[time-nuts] Re: Water in connectors

[Ole Petter Rønningen]

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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