[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi, Yeah, I've seen the Lucent timing pair setup, and shipping cost was for sure involved into breaking it up into the modules and a cable. Always nice to see how it all looked. Cheers, Magnus On 2021-10-15 14:45, Bob kb8tq wrote: Hi There are ( or used to be ) pictures of the full up cell stations that stuff like the 3801 and it’s cousins went into. Just how much searching it would take to find them … who knows. My recollection of them is a very boring bunch of faceplates in a couple of side by side custom racks. Couple LED's here / connectors there, not a lot else. Back in the era when LPro’s were $30, the outfit that was selling the Lucent timing module with them in it would happily sell you the entire setup, shelter and all. Bob On Oct 15, 2021, at 6:00 AM, Magnus Danielson via time-nuts wrote: Hi, Well, designs from before SA off did get better performance, even if not optimum for the new condition. As they where installed, it did in itself not cue for a shift, but rather, as the equipment it was installed with was tossed, these receivers could be salvaged and used on their own. It would be neat to see how that installation actually looked, because it's pulled from some chassi and I've never seen how that setup really looked and was wired. Other receivers where not integrated the same way, so they would have longer operational life. Cheers, Magnus On 2021-10-15 02:35, Bob kb8tq wrote: Hi The stability profile of the GPS timing signal changed significantly when SA was turned off. Things like sawtooth correction that didn’t make much difference in the 1990’s now did make a difference. Time constants and OCXO parameters that made sense “before” didn’t make sense “after”. More or less: When you make profound changes in the GPS timing signal, the best approach to accurately recovering that signal has to change to match the new signal. Does everybody change everything the next day? Of course not. It takes a while for folks to work out what’s what with the “new rules”. Bob On Oct 14, 2021, at 8:12 PM, Hal Murray wrote: kb...@n1k.org said: The other way to look at it: The Z3801 and it???s kin basically went obsolete in 2000 when SA was turned off. Once that happened, the design approach changed. Could you please say more. What changed in the design approach? Can I tell the difference by looking at a box? Or poking at the serial port? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi There are ( or used to be ) pictures of the full up cell stations that stuff like the 3801 and it’s cousins went into. Just how much searching it would take to find them … who knows. My recollection of them is a very boring bunch of faceplates in a couple of side by side custom racks. Couple LED's here / connectors there, not a lot else. Back in the era when LPro’s were $30, the outfit that was selling the Lucent timing module with them in it would happily sell you the entire setup, shelter and all. Bob > On Oct 15, 2021, at 6:00 AM, Magnus Danielson via time-nuts > wrote: > > Hi, > > Well, designs from before SA off did get better performance, even if not > optimum for the new condition. As they where installed, it did in itself not > cue for a shift, but rather, as the equipment it was installed with was > tossed, these receivers could be salvaged and used on their own. It would be > neat to see how that installation actually looked, because it's pulled from > some chassi and I've never seen how that setup really looked and was wired. > > Other receivers where not integrated the same way, so they would have longer > operational life. > > Cheers, > Magnus > > On 2021-10-15 02:35, Bob kb8tq wrote: >> Hi >> >> The stability profile of the GPS timing signal changed significantly when SA >> was turned off. >> Things like sawtooth correction that didn’t make much difference in the >> 1990’s now did >> make a difference. Time constants and OCXO parameters that made sense >> “before” didn’t >> make sense “after”. >> >> More or less: When you make profound changes in the GPS timing signal, the >> best approach >> to accurately recovering that signal has to change to match the new signal. >> Does everybody >> change everything the next day? Of course not. It takes a while for folks to >> work out what’s >> what with the “new rules”. >> >> Bob >> >>> On Oct 14, 2021, at 8:12 PM, Hal Murray >>> wrote: >>> >>> >>> kb...@n1k.org said: The other way to look at it: The Z3801 and it???s kin basically went obsolete in 2000 when SA was turned off. Once that happened, the design approach changed. >>> Could you please say more. What changed in the design approach? >>> >>> Can I tell the difference by looking at a box? Or poking at the serial >>> port? >>> >>> >>> >>> -- >>> These are my opinions. I hate spam. >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >>> an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >> email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi, Well, designs from before SA off did get better performance, even if not optimum for the new condition. As they where installed, it did in itself not cue for a shift, but rather, as the equipment it was installed with was tossed, these receivers could be salvaged and used on their own. It would be neat to see how that installation actually looked, because it's pulled from some chassi and I've never seen how that setup really looked and was wired. Other receivers where not integrated the same way, so they would have longer operational life. Cheers, Magnus On 2021-10-15 02:35, Bob kb8tq wrote: Hi The stability profile of the GPS timing signal changed significantly when SA was turned off. Things like sawtooth correction that didn’t make much difference in the 1990’s now did make a difference. Time constants and OCXO parameters that made sense “before” didn’t make sense “after”. More or less: When you make profound changes in the GPS timing signal, the best approach to accurately recovering that signal has to change to match the new signal. Does everybody change everything the next day? Of course not. It takes a while for folks to work out what’s what with the “new rules”. Bob On Oct 14, 2021, at 8:12 PM, Hal Murray wrote: kb...@n1k.org said: The other way to look at it: The Z3801 and it???s kin basically went obsolete in 2000 when SA was turned off. Once that happened, the design approach changed. Could you please say more. What changed in the design approach? Can I tell the difference by looking at a box? Or poking at the serial port? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi The stability profile of the GPS timing signal changed significantly when SA was turned off. Things like sawtooth correction that didn’t make much difference in the 1990’s now did make a difference. Time constants and OCXO parameters that made sense “before” didn’t make sense “after”. More or less: When you make profound changes in the GPS timing signal, the best approach to accurately recovering that signal has to change to match the new signal. Does everybody change everything the next day? Of course not. It takes a while for folks to work out what’s what with the “new rules”. Bob > On Oct 14, 2021, at 8:12 PM, Hal Murray wrote: > > > kb...@n1k.org said: >> The other way to look at it: The Z3801 and it???s kin basically went obsolete >> in 2000 when SA was turned off. Once that happened, the design approach >> changed. > > Could you please say more. What changed in the design approach? > > Can I tell the difference by looking at a box? Or poking at the serial port? > > > > -- > These are my opinions. I hate spam. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
kb...@n1k.org said: > The other way to look at it: The Z3801 and it???s kin basically went obsolete > in 2000 when SA was turned off. Once that happened, the design approach > changed. Could you please say more. What changed in the design approach? Can I tell the difference by looking at a box? Or poking at the serial port? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi The other way to look at it: The Z3801 and it’s kin basically went obsolete in 2000 when SA was turned off. Once that happened, the design approach changed. That, on top of whatever system life cycle issues applied pushed it onto the scrap heap. No, that’s not to say you should toss out your 3801’s. Only that it was no longer competitive for new designs. Bob > On Oct 14, 2021, at 6:48 PM, Magnus Danielson via time-nuts > wrote: > > Hi, > > It kind of depends. The Z3801A was really crafted to meet the needs of CDMA > mobile stations. That had it's life-span. Other GPSDOs can sit for very long > time and when they fail, much around them can have changed, or mostly things > have been added. > > It used to be that GPSes could be installed and no real intention to upgrade > existed. Some where even questionable if they could be upgraded during their > lifetime, where as others could maybe be upgraded in the field or at least > required the vendors service organisation being involved. Others was dead > easy to upgrade in the field by the user. Very few firms still support their > oldest devices, but it seems to be mostly because they can and they like the > challenge. For some reason, being able to upgrade it in the field, remotely > in secure way and still have support enough to do it has creeped into > requirements. I helped to push that. DHS published it and we just started an > IEEE standard for it. Little bit of a side-track, but never the less. > Awareness have increased. > > Cheers, > Magnus > > On 2021-10-12 18:58, Bob kb8tq wrote: >> Hi >> >> If a cell tower is running for 5 years without an upgrade, that’s doing >> pretty well. >> Ten years is an eternity in this case. Even for core network stuff, the >> “expected >> lifetime” in the spec rarely makes it to 20 years and pretty much never goes >> past >> that (in the spec.). Does the stuff last longer? In some cases it most >> certainly does. >> Is the firmware still supported after X years? ….. h…. >> >> One way to “see” this is to take a look at the date codes on this gear as it >> shows >> up on eBay. The 3801’s headed out into the field in the late 90’s and became >> a >> “thing” for Time Nuts to buy and poke at by the early 2000’s. >> >> How you factor in the delay between being pulled out of service in who knows >> where, auctioned off, shipped to China, parted out, parts resold, and listed >> on eBay is >> unclear. I’d bet they go by slow boat heading over there …. >> >> Bob >> >>> On Oct 12, 2021, at 12:27 PM, Hal Murray >>> wrote: >>> >>> >>> kb...@n1k.org said: I???ve run 3801???s for years and years without ever power cycling them. Other than power supply failure, they never had a problem. They did get detailed monitoring pretty much all the time. >>> I was guessing that the reboot-every-few-months recipe was trying to dance >>> around the week number roll over issue. >>> >>> Has anybody figured out where/when it writes whatever it needs so that it >>> comes up right on power up? >>> >>> On the initial application (cell towers?), was there any expectation of >>> lifetime? In particular were they expected to keep going over WNRO and/or >>> was >>> there a difference between run over WNRO and spares sitting on the shelf >>> coming up after WNRO? >>> >>> -- >>> These are my opinions. I hate spam. >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >>> an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >> email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi, It kind of depends. The Z3801A was really crafted to meet the needs of CDMA mobile stations. That had it's life-span. Other GPSDOs can sit for very long time and when they fail, much around them can have changed, or mostly things have been added. It used to be that GPSes could be installed and no real intention to upgrade existed. Some where even questionable if they could be upgraded during their lifetime, where as others could maybe be upgraded in the field or at least required the vendors service organisation being involved. Others was dead easy to upgrade in the field by the user. Very few firms still support their oldest devices, but it seems to be mostly because they can and they like the challenge. For some reason, being able to upgrade it in the field, remotely in secure way and still have support enough to do it has creeped into requirements. I helped to push that. DHS published it and we just started an IEEE standard for it. Little bit of a side-track, but never the less. Awareness have increased. Cheers, Magnus On 2021-10-12 18:58, Bob kb8tq wrote: Hi If a cell tower is running for 5 years without an upgrade, that’s doing pretty well. Ten years is an eternity in this case. Even for core network stuff, the “expected lifetime” in the spec rarely makes it to 20 years and pretty much never goes past that (in the spec.). Does the stuff last longer? In some cases it most certainly does. Is the firmware still supported after X years? ….. h…. One way to “see” this is to take a look at the date codes on this gear as it shows up on eBay. The 3801’s headed out into the field in the late 90’s and became a “thing” for Time Nuts to buy and poke at by the early 2000’s. How you factor in the delay between being pulled out of service in who knows where, auctioned off, shipped to China, parted out, parts resold, and listed on eBay is unclear. I’d bet they go by slow boat heading over there …. Bob On Oct 12, 2021, at 12:27 PM, Hal Murray wrote: kb...@n1k.org said: I???ve run 3801???s for years and years without ever power cycling them. Other than power supply failure, they never had a problem. They did get detailed monitoring pretty much all the time. I was guessing that the reboot-every-few-months recipe was trying to dance around the week number roll over issue. Has anybody figured out where/when it writes whatever it needs so that it comes up right on power up? On the initial application (cell towers?), was there any expectation of lifetime? In particular were they expected to keep going over WNRO and/or was there a difference between run over WNRO and spares sitting on the shelf coming up after WNRO? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi If a cell tower is running for 5 years without an upgrade, that’s doing pretty well. Ten years is an eternity in this case. Even for core network stuff, the “expected lifetime” in the spec rarely makes it to 20 years and pretty much never goes past that (in the spec.). Does the stuff last longer? In some cases it most certainly does. Is the firmware still supported after X years? ….. h…. One way to “see” this is to take a look at the date codes on this gear as it shows up on eBay. The 3801’s headed out into the field in the late 90’s and became a “thing” for Time Nuts to buy and poke at by the early 2000’s. How you factor in the delay between being pulled out of service in who knows where, auctioned off, shipped to China, parted out, parts resold, and listed on eBay is unclear. I’d bet they go by slow boat heading over there …. Bob > On Oct 12, 2021, at 12:27 PM, Hal Murray wrote: > > > kb...@n1k.org said: >> I???ve run 3801???s for years and years without ever power cycling them. >> Other >> than power supply failure, they never had a problem. They did get detailed >> monitoring pretty much all the time. > > I was guessing that the reboot-every-few-months recipe was trying to dance > around the week number roll over issue. > > Has anybody figured out where/when it writes whatever it needs so that it > comes up right on power up? > > On the initial application (cell towers?), was there any expectation of > lifetime? In particular were they expected to keep going over WNRO and/or > was > there a difference between run over WNRO and spares sitting on the shelf > coming up after WNRO? > > -- > These are my opinions. I hate spam. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
kb...@n1k.org said: > I???ve run 3801???s for years and years without ever power cycling them. Other > than power supply failure, they never had a problem. They did get detailed > monitoring pretty much all the time. I was guessing that the reboot-every-few-months recipe was trying to dance around the week number roll over issue. Has anybody figured out where/when it writes whatever it needs so that it comes up right on power up? On the initial application (cell towers?), was there any expectation of lifetime? In particular were they expected to keep going over WNRO and/or was there a difference between run over WNRO and spares sitting on the shelf coming up after WNRO? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi The 3081 takes a *long* time to get to it’s final “settled” state on it’s control loop. How long is a “that depends” sort of thing, but even for short interruptions, it can be weeks. Cycling it puts you right back into the start of the process. If you have a defective receiver, then replacing it sounds like the better answer. Bob > On Oct 12, 2021, at 11:10 AM, Björn wrote: > > Hi Bob, > > Agree with others - is has been discussed here at the list that these ancient > Oncore receivers have this issue. Not all of them, but some. This has nothing > to do with the original use case and the systems was shifted out of cell > tower applications a long time ago. > > Kind regards > > Björn > > Sent from my iPhone > >> On 12 Oct 2021, at 16:58, Bob kb8tq wrote: >> >> Hi >> >> I’m not suggesting that there is no issue. If this had been >> known to the original designers or users, routine shutdowns >> and restarts would have been a show stopper. >> >> I’ve run 3801’s for years and years without ever power cycling >> them. Other than power supply failure, they never had a >> problem. They did get detailed monitoring pretty much all >> the time. >> >> Bob >> >>> On Oct 12, 2021, at 10:26 AM, CFO wrote: >>> On 12/10/2021 14.53, Bob kb8tq wrote: Hi You can be pretty sure that in their original installations as a reference for a cell tower, shutting the whole thing down every couple months was not part of the spec. Bob >>> I read over on the Z3801A site (forum) , that it seems like that GPS >>> receiver oscillator would drift , wo. these shutdown/calibrate steps. >>> That would make the receiver drift and be more and more insensitive over >>> time , and eventually loose sync. >>> >>> This oscillator is not to be confused with the HP DOCXO. >>> >>> CFO >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >>> an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >> email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi Bob, Agree with others - is has been discussed here at the list that these ancient Oncore receivers have this issue. Not all of them, but some. This has nothing to do with the original use case and the systems was shifted out of cell tower applications a long time ago. Kind regards Björn Sent from my iPhone > On 12 Oct 2021, at 16:58, Bob kb8tq wrote: > > Hi > > I’m not suggesting that there is no issue. If this had been > known to the original designers or users, routine shutdowns > and restarts would have been a show stopper. > > I’ve run 3801’s for years and years without ever power cycling > them. Other than power supply failure, they never had a > problem. They did get detailed monitoring pretty much all > the time. > > Bob > >> On Oct 12, 2021, at 10:26 AM, CFO wrote: >> >>> On 12/10/2021 14.53, Bob kb8tq wrote: >>> Hi >>> >>> You can be pretty sure that in their original installations >>> as a reference for a cell tower, shutting the whole thing >>> down every couple months was not part of the spec. >>> >>> Bob >> I read over on the Z3801A site (forum) , that it seems like that GPS >> receiver oscillator would drift , wo. these shutdown/calibrate steps. >> That would make the receiver drift and be more and more insensitive over >> time , and eventually loose sync. >> >> This oscillator is not to be confused with the HP DOCXO. >> >> CFO >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >> email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi I’m not suggesting that there is no issue. If this had been known to the original designers or users, routine shutdowns and restarts would have been a show stopper. I’ve run 3801’s for years and years without ever power cycling them. Other than power supply failure, they never had a problem. They did get detailed monitoring pretty much all the time. Bob > On Oct 12, 2021, at 10:26 AM, CFO wrote: > > On 12/10/2021 14.53, Bob kb8tq wrote: >> Hi >> >> You can be pretty sure that in their original installations >> as a reference for a cell tower, shutting the whole thing >> down every couple months was not part of the spec. >> >> Bob > I read over on the Z3801A site (forum) , that it seems like that GPS receiver > oscillator would drift , wo. these shutdown/calibrate steps. > That would make the receiver drift and be more and more insensitive over time > , and eventually loose sync. > > This oscillator is not to be confused with the HP DOCXO. > > CFO > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
On 12/10/2021 14.53, Bob kb8tq wrote: Hi You can be pretty sure that in their original installations as a reference for a cell tower, shutting the whole thing down every couple months was not part of the spec. Bob I read over on the Z3801A site (forum) , that it seems like that GPS receiver oscillator would drift , wo. these shutdown/calibrate steps. That would make the receiver drift and be more and more insensitive over time , and eventually loose sync. This oscillator is not to be confused with the HP DOCXO. CFO ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Hi You can be pretty sure that in their original installations as a reference for a cell tower, shutting the whole thing down every couple months was not part of the spec. Bob > On Oct 12, 2021, at 12:47 AM, CFO wrote: > > My Z3810 had begun to show Alarm on the GPS receiver. On Coldstart it seems like it lives for 10min or so , and the enters alarm state. I'm quite sure it's the GPS receiver that has gone to "heaven" , never got that "Coldstart" every 6 months incorporated in my routines > Well (Oopz - It is a Z3801A i have) > > I dug out the Z3801 from storage (10 months), gave it a new 48V PSU and > started it up. > To my surprise it locked to 3 sats, after a few hours. And is now happily > humming away. > I did "quick" test the old 48V PSU, loaded with 600mA. And it keept the 48V > fine, doubt it was the cause. > > The "Lady" (Heather) shows that, The "Old Lady" (Z3801A) has 122700 active > hours (14yr) > Maybe it was the GPS oscillator that needed that restart, as per the service > note. > > https://synergy-gps.com/wp-content/uploads/2019/06/VP_SERVICE_NOTE.pdf > ** SNIP ** > Turn off all power to the GPS unit. The unit must be completely powered down > for > at least two minutes. After two minutes, turn the power on. > > This procedure should be performed every three to six months. This will allow > the unit > to perform a self-diagnostic routine and recalibrate an internal component > for optimal > performance. > ** SNIP *** > > The SN explicit says "Turn off all power for minimum 2 min", would that have > influence on the OCXO stability ? > Wonder why a : *TST - Would not do it (The reboot & cal) .. Anyone have an > idea ? > > > Thank you goes to the nice person that off-list offered to have a look in the > "drawer" for a VP. > Let's see if it's still needed. > > > CFO > Denmark > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
My Z3810 had begun to show Alarm on the GPS receiver. On Coldstart it seems like it lives for 10min or so , and the enters alarm state. I'm quite sure it's the GPS receiver that has gone to "heaven" , never got that "Coldstart" every 6 months incorporated in my routines Well (Oopz - It is a Z3801A i have) I dug out the Z3801 from storage (10 months), gave it a new 48V PSU and started it up. To my surprise it locked to 3 sats, after a few hours. And is now happily humming away. I did "quick" test the old 48V PSU, loaded with 600mA. And it keept the 48V fine, doubt it was the cause. The "Lady" (Heather) shows that, The "Old Lady" (Z3801A) has 122700 active hours (14yr) Maybe it was the GPS oscillator that needed that restart, as per the service note. https://synergy-gps.com/wp-content/uploads/2019/06/VP_SERVICE_NOTE.pdf ** SNIP ** Turn off all power to the GPS unit. The unit must be completely powered down for at least two minutes. After two minutes, turn the power on. This procedure should be performed every three to six months. This will allow the unit to perform a self-diagnostic routine and recalibrate an internal component for optimal performance. ** SNIP *** The SN explicit says "Turn off all power for minimum 2 min", would that have influence on the OCXO stability ? Wonder why a : *TST - Would not do it (The reboot & cal) .. Anyone have an idea ? Thank you goes to the nice person that off-list offered to have a look in the "drawer" for a VP. Let's see if it's still needed. CFO Denmark ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
On 10/10/2021 13.04, Gerhard Hoffmann wrote: Am 08.10.21 um 15:26 schrieb CFO: My Z3810 had begun to show Alarm on the GPS receiver. On Coldstart it seems like it lives for 10min or so , and the enters alarm state. I'm quite sure it's the GPS receiver that has gone to "heaven" , never got that "Coldstart" every 6 months incorporated in my routines A span of 10 minutes from cold points more towards the oven. Maybe it stays too far away from the exact frequency so that a lock is impossible. There would be no reason to complain as long as the oven is cold. Gerhard I had the unit running (it was in error state) , and powered it off for a minute , then on. Then it locked (i saw sats) , and went into error again after approx 10 min , now i didn't see any sats. I tried that 3..4 times , with the same result. Will dig it out of storage, and try some more CFO ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP
Am 08.10.21 um 15:26 schrieb CFO: My Z3810 had begun to show Alarm on the GPS receiver. On Coldstart it seems like it lives for 10min or so , and the enters alarm state. I'm quite sure it's the GPS receiver that has gone to "heaven" , never got that "Coldstart" every 6 months incorporated in my routines A span of 10 minutes from cold points more towards the oven. Maybe it stays too far away from the exact frequency so that a lock is impossible. There would be no reason to complain as long as the oven is cold. cheers, Gerhard ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
