Re: [time-nuts] Z3801A OCXO manual trimming

Someone mentioned the right non-lazy approach with a summing/offset opamp. Do agree. But then just for a try use a V supply and a 10K. I seem to recall tracing the DAC to an opamp. The EFC line is pretty easily accessed. Its one of the little coax cables. The other even lower risk approach is

[time-nuts] Z3801A OCXO manual trimming

Success! I disassembled the oven and adjusted the OCXO frequency up about 5 Hz. Lady Heather reported the DAC changed from +99.99% with no lock to -90% with lock to GPS. Hopefully I did not increase the frequency too much. The long term aging/drift direction has been down - which caused the

Re: [time-nuts] Z3801A OCXO manual trimming

Hi Assuming you can break the EFC lead to the OCXO, you aren’t going to damage anything inside by feeding the EFC line with +/- 5V. If you are going to tear open the OCXO, the line will need to be pulled anyway. Without knowing what they drive the EFC line with, it’s hard to know if the

Re: [time-nuts] Z3801A OCXO manual trimming

Hi The control range should be +/- 5V if I remember correctly. If it’s not, the only other standard would be 0-5V. There is zero logic in running a wider swing mod to an OCXO at a lower EFC range. It indeed sounds like the DAC has trouble. Bob > On Mar 6, 2018, at 1:24 AM, Mark Sims

Re: [time-nuts] Z3801A OCXO manual trimming

Crazy thought.Could you just force a DC offset into the EFC assuming the internal varicap is not out of range. It would be simply adding a resistor to pull up or down to see if you can get a bit of pull and allow the dac to move back in range a bit. Its a band aid. I know its sort of crazy.

[time-nuts] Z3801A OCXO manual trimming

I'm not sure what the Z3801A uses for EFC range. Heather uses the EFC relative command to report the EFC setting. That command reports values from -100% to 100%. There is a command that reports the DAC input in counts, but nothing documented that shows volts/count. Since the DAC is at -2V

Re: [time-nuts] Z3801A OCXO manual trimming

/installing antennas including one of my GPS antennas. From: Mark Sims <hol...@hotmail.com> To: "time-nuts@febo.com" <time-nuts@febo.com> Sent: Monday, March 5, 2018 7:36 PM Subject: [time-nuts] Z3801A OCXO manual trimming Or, it you are sure it's the OCXO,  go

[time-nuts] Z3801A OCXO manual trimming

Or, it you are sure it's the OCXO, go shopping for a new one.There is a reputable seller with them (the double oven version) for $100 on Ebay. A couple of things to try... monitor the EFC voltage, power up the unit, and see if it is changing as it attempts to lock. If it does not, you

Re: [time-nuts] Z3801A OCXO manual trimming

The easiest solution would be to drill a hole in the right place in order to access the screw that covers the trimmer hole of the inner OCXO housing. Does anyone have a disassembled double oven 10811 at hands and could take the required measures plus check if any vital parts of the outer oven are

Re: [time-nuts] Z3801A OCXO manual trimming

Hi Either tear into the OCXO or go shopping for a new(er) GPSDO. The Z38xx devices all had a lot more in common with each other than they did differences. The OCXO design changed from the 10811 to various more modern designs. The disciplining process seems to have remained pretty much the same

Re: [time-nuts] Z3801A OCXO manual trimming

Crazy thought.Could you just force a DC offset into the EFC assuming the internal varicap is not out of range. It would be simply adding a resistor to pull up or down to see if you can get a bit of pull and allow the dac to move back in range a bit. Its a band aid. I know its sort of crazy. But

Re: [time-nuts] Z3801A OCXO manual trimming

Thank you, Hal, for these links and to others for your comments. Setting the oven temperature on a turning point appears tedious. Perhaps there is enough range in the frequency adjustment to put the oscillator back on frequency - or close enough for the EFC to be effective. If not, I may have

Re: [time-nuts] Z3801A OCXO manual trimming

I dug in deep and there is an adjustment. Thats the great news. The bad news was never able to put the oven back together. It was a mess. The insulation stuff deteriorated. (Might mean over heated oven) The various wires going to the oscillator are wrapped about 4 times around the oven. I am sure

[time-nuts] Z3801A OCXO manual trimming

Oops... I checked and the Z38xx devices don't have a DAC setting command. It was the UCCM GPSDOs that have a SCPI command for controlling the DAC manually, - > When I press "D" Lady Heather replies: Manual disciplining not supported by this receiverpress ESC

Re: [time-nuts] Z3801A OCXO manual trimming

n...@npgcable.com said: > Does the oscillator have an adjustment? If so, is this somewhat accessible > without destroying the assembly? Are there pictures of the oscillator > assembly? https://www.realhamradio.com/GPS-oven-journey.htm https://www.realhamradio.com/z3801a-turning-point.htm

Re: [time-nuts] Z3801A OCXO manual trimming

Hi > On Mar 4, 2018, at 10:30 PM, Joe Hobart wrote: > > > Mark, > > When I press "D" Lady Heather replies: > > Manual disciplining not supported by this receiverpress ESC > > > Questions about the Z3801A: > > Does the oscillator have an adjustment? If so, is this

Re: [time-nuts] Z3801A OCXO manual trimming

Mark, When I press "D" Lady Heather replies: Manual disciplining not supported by this receiverpress ESC Questions about the Z3801A: Does the oscillator have an adjustment? If so, is this somewhat accessible without destroying the assembly? Are there pictures of the oscillator

[time-nuts] Z3801A OCXO manual trimming

Lady Heather has a command that lets you set the DAC voltage. It's in the "D" menu. Depending upon the firmware, you may need to disable disciplining first (also in the "D" menu). If the DAC command works to change the OCXO freq, the osc EFC and DAC are probably OK. If it does not, I'd

Re: [time-nuts] Z3801A OCXO manual trimming

Hi > On Mar 4, 2018, at 1:13 PM, Joe Hobart wrote: > > My Z3801A failed about a year ago (there was a warning the electronic > frequency > control was nearing a limit). > > Symptoms (most from GPS Control and Lady Heather: > > Frequency about 1E-8 low > > Time Invalid

Re: [time-nuts] Z3801A OCXO manual trimming

My Z3801A failed about a year ago (there was a warning the electronic frequency control was nearing a limit). Symptoms (most from GPS Control and Lady Heather: Frequency about 1E-8 low Time Invalid (many hours off) Date 6 months old DAC 99.9969 percent Life 72K Hours Lady

Re: [time-nuts] Z3801A OCXO manual trimming

t; On Behalf Of Bob kb8tq > Sent: Saturday, March 03, 2018 2:07 PM > To: Tom Curlee <tcur...@sbcglobal.net>; Discussion of precise time and > frequency measurement <time-nuts@febo.com> > Subject: Re: [time-nuts] Z3801A OCXO manual trimming > > Hi > > First off

Re: [time-nuts] Z3801A OCXO manual trimming

> Interesting point about the heater not working vs. the XTAL having drifted > too far. Any logs you made of EFC percent over the past few months or years will help verify the off-the-rail theory. Another thing to try -- turn-off the Z3801A for a couple of hours to let it cool. Disconnect the

Re: [time-nuts] Z3801A OCXO manual trimming

.net>; Discussion of precise time and > frequency measurement <time-nuts@febo.com> > Subject: Re: [time-nuts] Z3801A OCXO manual trimming > > Hi > > First off some basics about OCXO’s. > > In a single oven design, you have a heater th

Re: [time-nuts] Z3801A OCXO manual trimming

d frequency measurement <time-nuts@febo.com> Subject: Re: [time-nuts] Z3801A OCXO manual trimming Hi First off some basics about OCXO’s. In a single oven design, you have a heater that warms up the entire crystal and the guts of the oscillator. It is on all the time and it gets things u

Re: [time-nuts] Z3801A OCXO manual trimming

On 2018-03-03 3:56 PM, Tom Curlee wrote: What I don't understand is the purpose of what looks like another coil or heater wrapped around the Kapton printed circuit heater stuck to the inner case. This second coil/heater is 2 layers of 1/8" thick red foam wrapped completely around the inner

Re: [time-nuts] Z3801A OCXO manual trimming

Hi First off some basics about OCXO’s. In a single oven design, you have a heater that warms up the entire crystal and the guts of the oscillator. It is on all the time and it gets things up to a temperature that makes sense for a given crystal. It can be adjusted based on manufacturing data

[time-nuts] Z3801A OCXO manual trimming

Since the Z3801A is being discussed, I thought I'd ask about an issue I'm having with my unit.  I use my Z3801 as my working lab standard for the usual pieces of RF test equipment.  In the past year or so I've had the unit drop out of lock and go into standby mode.  Resetting/cycling power

Re: [time-nuts] Z3801A and Z38XX Issues

cott McGrath <scmcgr...@gmail.com> Sent: Saturday, September 16, 2017 3:48:06 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Z3801A and Z38XX Issues Connect to a terminal emulator and IDQ it you will either see garbage in which case serial config is wrong a

Re: [time-nuts] Z3801A and Z38XX Issues

connection isn't working right. >>> >>> On 9/16/2017 at 12:26 AM, "Richard Solomon" wrote:Not according to >>> the manual, but then that could be my problem !! >>> 73, Dick, W1KSZ >>> Sent from Outlook >>> ___

Re: [time-nuts] Z3801A and Z38XX Issues

:17 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Z3801A and Z38XX Issues Shouldn't that be 8 data bits? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard Solomon Sent: Saturday, September 09, 2017

Re: [time-nuts] Z3801A and Z38XX Issues

gt; 73, Dick, W1KSZ >> Sent from Outlook >> >> From: time-nuts on behalf of Bill Hawkins >> Sent: Sunday, September 10, 2017 8:16:17 PM >> To: 'Discussion of precise time and frequency measurement' >> Subject: Re: [time-nuts] Z3801

Re: [time-nuts] Z3801A and Z38XX Issues

er 10, 2017 8:16:17 PM > To: 'Discussion of precise time and frequency measurement' > Subject: Re: [time-nuts] Z3801A and Z38XX Issues > > Shouldn't that be 8 data bits? > > Bill Hawkins > > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@febo.com

Re: [time-nuts] Z3801A and Z38XX Issues

' Subject: Re: [time-nuts] Z3801A and Z38XX Issues Shouldn't that be 8 data bits? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard Solomon Sent: Saturday, September 09, 2017 4:24 PM I downloaded and installed Z38XX, configured

Re: [time-nuts] Z3801A and Z38XX Issues

ok<http://aka.ms/weboutlook> > > From: time-nuts <time-nuts-boun...@febo.com> on behalf of Bill Hawkins < > bill.i...@pobox.com> > Sent: Sunday, September 10, 2017 8:16:17 PM > To: 'Discussion of precise time and frequency measurement' > Subject:

Re: [time-nuts] Z3801A and Z38XX Issues

r 10, 2017 8:16:17 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Z3801A and Z38XX Issues Shouldn't that be 8 data bits? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard Solomon Sent: Saturday,

Re: [time-nuts] Z3801A

I  didn't look but I think that is up on KO4BB's site. Dave manu...@artekmanuals.com On 9/11/2017 5:31 PM, Magnus Danielson wrote: Hi Dave, This is what I was looking for but could not locate. Thanks! This is what I like with this community, we help each other out! Cheers, Magnus On

Re: [time-nuts] Z3801A

Hi Dave, This is what I was looking for but could not locate. Thanks! This is what I like with this community, we help each other out! Cheers, Magnus On 09/11/2017 07:49 PM, Artek Manuals wrote: Magnus This is available for free download somewhere...not our scan .. reverse engineered

Re: [time-nuts] Z3801A and Z38XX Issues

I seem to remember its 19200, 7,O,1. Regards Paul WB8TSL On Sun, Sep 10, 2017 at 11:01 PM, Mark Sims wrote: > And remember that commands sent to the Z3801A end in Line Feed, not > Carriage Return. > ___ > time-nuts mailing list --

[time-nuts] Z3801A

Fellow time-nuts, Does anyone has the schematic of the PSU-board in the Z3801A? Me and a fellow ham need it. Cheers & 73, Magnus SA0MAD ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

[time-nuts] Z3801A and Z38XX Issues

And remember that commands sent to the Z3801A end in Line Feed, not Carriage Return. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

Re: [time-nuts] Z3801A and Z38XX Issues

Shouldn't that be 8 data bits? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard Solomon Sent: Saturday, September 09, 2017 4:24 PM I downloaded and installed Z38XX, configured both the Port and Device to the recommended parameters:

Re: [time-nuts] Z3801A and Z38XX Issues

Hi Standard generic drill: 1) Swap RX and TX (or check with a voltmeter) 2) Cycle through the normal set of baud rates 3) Double check the jumpers on the 422 to 232 conversion 4) Check with a terminal program, typing in the *IDN? query by hand Yes it’s sort of a mix and match of what’s above.

[time-nuts] Z3801A and Z38XX Issues

I have a working Z3801A, it has had an AC Supply added to it and the RS422 port has been reconfigured to RS232. I downloaded and installed Z38XX, configured both the Port and Device to the recommended parameters: Data Rate: 19,200 Parity: Odd Data Bits: 7 All I can get, looking at the

[time-nuts] Z3801A sending invalid date

My Z3801A just started sending an invalid date in the "T2" format time code message (which is its default format). It says the date is 2017/01/00 and Lady Heather rejects the data and the clock stops updating. My receiver went into rollover last August and I manually set the date which cured

[time-nuts] Z3801A / Z3812A leapsecond funkiness

This morning I checked Z3812A that I had not power cycled and it is now reporting the pending leap second properly. Looks like it takes over 48 hours for these units to recover from the bogus leapsecond condition. ___ time-nuts mailing list --

[time-nuts] Z3801A / Z3812A leapsecond funkiness

As discussed earlier there is a bug in the firmware of these devices where they report the wrong date of a leapsecond if it is announced more than three months in advance. Mine were reporting leapseconds will occur on 30 Sep 2016. Well, the event passed and the devices reset their

Re: [time-nuts] Z3801A gps week rollover

.@febo.com] On Behalf Of Hal Murray Sent: Thursday, September 08, 2016 2:54 PM To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Cc: hmur...@megapathdsl.net Subject: Re: [time-nuts] Z3801A gps week rollover petervince1...@gmail.com said: > Can I just ask why the Z3801

[time-nuts] Z3801A gps week rollover

You might want to try some lithium AA cells. They start out around 1.65V. They are MUCH less prone to leakage than any "alkaleak" battery and have a very long shelf-life (i.e. good for low drain memory backups). As always, when adding a backup battery to a GPS, verify that the battery

Re: [time-nuts] Z3801A gps week rollover

The gps rcvr does not have a batter but will indeed support an external battery. I attached 2 AA batteries in a external easily replaceable holder and ran the 2 wires to the receiver 10 pin plug. (At least I think it was 10) I change the batteries every 2 years not so much for voltage as concern

Re: [time-nuts] Z3801A gps week rollover

kb...@n1k.org said: > The bigger problem for NTP is when the leap second correction process is > thrown off by the “time warp”. When leap seconds get fixed in mid-August > rather than the end of June … not a good thing. Is that still a problem? If so, do you have any details. I don't

Re: [time-nuts] Z3801A gps week rollover

On 09/09/2016 01:17 PM, Bob Camp wrote: Hi On Sep 9, 2016, at 3:06 AM, Magnus Danielson wrote: Hi, On 09/08/2016 11:53 PM, Hal Murray wrote: petervince1...@gmail.com said: Can I just ask why the Z3801As are having week roll-over problems now - I didn't

Re: [time-nuts] Z3801A gps week rollover

Hi > On Sep 9, 2016, at 3:06 AM, Magnus Danielson > wrote: > > Hi, > > On 09/08/2016 11:53 PM, Hal Murray wrote: >> >> petervince1...@gmail.com said: >>> Can I just ask why the Z3801As are having week roll-over problems now - I >>> didn't think it was 2048 weeks

Re: [time-nuts] Z3801A gps week rollover

Hi, On 09/08/2016 11:53 PM, Hal Murray wrote: petervince1...@gmail.com said: Can I just ask why the Z3801As are having week roll-over problems now - I didn't think it was 2048 weeks since GPS "zero-hour" until late on the 6th of April 2019? It's probably 1024 weeks since a date was built

[time-nuts] Z3801A gps week rollover

The Z3801A status page takes 3 seconds to process/send. Not surprising that the time is a bit off. Lady Heather only requests the SYST:STAT message once per minute (at hh:mm:33 seconds) because it blocks the unit from doing anything else while it is handling it. The main things extracted

Re: [time-nuts] Z3801A gps week rollover

hol...@hotmail.com said: > Happy until the next power glitch... the setting does not seem to persist > between boots. There may also be other conditions that causes it to forget > your date. I just power cycled mine. It came back correct without setting the date. I've assumed there is a

Re: [time-nuts] Z3801A gps week rollover

That makes sense - thanks guys! Peter On 8 September 2016 at 22:53, Hal Murray wrote: > > petervince1...@gmail.com said: > > Can I just ask why the Z3801As are having week roll-over problems now - > I > > didn't think it was 2048 weeks since GPS "zero-hour"

Re: [time-nuts] Z3801A gps week rollover

petervince1...@gmail.com said: > Can I just ask why the Z3801As are having week roll-over problems now - I > didn't think it was 2048 weeks since GPS "zero-hour" until late on the 6th > of April 2019? It's probably 1024 weeks since a date was built into the firmware. It's like the year 2000

Re: [time-nuts] Z3801A gps week rollover

Hi After the first batch of GPS devices rolled over, the manufacturers came up with a “fix” for the problem. If the date came out to a number *before* the firmware was issued, it was corrected forward in time. This only works over a single span of GPS dates. Depending on when the firmware

Re: [time-nuts] Z3801A gps week rollover

Can I just ask why the Z3801As are having week roll-over problems now - I didn't think it was 2048 weeks since GPS "zero-hour" until late on the 6th of April 2019? Peter ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

[time-nuts] Z3801A gps week rollover

Yes, rollovers should not be a problem and should only affect the date display. However, I have seen devices/software that use GPS fail to work because of what appears to be an invalid date. It seems that they are validating the data from the receiver and if, for instance, the date is

Re: [time-nuts] Z3801A gps week rollover

they have no effect on 1PPS or 10 MHz outputs. > > /tvb > > - Original Message - > From: "paul swed" <paulsw...@gmail.com> > To: "Discussion of precise time and frequency measurement" < > time-nuts@febo.com> > Sent: Thursday, Septembe

Re: [time-nuts] Z3801A gps week rollover

2016 8:16 AM Subject: Re: [time-nuts] Z3801A gps week rollover > Mark, > From some earlier threads on rollovers. Do you even need to set the time at > all? > Granted not great if the 3801 is a time source, but if its just frequency > do you care? > Thanks > Paul > WB8

Re: [time-nuts] Z3801A gps week rollover

Mark, >From some earlier threads on rollovers. Do you even need to set the time at all? Granted not great if the 3801 is a time source, but if its just frequency do you care? Thanks Paul WB8TSL On Tue, Sep 6, 2016 at 11:30 AM, Mark Sims wrote: > Happy until the next power

[time-nuts] Z3801A gps week rollover

Happy until the next power glitch... the setting does not seem to persist between boots. There may also be other conditions that causes it to forget your date. And when setting the date, you should disconnect the antenna first, then power on. Once the unit starts tracking satellites you

Re: [time-nuts] Z3801A gps week rollover

I had one that screwed up. I power cycled and set the date. It's happy now. I'm not sure of the exact recipe to tell it the right date. After feeding it a date of roughly today, the status screen jumped to Jan 2007. After it found a few satellites and such, it jumped to Sep 2016. --

Re: [time-nuts] Z3801A gps week rollover

That would be sunday midnight, GPS time, as GPS time-gears have GPS week shift between saturday and sunday. This naturally makes Monday extra monday as the system that fail do it during sunday. Cheers, Magnus On 09/05/2016 06:29 AM, Mark Sims wrote: I did a little math on the dates and it

Re: [time-nuts] Z3801A gps week rollover

hol...@hotmail.com said: > I did a little math on the dates and it looks like the rollover happened in > the last couple of days... Thanks for the heads up. Mine started on Aug 17th /var/log/ntp/clockstats.20160817:57617 2.033 127.127.26.1 T21997010102300103 8 64 0 That's from ntpd's

Re: [time-nuts] Z3801A gps week rollover

Hi The rollover is in the GPS module firmware. If you dig into it, they didn't quite update the firmware once every 3 months, but almost that often. Each manufacturer latched onto various versions as they sailed by. None of them had a validation process that could keep up with 4 releases a

Re: [time-nuts] Z3801A gps week rollover

On 9/4/2016 10:48 PM, Mark Sims wrote: Sometime (I didn't have it connected) in the last couple of weeks my Z3801A went into gps week rollover. If you have a Z3801A that had been working properly you might want to check yours. Different firmware versions roll over at different times. My

[time-nuts] Z3801A gps week rollover

I did a little math on the dates and it looks like the rollover happened in the last couple of days... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the

[time-nuts] Z3801A gps week rollover

Sometime (I didn't have it connected) in the last couple of weeks my Z3801A went into gps week rollover. It now reports the year as 1997. It had been working propely. Lady Heather caught the anomaly and automatically added 1024 weeks worth of seconds to the date/time which compensated for

Re: [time-nuts] Z3801A recovering

, 2016 2:14 PM To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Subject: Re: [time-nuts] Z3801A recovering Art, Thanks for the link. Very useful information. I also read the 'VP Service note" posted there. Is that note also referring to the oscillator, or

Re: [time-nuts] Z3801A recovering

After about three hours: https://dl.dropboxusercontent.com/u/19599147/Z3801A%203hr.png Ignore the graph discontinuity at the beginning. I had to power cycle to change to UTC. Joe Gray W5JG On Sun, May 1, 2016 at 1:30 AM, Joseph Gray wrote: > In past discussions about

Re: [time-nuts] Z3801A recovering

In past discussions about replacing a 6-channel Oncore in a Z3801A with an 8-channel VP Oncore, some claimed that the VP had to first be put into 6-channel mode, others indicated this was not necessary. Earlier tonight, I put a VP (still in 8-channel mode) into my malfunctioning Z3801A. Monitoring

Re: [time-nuts] Z3801A recovering

Art, Thanks for the link. Very useful information. I also read the 'VP Service note" posted there. Is that note also referring to the oscillator, or some other component that needs periodic recalibration. In any case, it seems that they are recommending that we power down our GPSDO units every

Re: [time-nuts] Z3801A recovering

frequency measurement <time-nuts@febo.com> Subject: Re: [time-nuts] Z3801A recovering Now that I finally have some replacement Oncore VP modules, I've been able to do some tests and comparisons. Using WinOncore 12, I tested the VP's that I got from Pete. Then I compared the old module

Re: [time-nuts] Z3801A recovering

Now that I finally have some replacement Oncore VP modules, I've been able to do some tests and comparisons. Using WinOncore 12, I tested the VP's that I got from Pete. Then I compared the old module from the Z3801A. The old module seems to be deaf. It reports that it sees plenty of satellites,

Re: [time-nuts] Z3801A recovering

Joe I am confused by the fact that it shows the unit has been in HOLDOVER for 496 hours if you did a fresh survey Did you do a SYSTEM:PRESET: and GPS:POS:SURVEY:ONCE commands to initiate the new survey or just the survey command or What software are you running? I would power the

[time-nuts] Z3801A EEPROM

Referring to this old post: https://www.febo.com/pipermail/time-nuts/2011-December/061718.html In particular, this statement: "but If the RTC in the receiver is not set or its battery has failed, and the reference year stored in EEPROM is also wrong, the receiver may select the wrong 20-year

Re: [time-nuts] Z3801A recovering

Hi If you look at the scale on the EFC plot, it’s likely showing you a 1 LSB change on the dac…. Bob > On Mar 16, 2016, at 7:38 PM, Joseph Gray wrote: > > As I mentioned a while back, my trusty Z3801A, which has worked well > for several years, went into holdover some time

Re: [time-nuts] Z3801A recovering

Dave, I power cycled it about 20 days ago, which did no good. That is the 496 hours holdover time. This time, I did just the survey once command. I'll try your suggestion before attacking the hardware. I'm currently using Z38xx.exe. Joe Gray W5JG On Thu, Mar 17, 2016 at 4:30 AM, Artek Manuals

[time-nuts] Z3801A recovering

As I mentioned a while back, my trusty Z3801A, which has worked well for several years, went into holdover some time ago and stayed there. Until recently, I haven't had time to look into this. About 20 days ago, I did power cycle it to see if that made a difference. It did not. In the middle of

Re: [time-nuts] Z3801A recovering

The saga continues. Last night, I hooked up the second Z3801A that I got recently. At first, it was having a hard time finding satellites and then locking. I did a PRESET and started a new survey late last night. All day and this evening, it has been operating flawlessly. Tonight, I did a quick

Re: [time-nuts] Z3801A EEPROM

Magnus, Yes, I know that is how it works. I was just curious if anyone knew how and where that information was stored in the EEPROM. I thought it might be nice not to fool around with trying to set the date before it queried the satellites, to avoid the 1024 week issue. If I could update the

Re: [time-nuts] Z3801A EEPROM

jg...@zianet.com said: > I know, this issue doesn't come up often, unless the unit get's power > cycled, which isn't often (usually years). A long time ago, I had to set the date on a Z3801A. It's been power cycled several times since then without troubles. So either setting the date is good

Re: [time-nuts] Z3801A EEPROM

Joe, On 03/18/2016 02:33 AM, Joseph Gray wrote: Referring to this old post: https://www.febo.com/pipermail/time-nuts/2011-December/061718.html In particular, this statement: "but If the RTC in the receiver is not set or its battery has failed, and the reference year stored in EEPROM is also

Re: [time-nuts] Z3801A recovering

Joe, I'd be interested in knowing what you find out. My Z3801 is acting a lot like yours. It is currently locked, but. On Thu, Mar 17, 2016 at 8:15 AM, Joseph Gray wrote: > Dave, > > I power cycled it about 20 days ago, which did no good. That is the > 496 hours holdover time.

Re: [time-nuts] Z3801A holdover

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 ha

Re: [time-nuts] Z3801A holdover

roblem. >> >> 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 J

Re: [time-nuts] Z3801A holdover

anks. 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 Z3801

Re: [time-nuts] Z3801A holdover

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

Re: [time-nuts] Z3801A holdover

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

Re: [time-nuts] Z3801A holdover

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

Re: [time-nuts] Z3801A holdover

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

Re: [time-nuts] Z3801A holdover

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

[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

[time-nuts] Z3801A GPSDO discipline algorithm

Does anyone have knowledge of or better yet access to the algorithm or flow diagram of the GPSDO control process for the Z38xx family .. No real reason..just normal engineer curiosity but I would like to know what the unit takes into account, 1PPS error (or does it average x number of

[time-nuts] Z3801A Internal A/C Supply ??

OK if you followed the previous thread on this unit you will remember that the front half of my supply the reverse polarity and under/ over voltage switch is bad but the DC-DC converter half of the supply is good. I initially cut a trace and rerouted the power input to bypass the voltage

Re: [time-nuts] Z3801A Internal A/C Supply ??

Dave wrote: Should I be concerned about. 1) Noise from the supply or the A/C lines now inside the box Yes, you should always be concerned about both radiated and conducted noise generated by switching supplies, inside or outside the enclosure. Personally, I would never run the output

Re: [time-nuts] Z3801A and FE-5680A Allen Variances

I briefly considered designing a board that would GPS discipline the FE-5680A. It’d simply substitute an RS-232 level shifter for the DAC and would speak the protocol to trim the frequency. I haven’t done it, though, because the OH300’s performance specification at low tau is not that far

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