Joe
Getting the antenna outside for a decent signal even if not in the clear
would be advisable before you spend money on other possible solutions
...Certainly explains the only tracking 4 problem
As a minimum I would go portable on a card table in the yard or parking
lot for several hours to see if that explains things...
The splitter is by definition not a loss-less device either... going
direct to the Z3801 with the antenna is a worthy exercise as well to see
how things behave....still the unusual EFC plot has me wondering
ultimately if the 10811 or the power supply are being funky.
Try a better antenna location with no splitter first before you open the
box and start flailing at the power supply and receiver.
Dave
NR1dx
On 2/25/2016 4:52 PM, Joseph Gray wrote:
Dave,
I haven't monitored the Z3801A in quite some time, but I do remember
that it used to track more satellites. For probably a year, the unit
would go into holdover often. Then a few months ago, it stayed in
holdover. Last night was the first time that I have looked at the
stats and information recently.
The antenna is a Symmetricom timing antenna. It used to sit on top of
my service monitor, but has recently been raised up several feet, in
the clear. I can't easily get it outside because I'm renting
(single-story frame house). When the Z3801A used to track more sats,
the antenna was in the old location.
I am using a 4-port Symmetricom GPS splitter. My Lucent 2-box GPSDO is
on one of the ports. I moved the Z3801A to another port, to make sure
that wasn't the problem.
What I will do tonight when I get home is to see how many sats the
Lucent is tracking.
Joe Gray
W5JG
On Thu, Feb 25, 2016 at 8:52 AM, Artek Manuals <[email protected]> wrote:
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:[email protected]] 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
[email protected]
www.ArtekManuals.com
--
Dave
[email protected]
www.ArtekManuals.com
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