
> > level.
> >
> > Except when excessive lightning activity is around, I run a
> > continuous setup comparing
> > 10 MHz phase between a T'Bolt GPSDO and a Rb, showing I & Q waveforms on
> a
> > very
> > slow roll-mode 'scope display which shows the most recent 4 hours.  It
> just
> > sits there
> > and runs, and I glance at it many times per day in passing.  It gets very
> > messy much
> > of the time.
> >
> > A month-long recording could net you quite a bit of couch time  :-)
> >
> > Dana
> >
> >
> >> On Sat, Mar 27, 2021 at 11:21 AM Ole Petter Rønningen <
> opronningen at gmail.com>
> >> wrote:
> >>
> >> Active HM, yes - nothing in the logs that corresponds, except a .5 degC
> >> diurnal temperature change - which roughly coincides with the outdoor
> temp,
> >> so no help there..
> >>
> >> This was meant as a quick-and-dirty check, so a months is not in the
> cards
> >> - but that second antenna/receiver is climbing on my list of
> priorities, in
> >> imminent danger of surpassing «doing nothing on the couch»! :)
> >>
> >>>> 27. mar. 2021 kl. 16:52 skrev Dana Whitlow <k8yumdoober at gmail.com>:
> >>>
> >>> Ole,
> >>>
> >>> If you can stand the suspense, a time error recording of a month or
> more
> >>> duration
> >>> would probably be pretty informative (and interesting for us to see).
> >>>
> >>> And when you speak of the maser, is that an active hydrogen maser?  If
> >> so,
> >>> you're
> >>> a lucky man (unless it's in the process of dying).  But there should be
> >>> scads of
> >>> diagnostics being logged, which should be enough to enable making a
> >> fairly
> >>> good
> >>> confidence check on it.
> >>>
> >>> Dana
> >>>
> >>>
> >>>> On Sat, Mar 27, 2021 at 8:33 AM Ole Petter Rønningen <
> >> opronningen at gmail.com>
> >>>> wrote:
> >>>>
> >>>> Hi, Dana
> >>>>
> >>>> Thats the peculiar thing - these last 48 hors theres been a pretty
> clear
> >>>> 24 hour cycle, pointing to temperature as the culprit; but the
> >> preceeding
> >>>> 48 hours the phase shift did not follow a 24 hour period at all; the
> >>>> wheather has been all over the place, so it is hard to say.. More data
> >>>> needed! As always..
> >>>>
> >>>> (of course, there is always a possibility that I’ve somehow bungled
> the
> >>>> data, and the period has been 24 hours all along)
> >>>>
> >>>> This is why I am looking for ballpark figures for the two main
> suspects;
> >>>> water and temperature.
> >>>>
> >>>> I guess I should bite the bullet and rig up a second receiver/antenna
> >> so I
> >>>> can take the maser out of the equation.. (and reseal the connectors
> >>>> properly)
> >>>>
> >>>>
> >>>>>> 27. mar. 2021 kl. 14:04 skrev Dana Whitlow <k8yumdoober at gmail.com>:
> >>>>>
> >>>>> Ole,
> >>>>>
> >>>>> You did not mention whether this timing anomaly is periodic or
> steadily
> >>>>> growing.
> >>>>> That information could be of considerable diagnostic significance.
> >>>>>
> >>>>> Dana
> >>>>>
> >>>>>
> >>>>>> On Sat, Mar 27, 2021 at 6:08 AM Ole Petter Ronningen <
> >>>> opronningen at gmail.com>
> >>>>>> wrote:
> >>>>>>
> >>>>>> Hi, All
> >>>>>>
> >>>>>> I am trying to chase down a 2-3-4 ns/day "anomaly" in a gpsdo I am
> >>>> working
> >>>>>> on - it could be temperature sensitivity in the antenna (cheap patch
> >>>>>> jobbie), or I suspect my sealing of the outside connectors may not
> be
> >>>>>> watertight. I just wanted to ask the list of anyone know of/has an
> >>>> estimate
> >>>>>> of how much the propagation delay on an N and/or SMA can reasonably
> be
> >>>>>> expected to change in the presence of water? is 3 ns in the right
> >>>> ballpark,
> >>>>>> or would that effect be way bigger/smaller?
> >>>>>>
> >>>>>> Likewise, does anyone have reasonably accurate figures for how much
> >>>>>> temperature could be expected to affect the delay of signals? 20 ps?
> >> 20
> >>>> ns?
> >>>>>> Looking for some rough figures so I can look in the right
> direction..
> >>>>>>
> >>>>>> I've used the same gpsdo, cable and location with a high quality
> >> antenna
> >>>>>> without seeing these effects, so I am fairly certain it is the
> antenna
> >>>> (or
> >>>>>> my reference maser giving up the ghost..)
> >>>>>>
> >>>>>> Thanks!
> >>>>>> Ole
> >>>>>> _______________________________________________
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