Re: [time-nuts] Z3801A holdover

[Artek Manuals]

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 behavestill 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 <manu...@artekmanuals.com> 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:time-nuts-boun...@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
manu...@artekmanuals.com
www.ArtekManuals.com




--
Dave
manu...@artekmanuals.com
www.ArtekManuals.com

---
This email has been checked for viruses by Avast antivirus software.
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_

Re: [time-nuts] Z3801A holdover

[Joseph Gray]

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 <manu...@artekmanuals.com> 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:time-nuts-boun...@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
> manu...@artekmanuals.com
> www.ArtekManuals.com
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
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Re: [time-nuts] Z3801A holdover

[Artek Manuals]

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-boun...@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
manu...@artekmanuals.com
www.ArtekManuals.com

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Re: [time-nuts] Z3801A holdover

[Artek Manuals]

Joe

It would have been helpful to see the graph BEFORE you power-cycled if 
you still have that data stream


I would not jump to any conclusions at this point until the power supply 
voltages have been checked . Downloading the schematics from KO4BB.com 
of the power supply and oven control circuits will give you some insight 
. There are numerous test points on the power supply board which make 
reading the various voltages a snap.



The 1 PPS being invalid I believe points to the fact that the DO is out 
of whack not the receiver.


I see your unit now has 28,000 hours on it so it is no longer a spring 
chicken for sure

Dave




On 2/25/2016 9:09 AM, Joseph Gray wrote:

Dave,

Thanks for the tips. I also got a message off list telling me about
the EFC issue and that I missed this discussion recently on the list.

Last night, I power cycled the Z3801A. It has been running all night.
Attached is the graph you requested. If I read this correctly, yes, it
looks like the unit has maxed out the EFC voltage one way.

Joe Gray
W5JG


On Thu, Feb 25, 2016 at 1:54 AM, Artek Manuals  wrote:

>On 2/24/2016 11:37 PM, Joseph Gray wrote:

>>
>>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
manu...@artekmanuals.com
www.ArtekManuals.com

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Re: [time-nuts] Z3801A holdover

[J. L. Trantham]

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-boun...@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

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Re: [time-nuts] Z3801A holdover

[Joseph Gray]

Dave,

Thanks for the tips. I also got a message off list telling me about
the EFC issue and that I missed this discussion recently on the list.

Last night, I power cycled the Z3801A. It has been running all night.
Attached is the graph you requested. If I read this correctly, yes, it
looks like the unit has maxed out the EFC voltage one way.

Joe Gray
W5JG


On Thu, Feb 25, 2016 at 1:54 AM, Artek Manuals  wrote:
> On 2/24/2016 11:37 PM, Joseph Gray wrote:
>>
>> 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
>
>
>
> Joe
>
> I'm no expert since I've only just begun playing with my Z3801A for the last
> 6 weeks after having it in mothballs for 15 years but having just gone
> through a Oncore failure on the surface it seems unlikely I would wish for
> slightly better signal strengths but I dont know what you experienced in the
> past.
>
> I am led to believe that EFC errors are typically associated with the
> Oscillator unit itself rather than the Oncore receiver,My first guess after
> that is the 10811 oscillator has "aged" out of a correctable range. In Z38xx
> program open the the graph window and send us a screen shot of that window,
> this should give us and idea of what the actual EFC value and behavior was
> just before things died.
>
> My next instinct ( but wait for a few other more experienced comments come
> out) is to turn the unit off and let it cool down for a day then do a cold
> start :SYSTEM:PRESET followed by a GPS:POS;SURV:ONCE command and see if it
> re-initializes. Takes about 2 hours typically since you have known good
> position  data.
>
> There is a description of the power supply and oven control circuitry for
> the oven on KO4BB.com .search for Z3801A in the MANUALS section You are
> basically looking to see if +/- 15VDC and +5VVDC lines are correct
>
> Dave
> NR1DX
>
>
> --
> Dave
> manu...@artekmanuals.com
> www.ArtekManuals.com
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
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Re: [time-nuts] Z3801A holdover

[Bob Camp]

Hi

The TRAIM error will happen with a small number of sats and a location 
estimate that is less than perfect. I would not go to crazy about that part.

First question — why so few sats? You really need to have full screen of 
locked sats. That can be a feed line / antenna issue. The old Oncore boards
are pretty deaf. A setup that works fine with other stuff … maybe not so much
with one of them.

Second question — did the unit get moved from somewhere else and still
thinks it is in the other location? If so it would struggle just like the 
screen shows.

I’d get those two out of the way first.

Bob

> On Feb 24, 2016, at 11:37 PM, Joseph Gray  wrote:
> 
> 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
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Re: [time-nuts] Z3801A holdover

[Artek Manuals]

On 2/24/2016 11:37 PM, Joseph Gray wrote:

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



Joe

I'm no expert since I've only just begun playing with my Z3801A for the 
last 6 weeks after having it in mothballs for 15 years but having just 
gone through a Oncore failure on the surface it seems unlikely I would 
wish for slightly better signal strengths but I dont know what you 
experienced in the past.


I am led to believe that EFC errors are typically associated with the 
Oscillator unit itself rather than the Oncore receiver,My first guess 
after that is the 10811 oscillator has "aged" out of a correctable 
range. In Z38xx program open the the graph window and send us a screen 
shot of that window, this should give us and idea of what the actual EFC 
value and behavior was just before things died.


My next instinct ( but wait for a few other more experienced comments 
come out) is to turn the unit off and let it cool down for a day then do 
a cold start :SYSTEM:PRESET followed by a GPS:POS;SURV:ONCE command and 
see if it re-initializes. Takes about 2 hours typically since you have 
known good position  data.


There is a description of the power supply and oven control circuitry 
for the oven on KO4BB.com .search for Z3801A in the MANUALS section You 
are basically looking to see if +/- 15VDC and +5VVDC lines are correct


Dave
NR1DX


--
Dave
manu...@artekmanuals.com
www.ArtekManuals.com

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[time-nuts] Z3801A holdover

[Joseph Gray]

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
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