[time-nuts] [Bulk] Re: Z3801A holdover

[J. L. Trantham]

Dave,

I noticed the problem after a 'stormy night' with a power outage.  Definitely fewer sats with lower signal strengths than before.  Typically both the Z3816A and the TBolt tracked exactly the same sats.  

At first, I thought it was an antenna or splitter problem.  When I connected the Z3816A directly to the antenna, number of sats and signal strengths were definitely better.  I tried a different splitter but no improvement.  Only swapping the receiver brought it back to normal.

I'll have to chase down a replacement receiver.  Any suggestions for a better receiver or just go back with what I have?

Thanks.

Joe

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Artek Manuals
Sent: Thursday, February 25, 2016 9:52 AM
To: Discussion of precise time and frequency measurement
Subject: [Bulk] Re: [time-nuts] Z3801A holdover

Joe, Joe and Bob

I am still not ready to condemn the receiver until we have more data..

Do you have any history on how many satellites you were tracking in the past, i.e are the number of sats being tracked and the sat strengths typical for your setup or are they noticeably lower now than in the past? Describe the antenna and its installation. While not ideal at just tracking 4 sats the unit will still track and lock with that few, what is more likely to suffer than anything is the holdover performance than the power up GPSDO accuracy

I have a dead on Oncore here on the bench and there are as far as I know no schematics available and even if there were troubleshooting it could be a REAL challenge, certainly there no "adjustments".

If anyone REALLY wants to see one I can post some up close and personal photos of the receiver board ...only helpful  in discouraging thoughts of repairing it as near as I can tell especially since replacement receivers abound from a list member and on Evil-Bay at reasonable prices

Dave
NR1DX



On 2/25/2016 9:15 AM, J. L. Trantham wrote:
> Joe,
>
> I recently had a problem with my Z3816A where it reported an erroneous date, 2035 IIRC.  However, the time was accurate.
>
> It was only tracking 4 sats and the signal strengths were low.  My TBolt was tracking 8 sats with good signal strength.  My antenna feeds a Symmetricom 58536A 4 way splitter and that feeds the receivers.
>
> I 'rebooted' the unit by turning off power, leaving it overnight then turned it on.  Same thing.
>
> I then removed and replaced the 'battery backup batteries' (they tested good) that I had installed and restarted it.  It never found itself.  I then gave it the Lat/Long and it found itself, with the correct time but with only 4 sats and with low signal strength.
>
> I then replaced the GPS receiver and now all is well.  It found itself, 8 sats, good signal strength, correct date and time, as compared to the TBolt.
>
> So, the GPS receiver might be on the list for your problem.
>
> Does anyone know anything about how to repair these receivers?
>
> Thanks.
>
> Joe
> WB4BPP
>
>
>
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of 
> Joseph Gray
> Sent: Wednesday, February 24, 2016 10:37 PM
> To: Discussion of precise time and frequency measurement
> Subject: [Bulk] [time-nuts] Z3801A holdover
>
> I just took a look at my Z3801A that has been in holdover for some time. I have been too busy to do anything about it until now.
>
> Before looking at the receiver stats just now, my first guess was that the Oncore GPS board went bad. However, I see that it is currently tracking 4 sats. I also see that the 1pps is invalid. Does this still point to a failed Oncore board?
>
> Attached is a screenshot showing the receiver stats.
>
> I will open this thing up over the weekend to check voltages and such.
> Until then, any tips on where to look are appreciated.
>
> Joe Gray
> W5JG
>
> _______________________________________________

--
Dave
Manuals at ArtekManuals.com
www.ArtekManuals.com

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