[time-nuts] Re: HP 5065A, no 2nd harmonic.
Hi, Your help is appreciated. We can keep this on-list for now I guess, on the chance it helps someone in the future. Jared. ‐‐‐ Original Message ‐‐‐ On Friday, November 19th, 2021 at 08:25, paul swed wrote: > Jared I would be happy to see if I can help remotely. We may want to take > this offline or not. Others may find it interesting. > Regards > Paul > WB8TSL > > On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts > wrote: > > > Hi all, > > > > I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd > > harmonic. > > My voltages are all ok, the physics package hasn't overheated and I have > > replaced the usual resistors on the lamp assembly (and it was running fine > > afterward for a while), the lamp illuminates, and I've done the procedure > > to remove cell flooding. > > All readings on the 'circuit check' switch are nominal, apart from the 2nd > > harmonic position. No matter what I do, I can no longer get it to raise > > above 0. > > However, when I first turn the unit on, the needle drops to 0 and flicks a > > little before settling on 0 and staying there. > > > > Can someone help me get this unit up and running again? > > > > Thanks! > > Jared___ > > 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. signature.asc Description: OpenPGP digital signature ___ 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 5065A, no 2nd harmonic.
Jared I would be happy to see if I can help remotely. We may want to take this offline or not. Others may find it interesting. Regards Paul WB8TSL On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts < time-nuts@lists.febo.com> wrote: > Hi all, > > I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd > harmonic. > My voltages are all ok, the physics package hasn't overheated and I have > replaced the usual resistors on the lamp assembly (and it was running fine > afterward for a while), the lamp illuminates, and I've done the procedure > to remove cell flooding. > All readings on the 'circuit check' switch are nominal, apart from the 2nd > harmonic position. No matter what I do, I can no longer get it to raise > above 0. > However, when I first turn the unit on, the needle drops to 0 and flicks a > little before settling on 0 and staying there. > > Can someone help me get this unit up and running again? > > Thanks! > Jared___ > 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: FS740 Thoughts?
Hi This is one of those classic examples of what marketing writes and what (once the beer is poured) engineering actually knows. If you dive into the grubby details of the filtering. Been there / done that with a number of these guys. It’s very much *not* set up for GPS. The hanging bridge stuff PHK mentions in a previous post is one example. The need to adapt the filter to the monitored results is another weak area. Just how and when this or that pops up varies, but it will pop up. Bob > On Nov 18, 2021, at 2:02 PM, Dana Whitlow wrote: > > Bob, I seem to remember reading in the manual on the PRS-10 where they > expounded > at length about how they took great pains to make the unit work well with > typical noisy > GPS PPS input. > > I'm using a CNS Clock II as my primary GPSDO, checking phase slippage with > respect > to my PRS-10 to make decisions about when (or when not) to manually tweak > the PRS-10. > The CNS seems awfully noisy to me, even though the mfr says that it has > strong hanging > bridge correction. I run the two 10 MHz signals through a quadrature > demodulator whose > I & Q outputs go into a 2-channel DSO running in extremely low "roll > mode". I take a glance > at it several times per day, with each glance showing me the most recent > ~4-hour history. > When I do tweak, I strive to set the PRS-10 about 1E-11 low in frequency, > which yields a > couple of months of hands-off operation before it drifts to 1E-11 on the > high side. For > now, that has to suffice. But I'd rather not have to pay so much attention > to it, which is > why I dream about buying a new PRS-10 with PPS locking capability. > > Dana > > > On Thu, Nov 18, 2021 at 8:47 AM Poul-Henning Kamp > wrote: > >> >> Bob kb8tq writes: >> >>> The 'filter' in the PRS-10 is not really set up for a GPS sort of signal. >> >> It is particularly bad at handling GPS's because of the "hanging bridge" >> phenomena, and the better the GPS, the worse the result... >> >> I tried injecting the "negative sawtooth" via the serial port to my >> PRS10 but firmware features/bugs prevented that. >> >> The offset could only be changed permanently in the saved configuration, >> you could not change the running value on a second to second basis. >> >> -- >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >> p...@freebsd.org | TCP/IP since RFC 956 >> FreeBSD committer | BSD since 4.3-tahoe >> Never attribute to malice what can adequately be explained by incompetence. >> ___ >> 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: FS740 Thoughts?
Bob, I seem to remember reading in the manual on the PRS-10 where they expounded at length about how they took great pains to make the unit work well with typical noisy GPS PPS input. I'm using a CNS Clock II as my primary GPSDO, checking phase slippage with respect to my PRS-10 to make decisions about when (or when not) to manually tweak the PRS-10. The CNS seems awfully noisy to me, even though the mfr says that it has strong hanging bridge correction. I run the two 10 MHz signals through a quadrature demodulator whose I & Q outputs go into a 2-channel DSO running in extremely low "roll mode". I take a glance at it several times per day, with each glance showing me the most recent ~4-hour history. When I do tweak, I strive to set the PRS-10 about 1E-11 low in frequency, which yields a couple of months of hands-off operation before it drifts to 1E-11 on the high side. For now, that has to suffice. But I'd rather not have to pay so much attention to it, which is why I dream about buying a new PRS-10 with PPS locking capability. Dana On Thu, Nov 18, 2021 at 8:47 AM Poul-Henning Kamp wrote: > > Bob kb8tq writes: > > > The 'filter' in the PRS-10 is not really set up for a GPS sort of signal. > > It is particularly bad at handling GPS's because of the "hanging bridge" > phenomena, and the better the GPS, the worse the result... > > I tried injecting the "negative sawtooth" via the serial port to my > PRS10 but firmware features/bugs prevented that. > > The offset could only be changed permanently in the saved configuration, > you could not change the running value on a second to second basis. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > ___ > 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] HP 5065A, no 2nd harmonic.
Hi all, I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd harmonic. My voltages are all ok, the physics package hasn't overheated and I have replaced the usual resistors on the lamp assembly (and it was running fine afterward for a while), the lamp illuminates, and I've done the procedure to remove cell flooding. All readings on the 'circuit check' switch are nominal, apart from the 2nd harmonic position. No matter what I do, I can no longer get it to raise above 0. However, when I first turn the unit on, the needle drops to 0 and flicks a little before settling on 0 and staying there. Can someone help me get this unit up and running again? Thanks! Jared signature.asc Description: OpenPGP digital signature ___ 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: FS740 Thoughts?
Bob kb8tq writes: > The 'filter' in the PRS-10 is not really set up for a GPS sort of signal. It is particularly bad at handling GPS's because of the "hanging bridge" phenomena, and the better the GPS, the worse the result... I tried injecting the "negative sawtooth" via the serial port to my PRS10 but firmware features/bugs prevented that. The offset could only be changed permanently in the saved configuration, you could not change the running value on a second to second basis. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] FS740
I see the SRS FS 740 and Morion Rb's and super low Av OCXO's in al my Microwave publications. That seems the market the are after. Bert Kehren ___ 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: FS740 Thoughts?
Hi The 5 Hz (or whatever) switching and the hump definitely both originate in the same “feature” of the design. Does disabling the switching nuke the hump? If one has a PRS-10 I’d say it’s well worth trying. The “filter” in the PRS-10 is not really set up for a GPS sort of signal. It’s designed to handle a nice clean lab generated 1 pps. It’s there to lock the device up as part of a calibration routine. The 1 pps sync setups on other Rb’s are designed with the same target in mind. Bob > On Nov 18, 2021, at 7:50 AM, Dana Whitlow wrote: > > Poul, > > You did not really answer the basic question: "Does the 2.5 Hz > (or 5 Hz if applicable) C-field reversal cause the 2-sec bump in > the ADEV plot for the PRS-10?". > > BTW, some radio hams are involved with microwave and even > MMW communications between mobile stations, and I'd bet they > benefit quite a bit from any scheme that reduces magnetic field > sensitivity of their frequency references. Therefore, the C-field > reversal thing cannot be *all* bad. > > DanaK8YUM > > > Dana > > > On Thu, Nov 18, 2021 at 2:41 AM Poul-Henning Kamp > wrote: > >> >> Matt Huszagh writes: >>> "Poul-Henning Kamp" writes: >>> The PRS-10 switches the polarity of the C-field solenoid at 5Hz to cancel out varying external magnetic fields. If that is not a concern for you, for instance because you use it in a stationary application, it can be disabled with the "MS0" command. It's all in the manual. >>> >>> How does the 5Hz switching relate to the 2s hump in the ADEV plot? >> >> The manual says: >> >>"[...]the current in the coil is switched at a 5 Hz rate." >> >> You can either read that as: >> >>"There are five positive and five negative periods every second" >> >> or >>"The sign changes five times per second" >> >> It is not entirely obvious which reading is the correct one. >> >> When I experimented with it ages ago, I concluded the latter fit >> my data best, but that was a pretty early firmware version, with >> quite a number of variances from the manual. >> >> If your ambient magnetic field is stable, and it should be for >> time-nuts purposes, modulating the hyperfine transition is a bad >> idea, no matter the frequency. >> >> -- >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >> p...@freebsd.org | TCP/IP since RFC 956 >> FreeBSD committer | BSD since 4.3-tahoe >> Never attribute to malice what can adequately be explained by incompetence. >> > ___ > 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: time-nuts Digest, Vol 211, Issue 26
Hello, We can do much better ADEV and phase noise than the FS740. But much more expensive 2 to 4 times as much. SRS products are incredibly low price. I can't complete on price but do better with performance and flexibility. Best Regards Martyn ___ 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: FS740 Thoughts?
Dana Whitlow writes: > You did not really answer the basic question: "Does the 2.5 Hz > (or 5 Hz if applicable) C-field reversal cause the 2-sec bump in > the ADEV plot for the PRS-10?". I cannot answer that question as stated. My PRS10 died years ago, all I can say is that when I commissioned it, I disabled the MS because it improved things. > BTW, some radio hams are involved with microwave and even > MMW communications between mobile stations, [...] In any mobile application, or other application where the magnetic field is not nearly contant (for instance behind a steel door in a outdoor base-station cabinet, I would absolutely keep MS on. But for a time-nut installation, where the location is fixed, temperature controlled and, I would assume, due consideration is given to also keep the magnetic field from slamming around, I suggest MS be disabled. But it's a really trivial experiment to perform, so do it, measure and decide what is right for you. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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: FS740 Thoughts?
Poul, You did not really answer the basic question: "Does the 2.5 Hz (or 5 Hz if applicable) C-field reversal cause the 2-sec bump in the ADEV plot for the PRS-10?". BTW, some radio hams are involved with microwave and even MMW communications between mobile stations, and I'd bet they benefit quite a bit from any scheme that reduces magnetic field sensitivity of their frequency references. Therefore, the C-field reversal thing cannot be *all* bad. DanaK8YUM Dana On Thu, Nov 18, 2021 at 2:41 AM Poul-Henning Kamp wrote: > > Matt Huszagh writes: > > "Poul-Henning Kamp" writes: > > > > > The PRS-10 switches the polarity of the C-field solenoid at 5Hz to > > > cancel out varying external magnetic fields. > > > > > > If that is not a concern for you, for instance because you use it > > > in a stationary application, it can be disabled with the "MS0" command. > > > > > > It's all in the manual. > > > > How does the 5Hz switching relate to the 2s hump in the ADEV plot? > > The manual says: > > "[...]the current in the coil is switched at a 5 Hz rate." > > You can either read that as: > > "There are five positive and five negative periods every second" > > or > "The sign changes five times per second" > > It is not entirely obvious which reading is the correct one. > > When I experimented with it ages ago, I concluded the latter fit > my data best, but that was a pretty early firmware version, with > quite a number of variances from the manual. > > If your ambient magnetic field is stable, and it should be for > time-nuts purposes, modulating the hyperfine transition is a bad > idea, no matter the frequency. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > ___ 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: FS740 Thoughts?
Matt Huszagh writes: > "Poul-Henning Kamp" writes: > > > The PRS-10 switches the polarity of the C-field solenoid at 5Hz to > > cancel out varying external magnetic fields. > > > > If that is not a concern for you, for instance because you use it > > in a stationary application, it can be disabled with the "MS0" command. > > > > It's all in the manual. > > How does the 5Hz switching relate to the 2s hump in the ADEV plot? The manual says: "[...]the current in the coil is switched at a 5 Hz rate." You can either read that as: "There are five positive and five negative periods every second" or "The sign changes five times per second" It is not entirely obvious which reading is the correct one. When I experimented with it ages ago, I concluded the latter fit my data best, but that was a pretty early firmware version, with quite a number of variances from the manual. If your ambient magnetic field is stable, and it should be for time-nuts purposes, modulating the hyperfine transition is a bad idea, no matter the frequency. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
