[time-nuts] Re: Water in connectors

[Ole Petter Rønningen]

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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