[time-nuts] Z3805 hold-Over

Doug Parker doug.parker at btinternet.com
Sun Nov 11 14:24:20 EST 2012


Hi John,
 
Thanks for the observation, with the same antenna plugged into my Z3801, I get an SS of at least 90.
 
I'll place a preamp in line to see if that increases the SS on the 3805 , maybe my problem is the GPS RX isn't well. Great point.
 
Of course,  I'll watch out for the 5V power feed going up the coax for the preamp in the antenna.
 
73s
Doug
G4DZU
 

________________________________
 From: jmfranke <jmfranke at cox.net>
To: Doug Parker <doug.parker at btinternet.com>; time-nuts at febo.com 
Sent: Sunday, 11 November 2012, 19:04
Subject: Re: [time-nuts] Z3805 hold-Over
  
Your 21 ns for 1PPS and T1 does not look too bad, but the satellite received signal strengths are too low. You should have at least four or five SS values above 60-80. I always have at least three SS readings above 100. My Holdover runs between 03 and 4 microseconds.

John  WA4WDL

--------------------------------------------------
From: "Doug Parker" <doug.parker at btinternet.com>
Sent: Sunday, November 11, 2012 1:36 PM
To: <time-nuts at febo.com>
Subject: Re: [time-nuts] Z3805 hold-Over

> 
> 
> 
> Hi,
> 
> I've got a Z3805 from one of the Chineese sources and had problems with the HP 11801 oscillator which came with it. Even after a couple of weeks operartion it was moving vast EFC voltages with the 'Holdover Uncertainty Predict' reaching a lowest of 19uS.
> 
> So I tried the HP oscillator from my Z3801 in the Z3805 and the daily EFC change is back to a resonable level, but after 5 days of settling down, the 'Holdeover Uncertainy Predict' has only got down to 10uS.and is holding about that value.
> 
> Could some one please advise what figures they are getting. As there's something sticking in my mind that the whole system should be lower than 6.3uS after 3 days of locked operation. Or have I been dreaming.....
> 
> I have attached a JPG of my GPSCon graph, hope it helps
> 
> thanks & 73s
> Doug
> G4DZU
> http://www.g4dzu.com/



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