[time-nuts] z3801 - holdover and recovery issue

Magnus Danielson magnus at rubidium.dyndns.org
Fri Jul 15 13:54:17 UTC 2011


On 15/07/11 15:06, Ron Hahn (EI2JP) wrote:
> On 7/11/2011 3:57 PM, Charles P. Steinmetz wrote:
>> Ron wrote:
>>
>>> Colleagues,
>>>
>>> My Z3801 has developed a peculiar problem over the last few weeks.
>>>
>>> The problem is that it seems to oscillate between "gps-lock" and
>>> "holdover". When I checked further it seems to be oscillating
>>> between, locked, recovery, and holdover, mostly staying in recovery
>>> and holdover.
>>
>> Have you tried substituting another antenna and cable (even just a
>> short cable with the antenna indoors)? This looks like what I'd expect
>> a 3801 to do if its antenna or antenna connection were intermittent.
>> While you have it disconnected, check that the 3801 is putting antenna
>> power on the coax.
>>
> Hi Charles,
>
> I disconnected the mushroom-style antenna and measured the voltage
> between the TNC centre pin and shield; This was 5 volts. Connection
> looked clean and unaffected by weather or moisture ingress. Reattached
> the connector and screwed it on until it was tight, then rechecked
> gpscon. Satellites are now being received.
>
> So I can only deduce from this that the TNC male (cable end) to TNC
> female (mushroom antenna) is intermittent. Don't understand why but it
> now looks like it is receiving 6 satellites and the 3801 is in
> "recovery" mode.
>
> http://www.ei2jp.org/gpscon/gpsstat.htm

Somehow I am not surpriced, as similar problems have been showing up at 
my place. Fixing some cable and connector problems removed the issues.

Hope it stays stable now and you get good lockup.

Cheers,
Magnus



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