HI SMA multi output Mini Circuits splitters are dirt cheap on eBay if you shop a bit. The same is true of SMA DC blocks. If you need to adapt to some other connector, those adapters are pretty cheap as well. Net result is that you can come up with a “distribution system” for not a lot of money. The typical antenna has a pre-amp that is designed for a lot of cable loss. Use less cable or lower loss cable …. you have the gain to drive a passive distribution setup. Not low enough loss in the cable? Buy a single gain block to put in front of the splitter ….. Still dirt cheap. Bob > On Dec 28, 2024, at 12:18 PM, rbenward--- via time-nuts <time-nuts@lists.febo.com> wrote: > > Hi Wilko, > A distribution amp was on my list, as I only have two antennas but three RXs. So far, I plugged in the Z3801A at 12:03 EST, and it grabbed one satellite almost immediately, and now it is up to five, at 12:15. This is after a 24hr off period. As of writing this, six sats popped up at 12:17. So I guess the antenna interference theory is in play here. > > Bob > > -----Original Message----- > From: Wilko Bulte <wkb@xs4all.nl> > Sent: Saturday, December 28, 2024 12:03 PM > To: rbenward@verizon.net > Cc: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com>; Gregory Beat <w9gb@icloud.com> > Subject: Re: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem > Importance: High > > hi Bob, > > An antenna distritbution amplifier is what I use here to feed two Samsung UCCM GPSDO, a Furuno GPSDO and some random ham related stuff like a Motorola Tetra radio w/ GPS and a WSPR transmitter. Sofar I have not encountered any mutual interference. I feed my antenna using a separate biasT, and have DC-blocks on the individual GPS receivers. Note that doing so might give you antenna fault alerts (i.e. the receiver sees no current flow to feed the active antenna). > > For a first experiment a passive splitter might do, with one of the GPSDO feeding the antenna, the others DC blocked. A 1:4 splitter is what I ran before I got my hands on the distribution amplifier. > > Wilko > >> On 28 Dec 2024, at 17:48, rbenward@verizon.net wrote: >> >> Hi Wilko, Michael, Steve,& others, >> You make a good point. I remember when they prohibited any type of receiver on an airplane. Any receiver can leak their local oscillator frequency out the antenna connector, and that would include GPS. S parameters would indicate how much signal can leak from the antenna amplifier output to the actual antenna and eventually radiate. And of course, as you said, the antenna amplifier can oscillate... >> >> My antennas are separated vertically by about 3ft. I have them on a rope that I haul up a tree. My house has foil-based insulation and since the antennas are on the north side of the house, I need them to clear the roofline. The tree is high enough that the antennas "see" under the tree. I am at 40deg latitude. >> >> Maybe an antenna distribution amplifier/splitter is in order? I will conduct the experiment and off the Trimble GPS while the Z380x boots up. >> >> Thanks all, >> Bob >> >> >> >> -----Original Message----- >> From: Wilko Bulte <wkb@xs4all.nl> >> Sent: Friday, December 27, 2024 5:38 PM >> To: Discussion of precise time and frequency measurement >> <time-nuts@lists.febo.com> >> Cc: Gregory Beat <w9gb@icloud.com>; rbenward@verizon.net >> Subject: Re: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover >> Problem >> Importance: High >> >> Bob, >> >> Have you tried running only one antenna at a time? Reason why I ask is I recently had an interesting discussion with a ham operator who had (in his work, airport instrument landing systems) encountered a rogue GPS antenna who *emitted* signals on the GPS frequencies. Apparantly the antenna's amplifier had started to oscillate, turning that antenna into a rather effective GPS jammer. As you can imagine this is a rather slim chance, at the same time a bitch to figure out. >> >> just my $0,02 of course. >> >> Wilko >> >>> On 27 Dec 2024, at 20:46, rbenward--- via time-nuts <time-nuts@lists.febo.com> wrote: >>> >>> Hi Greg, >>> Thanks for this information. I will follow through on this in January. For some reason, the lock of the GPS satellites are really bad with my Motorola receivers. I have two active GPS antennas outside on a pulley that I haul up a tree. With the antennas on the north side of the house, and being at 40deg latitude, I need them way up there to clear my roof, as the walls of the house have foil insulation. The tree is pretty high so the antennas can see underneath. It sounds unorthodox, but it works. Sometimes it takes a day for the GPS receivers to lock up. No rhyme or reason, but turning everything off, including the GPS program, seems to help. Sometimes I can track three or four satellites, but status page has no ALT or AZ information, and the GPSDO just sits there constantly adjusting frequency. Once locked up they behave quite well. >>> >>> I am wrapping up my testing of the adapter board for the Oscilloquartz/UCT 8663 OCXOs. They seem to work OK, so I will be getting rid of the extra boards soon. My 10811 is near the end of travel with the internal adjustment, so I think I will be replacing it with the 8663 OCXO. >>> >>> Thanks again, >>> Bob >>> >>> -----Original Message----- >>> From: Gregory Beat via time-nuts <time-nuts@lists.febo.com> >>> Sent: Thursday, December 26, 2024 12:47 PM >>> To: rbenward@verizon.net; time-nuts@lists.febo.com >>> Cc: Discussion of precise time and frequency measurement >>> <time-nuts@lists.febo.com>; Gregory Beat <w9gb@icloud.com> >>> Subject: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem >>> Importance: High >>> >>> uBlox stated the EOL their earlier “6” series modules earlier in >>> 2024; https://www.u-blox.com/en/product/neolea-6t >>> >>> Synergy products based on that series are ending, as noted. >>> April 24, 2024 announcement about LEA6 modules. >>> https://synergy-gps.com/wp-content/uploads/2024/04/EOL-Ublox-lea6-GPS >>> - >>> receiver.pdf >>> >>> Synergy stated they are transitioning to current uBlox LEA8 series. This was not unexpected, as uBlox stated intentions earlier (before COVID disruptions). >>> >>> uBlox GNSS chipsets >>> https://content.u-blox.com/sites/default/files/products/documents/GNS >>> S >>> -product_Overview_UBX-14000426.pdf >>> === >>> Gina Aspeytia, at Synergy can be reached via telephone at 858-566-0666, or e-Mail at gina@synergy-gps.com . She and Art can answer your concerns/questions and suggest an appropriate replacement Synergy GNSS solution, as well as data sheets and delivery availability. >>> — >>> Symmetricom bought the HP Time/Frequency Reference product line (x380xx); with just technology / firmware changes based on OEM parts availability. >>> >>> In my case, I provided inside photos of my late model 58503B (which worked fine, with appropriate SCPI commands) and talked to Art Sepin. >>> Since my WNRO event was recent, and this late HP/Symmetricom model had not been tested by Synergy, I loaned my 58503B to Art Sepin. >>> Rick Hambly performed “bench tests” of different Synergy solutions (+M12 replacement using existing Goshay adapter; UT+/VP replacement w/o Goshay adapter). >>> >>> Results with Synergy SSR were Faster locking to GPS constellation (<5 minutes); WNRO resolution; improved ADEV; and transparent operation with SatStat and Lady Heather. This was reported earlier this year (Feb 2024) on time-nuts. >>> >>> greg >>> >>>>> On Dec 26, 2024, at 10:07 AM, rbenward@verizon.net wrote: >>>> >>>> Hi Gregory, >>>> So, in a nutshell, you are saying I can drop in a Synergy/UBLOX RX with no modifications? According to the link, the SSR-6T+ has reached end of life. Are they making other drop ins or is this the end of their foray into Mototrola replacements? >>>> >>>> Both of my Z3805A/Z3801A GPSDOs are HP/Motorolas. Does this drop in apply, or is that only the Symmetricom units? >>>> >>>> Bob >>>> >>>> -----Original Message----- >>>> From: Gregory Beat via time-nuts <time-nuts@lists.febo.com> >>>> Sent: Wednesday, December 25, 2024 7:18 AM >>>> To: time-nuts@lists.febo.com >>>> Cc: Gregory Beat <w9gb@icloud.com> >>>> Subject: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem >>>> Importance: High >>>> >>>>  Bob - >>>> >>>> 10 years ago, Bob Camp and Magnus Danielson had a time-nuts thread discussing the versions of HP/Symmetricom GPSDO time/frequency references, with Magnus noting the firmware capabilities (FPGA). I am not aware of anyone “releasing” (open source) that information. >>>> https://febo.com/pipermail/time-nuts_lists.febo.com/2014-November/07 >>>> 1 >>>> 5 >>>> 07.html >>>> >>>> For my Symmetricom 58503B Reference (telco surplus), a late version, it internally used the same basic PC HP/Symmetricom PC board of the earlier models. However the antenna input section was BARE (No components for +5V injection, GPSantenna detection, etc.). The external GPS antenna connector (“N” female) was routed directly to a M12+ GPS board with an Goshay Adapter board for the (2x5-pin) header (for old Motorola Oncore VP/UT+ form factor). >>>> >>>> Upon further investigations by Art Sepin and Rick Hambly it was discovered that an additional response was required from the Synergy SSR receiver to a Symmetricom Reference request (@@) for full operation with this late 58503B model. >>>> BTW, the Synergy SSR receiver, using the uBlox chipset (multi-channel), chooses the “best in view” of the multiple satellites — and passes these onto the Symmetricom. >>>> The SSR then converts the data stream to Motorola binary. >>>> https://synergy-gps.com/wp-content/uploads/2022/05/SSR-VP-UT-and-GT- >>>> D >>>> r >>>> op-In-ReplacementsTN484-B030624.pdf >>>> >>>> Short Answer: A new uBlox receiver will provide faster locking operation, resolution to WNRO issue, access to larger “in view” satellites, and then choosing best 6, 8, or 12 satellites, while converting receiver data stream to the expected Motorola binary. >>>> >>>> Symmetricom firmware (FPGA), to my knowledge, has not been released for upgrades. >>>> >>>> gb >>>> == >>>> Date: Mon, 23 Dec 2024 13:10:33 -0500 >>>> From: <rbenward@verizon.net> >>>> Subject: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem >>>> To: "'Discussion of precise time and frequency measurement'" >>>> <time-nuts@lists.febo.com>, <timenut@mi7.us> >>>> Cc: 'Scott Qi' <scott.qi@gmail.com> >>>> >>>> Hi All, >>>> So how does someone get the firmware chips to make this GPS change? >>>> My Z3805A is using the Motorola GPS. >>>> I would love to upgrade to something with more channels. >>>> Does this change also apply to the Z3801A? >>>> >>>> Bob >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >>>> send an email to time-nuts-leave@lists.febo.com >>>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >>> send an email to time-nuts-leave@lists.febo.com >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >>> send an email to time-nuts-leave@lists.febo.com >> >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Bob, I agree with all of your suggestions/comments. Unless your cable is short, you always want an amplifier at the source. RG58 nets you about 8dB loss at 1.5GHz depending on the chart you look at. If you are looking to avoid an amplifier, you need a larger diameter style, low loss coax, like LMR400. A 4x splitter is another 6-7dB. A distributed system needs that extra wire and bias tees to provide power. A typical splitter is not equipped to pass DC, so you need to shop carefully. All those extra adapters, BNC to SMA, or to N, and the bias tees, as well as DC blocks, all add to the noise figure, especially at 1.5GHz, But, you know all of this, I guess I am just repeating it for others. In the end I just think it will be easier to use a dedicated GPS splitter and maybe a fat cable up to the antenna. So far, I've left the second antenna disconnected (Trimble). When I did connect it, the timing went off on the Z3801A, and I don't think it was a coincidence. That surprised me. I disconnected it, but the previous drift never recovered. I'm still deciding whether to move the antennas apart (and buy a third) or buy a dedicated GPS splitter. I am now burning in a new 8663 OCXO on my adapter board. We will see how that goes, but so far, so good. Thanks for your input, Bob -----Original Message----- From: Bob Camp via time-nuts <time-nuts@lists.febo.com> Sent: Saturday, December 28, 2024 7:45 PM To: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com> Cc: Bob Camp <kb8tq@n1k.org> Subject: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem Importance: High HI SMA multi output Mini Circuits splitters are dirt cheap on eBay if you shop a bit. The same is true of SMA DC blocks. If you need to adapt to some other connector, those adapters are pretty cheap as well. Net result is that you can come up with a “distribution system” for not a lot of money. The typical antenna has a pre-amp that is designed for a lot of cable loss. Use less cable or lower loss cable …. you have the gain to drive a passive distribution setup. Not low enough loss in the cable? Buy a single gain block to put in front of the splitter ….. Still dirt cheap. Bob > On Dec 28, 2024, at 12:18 PM, rbenward--- via time-nuts <time-nuts@lists.febo.com> wrote: > > Hi Wilko, > A distribution amp was on my list, as I only have two antennas but three RXs. So far, I plugged in the Z3801A at 12:03 EST, and it grabbed one satellite almost immediately, and now it is up to five, at 12:15. This is after a 24hr off period. As of writing this, six sats popped up at 12:17. So I guess the antenna interference theory is in play here. > > Bob > > -----Original Message----- > From: Wilko Bulte <wkb@xs4all.nl> > Sent: Saturday, December 28, 2024 12:03 PM > To: rbenward@verizon.net > Cc: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com>; Gregory Beat <w9gb@icloud.com> > Subject: Re: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover > Problem > Importance: High > > hi Bob, > > An antenna distritbution amplifier is what I use here to feed two Samsung UCCM GPSDO, a Furuno GPSDO and some random ham related stuff like a Motorola Tetra radio w/ GPS and a WSPR transmitter. Sofar I have not encountered any mutual interference. I feed my antenna using a separate biasT, and have DC-blocks on the individual GPS receivers. Note that doing so might give you antenna fault alerts (i.e. the receiver sees no current flow to feed the active antenna). > > For a first experiment a passive splitter might do, with one of the GPSDO feeding the antenna, the others DC blocked. A 1:4 splitter is what I ran before I got my hands on the distribution amplifier. > > Wilko > >> On 28 Dec 2024, at 17:48, rbenward@verizon.net wrote: >> >> Hi Wilko, Michael, Steve,& others, >> You make a good point. I remember when they prohibited any type of receiver on an airplane. Any receiver can leak their local oscillator frequency out the antenna connector, and that would include GPS. S parameters would indicate how much signal can leak from the antenna amplifier output to the actual antenna and eventually radiate. And of course, as you said, the antenna amplifier can oscillate... >> >> My antennas are separated vertically by about 3ft. I have them on a rope that I haul up a tree. My house has foil-based insulation and since the antennas are on the north side of the house, I need them to clear the roofline. The tree is high enough that the antennas "see" under the tree. I am at 40deg latitude. >> >> Maybe an antenna distribution amplifier/splitter is in order? I will conduct the experiment and off the Trimble GPS while the Z380x boots up. >> >> Thanks all, >> Bob >> >> >> >> -----Original Message----- >> From: Wilko Bulte <wkb@xs4all.nl> >> Sent: Friday, December 27, 2024 5:38 PM >> To: Discussion of precise time and frequency measurement >> <time-nuts@lists.febo.com> >> Cc: Gregory Beat <w9gb@icloud.com>; rbenward@verizon.net >> Subject: Re: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover >> Problem >> Importance: High >> >> Bob, >> >> Have you tried running only one antenna at a time? Reason why I ask is I recently had an interesting discussion with a ham operator who had (in his work, airport instrument landing systems) encountered a rogue GPS antenna who *emitted* signals on the GPS frequencies. Apparantly the antenna's amplifier had started to oscillate, turning that antenna into a rather effective GPS jammer. As you can imagine this is a rather slim chance, at the same time a bitch to figure out. >> >> just my $0,02 of course. >> >> Wilko >> >>> On 27 Dec 2024, at 20:46, rbenward--- via time-nuts <time-nuts@lists.febo.com> wrote: >>> >>> Hi Greg, >>> Thanks for this information. I will follow through on this in January. For some reason, the lock of the GPS satellites are really bad with my Motorola receivers. I have two active GPS antennas outside on a pulley that I haul up a tree. With the antennas on the north side of the house, and being at 40deg latitude, I need them way up there to clear my roof, as the walls of the house have foil insulation. The tree is pretty high so the antennas can see underneath. It sounds unorthodox, but it works. Sometimes it takes a day for the GPS receivers to lock up. No rhyme or reason, but turning everything off, including the GPS program, seems to help. Sometimes I can track three or four satellites, but status page has no ALT or AZ information, and the GPSDO just sits there constantly adjusting frequency. Once locked up they behave quite well. >>> >>> I am wrapping up my testing of the adapter board for the Oscilloquartz/UCT 8663 OCXOs. They seem to work OK, so I will be getting rid of the extra boards soon. My 10811 is near the end of travel with the internal adjustment, so I think I will be replacing it with the 8663 OCXO. >>> >>> Thanks again, >>> Bob >>> >>> -----Original Message----- >>> From: Gregory Beat via time-nuts <time-nuts@lists.febo.com> >>> Sent: Thursday, December 26, 2024 12:47 PM >>> To: rbenward@verizon.net; time-nuts@lists.febo.com >>> Cc: Discussion of precise time and frequency measurement >>> <time-nuts@lists.febo.com>; Gregory Beat <w9gb@icloud.com> >>> Subject: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem >>> Importance: High >>> >>> uBlox stated the EOL their earlier “6” series modules earlier in >>> 2024; https://www.u-blox.com/en/product/neolea-6t >>> >>> Synergy products based on that series are ending, as noted. >>> April 24, 2024 announcement about LEA6 modules. >>> https://synergy-gps.com/wp-content/uploads/2024/04/EOL-Ublox-lea6-GP >>> S >>> - >>> receiver.pdf >>> >>> Synergy stated they are transitioning to current uBlox LEA8 series. This was not unexpected, as uBlox stated intentions earlier (before COVID disruptions). >>> >>> uBlox GNSS chipsets >>> https://content.u-blox.com/sites/default/files/products/documents/GN >>> S >>> S >>> -product_Overview_UBX-14000426.pdf >>> === >>> Gina Aspeytia, at Synergy can be reached via telephone at 858-566-0666, or e-Mail at gina@synergy-gps.com . She and Art can answer your concerns/questions and suggest an appropriate replacement Synergy GNSS solution, as well as data sheets and delivery availability. >>> — >>> Symmetricom bought the HP Time/Frequency Reference product line (x380xx); with just technology / firmware changes based on OEM parts availability. >>> >>> In my case, I provided inside photos of my late model 58503B (which worked fine, with appropriate SCPI commands) and talked to Art Sepin. >>> Since my WNRO event was recent, and this late HP/Symmetricom model had not been tested by Synergy, I loaned my 58503B to Art Sepin. >>> Rick Hambly performed “bench tests” of different Synergy solutions (+M12 replacement using existing Goshay adapter; UT+/VP replacement w/o Goshay adapter). >>> >>> Results with Synergy SSR were Faster locking to GPS constellation (<5 minutes); WNRO resolution; improved ADEV; and transparent operation with SatStat and Lady Heather. This was reported earlier this year (Feb 2024) on time-nuts. >>> >>> greg >>> >>>>> On Dec 26, 2024, at 10:07 AM, rbenward@verizon.net wrote: >>>> >>>> Hi Gregory, >>>> So, in a nutshell, you are saying I can drop in a Synergy/UBLOX RX with no modifications? According to the link, the SSR-6T+ has reached end of life. Are they making other drop ins or is this the end of their foray into Mototrola replacements? >>>> >>>> Both of my Z3805A/Z3801A GPSDOs are HP/Motorolas. Does this drop in apply, or is that only the Symmetricom units? >>>> >>>> Bob >>>> >>>> -----Original Message----- >>>> From: Gregory Beat via time-nuts <time-nuts@lists.febo.com> >>>> Sent: Wednesday, December 25, 2024 7:18 AM >>>> To: time-nuts@lists.febo.com >>>> Cc: Gregory Beat <w9gb@icloud.com> >>>> Subject: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem >>>> Importance: High >>>> >>>>  Bob - >>>> >>>> 10 years ago, Bob Camp and Magnus Danielson had a time-nuts thread discussing the versions of HP/Symmetricom GPSDO time/frequency references, with Magnus noting the firmware capabilities (FPGA). I am not aware of anyone “releasing” (open source) that information. >>>> https://febo.com/pipermail/time-nuts_lists.febo.com/2014-November/0 >>>> 7 >>>> 1 >>>> 5 >>>> 07.html >>>> >>>> For my Symmetricom 58503B Reference (telco surplus), a late version, it internally used the same basic PC HP/Symmetricom PC board of the earlier models. However the antenna input section was BARE (No components for +5V injection, GPSantenna detection, etc.). The external GPS antenna connector (“N” female) was routed directly to a M12+ GPS board with an Goshay Adapter board for the (2x5-pin) header (for old Motorola Oncore VP/UT+ form factor). >>>> >>>> Upon further investigations by Art Sepin and Rick Hambly it was discovered that an additional response was required from the Synergy SSR receiver to a Symmetricom Reference request (@@) for full operation with this late 58503B model. >>>> BTW, the Synergy SSR receiver, using the uBlox chipset (multi-channel), chooses the “best in view” of the multiple satellites — and passes these onto the Symmetricom. >>>> The SSR then converts the data stream to Motorola binary. >>>> https://synergy-gps.com/wp-content/uploads/2022/05/SSR-VP-UT-and-GT >>>> - >>>> D >>>> r >>>> op-In-ReplacementsTN484-B030624.pdf >>>> >>>> Short Answer: A new uBlox receiver will provide faster locking operation, resolution to WNRO issue, access to larger “in view” satellites, and then choosing best 6, 8, or 12 satellites, while converting receiver data stream to the expected Motorola binary. >>>> >>>> Symmetricom firmware (FPGA), to my knowledge, has not been released for upgrades. >>>> >>>> gb >>>> == >>>> Date: Mon, 23 Dec 2024 13:10:33 -0500 >>>> From: <rbenward@verizon.net> >>>> Subject: [time-nuts] Re: Samsung-Symmetricom GPSDO Rollover Problem >>>> To: "'Discussion of precise time and frequency measurement'" >>>> <time-nuts@lists.febo.com>, <timenut@mi7.us> >>>> Cc: 'Scott Qi' <scott.qi@gmail.com> >>>> >>>> Hi All, >>>> So how does someone get the firmware chips to make this GPS change? >>>> My Z3805A is using the Motorola GPS. >>>> I would love to upgrade to something with more channels. >>>> Does this change also apply to the Z3801A? >>>> >>>> Bob >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >>>> send an email to time-nuts-leave@lists.febo.com >>>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >>> send an email to time-nuts-leave@lists.febo.com >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >>> send an email to time-nuts-leave@lists.febo.com >> >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send > an email to time-nuts-leave@lists.febo.com _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com