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/

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@btinternet.com> Sent: Sunday, November 11, 2012 1:36 PM To: <time-nuts@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/ > _______________________________________________ > 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.

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@cox.net> To: Doug Parker <doug.parker@btinternet.com>; time-nuts@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@btinternet.com> Sent: Sunday, November 11, 2012 1:36 PM To: <time-nuts@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/ > _______________________________________________ > 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.

Yes, I guess, signal strength is essential. My holdover uncertainty is (after 1 weeks) about 1 to 2us. Volker DF9PL Am 11.11.2012 20:04, schrieb jmfranke: > 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@btinternet.com> > Sent: Sunday, November 11, 2012 1:36 PM > To: <time-nuts@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/ > > > >> _______________________________________________ >> 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. > > > > _______________________________________________ > 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. > >

You can easily check the 5V by measuring at the open antenna plug. When plugging the antenna, total current consumption should increase by about 10mA or so. Am 11.11.2012 20:24, schrieb Doug Parker: > 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@cox.net> > To: Doug Parker<doug.parker@btinternet.com>; time-nuts@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@btinternet.com> > Sent: Sunday, November 11, 2012 1:36 PM > To:<time-nuts@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/ > > > >> _______________________________________________ >> 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. > _______________________________________________ > 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. > >

Hi Most of mine get down to ridiculously low numbers after a few weeks to a few months on. How long seems to depend on how many years the unit has been off power. Any estimate under 500 ns is questionable with that hardware. The firmware seems to be quite happy reporting numbers well below that. Bob On Nov 11, 2012, at 1:36 PM, Doug Parker <doug.parker@btinternet.com> wrote: > > > > 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/<3801-5Days.jpg>_______________________________________________ > 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.

Hi You may well over drive the GPS board if you put more amplification in the line. If the antenna and coax work ok with a 3801, they should be fine with a 3805. If you have a very high gain setup, it may be ok for the 3801 and be over driving the 3805 already. What kind of antenna and coax are you using? Bob On Nov 11, 2012, at 2:24 PM, Doug Parker <doug.parker@btinternet.com> wrote: > 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@cox.net> > To: Doug Parker <doug.parker@btinternet.com>; time-nuts@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@btinternet.com> > Sent: Sunday, November 11, 2012 1:36 PM > To: <time-nuts@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/ > > > >> _______________________________________________ >> 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. > _______________________________________________ > 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.

Doug wrote: >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. Note that most GPS engines (including the one in the 3805) report carrier-to-noise ratio (C/N), NOT signal strength. C/N is a function mostly of the antenna location (and, to a lesser extent, the antenna itself). So, while a preamp will raise the signal strength, it will also raise the noise strength, and the C/N -- which is what matters -- will not change much. The cure is to find a better location for your antenna (and possibly get a better antenna, but location is the main thing). If the only better location you have requires a long cable run, a preamp may help to offset cable attenuation. Best regards, Charles

Hi Bob,   Thanks for the thoughts, Chuck has provided the wisdom to solve my problem. With GPSCon, my readings on the Z3801 are 'Signal Strength' and the Z3805A are 'C/N' which are entirely different. I'd not noticed  the change in designation on the  display.   My antenna is a typical 'Base Station bullet' with an integral 20+dB preamp and 15 feet of RG58   thanks Doug     ________________________________ From: Bob Camp <lists@rtty.us> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Sunday, 11 November 2012, 20:52 Subject: Re: [time-nuts] Z3805 hold-Over Hi You may well over drive the GPS board if you put more amplification in the line. If the antenna and coax work ok with a 3801, they should be fine with a 3805. If you have a very high gain setup, it may be ok for the 3801 and be over driving the 3805 already. What kind of antenna and coax are you using? Bob On Nov 11, 2012, at 2:24 PM, Doug Parker <doug.parker@btinternet.com> wrote: > 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@cox.net> > To: Doug Parker <doug.parker@btinternet.com>; time-nuts@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@btinternet.com> > Sent: Sunday, November 11, 2012 1:36 PM > To: <time-nuts@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/ > > > >> _______________________________________________ >> 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. > _______________________________________________ > 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. _______________________________________________ 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.

Hi If the coax is real RG58 (as in solid poly core) you have 3-4 db of loss in it. If it's foam core, you have even less. The normal antennas have enough gain to easily handle 10 - 15 db of loss. A bigger concern than loss would be shielding. Depending on what's running around (moon bounce transmitters …), something like quad shield RG-6 might do better. Bob On Nov 12, 2012, at 4:28 AM, Doug Parker <doug.parker@btinternet.com> wrote: > Hi Bob, > > Thanks for the thoughts, Chuck has provided the wisdom to solve my problem. With GPSCon, my readings on the Z3801 are 'Signal Strength' and the Z3805A are 'C/N' which are entirely different. I'd not noticed the change in designation on the display. > > My antenna is a typical 'Base Station bullet' with an integral 20+dB preamp and 15 feet of RG58 > > thanks > Doug > > > > > ________________________________ > From: Bob Camp <lists@rtty.us> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > Sent: Sunday, 11 November 2012, 20:52 > Subject: Re: [time-nuts] Z3805 hold-Over > > Hi > > You may well over drive the GPS board if you put more amplification in the line. If the antenna and coax work ok with a 3801, they should be fine with a 3805. If you have a very high gain setup, it may be ok for the 3801 and be over driving the 3805 already. > > What kind of antenna and coax are you using? > > Bob > > On Nov 11, 2012, at 2:24 PM, Doug Parker <doug.parker@btinternet.com> wrote: > >> 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@cox.net> >> To: Doug Parker <doug.parker@btinternet.com>; time-nuts@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@btinternet.com> >> Sent: Sunday, November 11, 2012 1:36 PM >> To: <time-nuts@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/ >> >> >> >>> _______________________________________________ >>> 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. >> _______________________________________________ >> 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. > > > _______________________________________________ > 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. > _______________________________________________ > 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.