Re: [time-nuts] PRS-10 input and output calibrations
In message CAL8XPmO0Wj2AUW8Q=-DrDGGDMdhTsteVJaMKgkXktgq=0j4...@mail.gmail.com , Azelio Boriani writes: That is very interesting in my opinion and, for those who have access to more than one PRS10, further investigation should be done. I had a new PRS10 and, just out-of-the-box, it locked (not instantly, of course) to the HP53508 PPS. There are threel obvious issues: Which flank you trigger on and which polarity and width the output pulse has. The output pulse from the PRS10 is pretty narrow, making it very easy to mistakenly use the wrong flank. -- 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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PRS-10 input and output calibrations
In message 4f947ff0.8070...@rubidium.dyndns.org, Magnus Danielson writes: On 04/22/2012 10:47 PM, b...@lysator.liu.se wrote: Interlocking two oscillators like that might be a really bad idea, as the PLL will have a gain, so risk having a gain loop, especially when the oscillators have the same default parameters being setup. You would clearly want to torque the timeconstant of the second PRS10 in that scenario, but idea is not without merit. -- 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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] FS700 is Z80 based ?
I guess I must have confused the FS700 with MegaPulses receiver, I always thought the FS700 was DSP based, but now that I read the manual I see that it is based on a Z80... Anyone have a copy of the EPROM ? -- 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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Seek Philips PM6612 Servicemanual
Hi T'Nuts I have inherited a Philips PM6612 80Mhz Counter. Basically it seems to work , i just did a quick test with 1 10Mhz. But all the low/bottom segments are off/dead. --- | | --- | | ^ | Bottom segment dead on all 9 digits I think it's prob. a bad connection , or a dead driver/transistor. And a manual or the part with the display drivers would be helpfull. I have searched the web , but couldn't find anything on the display. CFO - Tnut beginner Denmark ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FS700 is Z80 based ?
yes and put them on the KO4bb site for safe keeping. Do not recall the version Regards Paul WB8TSL On Mon, Apr 23, 2012 at 6:58 AM, Poul-Henning Kamp p...@phk.freebsd.dkwrote: I guess I must have confused the FS700 with MegaPulses receiver, I always thought the FS700 was DSP based, but now that I read the manual I see that it is based on a Z80... Anyone have a copy of the EPROM ? -- 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@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] Thunderbolt Question
I have been using a surplus Thunderbolt for about six months, and it seemed to be working fine. In January 2012, a message came up in yellow, (LEAP PENDING!), I don't know what this means, but since it didn't go away on Feb 28, must not be leap year related. About a week ago I got a Holdover: xx secs, message. It was a new figure in yellow. Yesterday the Thunderbolt stopped working correctly, there were no satellites found. I tried Lady Heather, and Trimble Studio without success.I finally got the unit back in service with a program called Tboltmon.exe. After it was running for a couple of hours I restarted Lady Heather. This morning I again have Holdover: 50 secs. Does it sound normal, or is this unit headed for the junk box? Sorry, I am not very technical about this type of electronics. You can see a snapshot of Lady Heather at: http://wa6rzw.homelinux.net/addon/fmt/fmt_2.php Any comments or suggestions would be appreciated. 73 Ed, WA6RZW ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Question
Maybe it's the antenna, or a short in the cable (water in the coax) or a nearby transmitters that is jamming the GPS signal. The simplest way to diagnose the problem is by swapping parts.Is your antenna in a good location with a direct view of the entire sky? On Mon, Apr 23, 2012 at 9:05 AM, Ed Mersich wa6...@comcast.net wrote: I have been using a surplus Thunderbolt for about six months, and it seemed to be working fine. In January 2012, a message came up in yellow, (LEAP PENDING!), I don't know what this means, but since it didn't go away on Feb 28, must not be leap year related. About a week ago I got a Holdover: xx secs, message. It was a new figure in yellow. Yesterday the Thunderbolt stopped working correctly, there were no satellites found. I tried Lady Heather, and Trimble Studio without success.I finally got the unit back in service with a program called Tboltmon.exe. After it was running for a couple of hours I restarted Lady Heather. This morning I again have Holdover: 50 secs. Does it sound normal, or is this unit headed for the junk box? Sorry, I am not very technical about this type of electronics. You can see a snapshot of Lady Heather at: http://wa6rzw.homelinux.net/addon/fmt/fmt_2.php Any comments or suggestions would be appreciated. 73 Ed, WA6RZW ___ 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. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Question
There is a leap second waiting for June/July this year. On Mon, Apr 23, 2012 at 6:16 PM, Chris Albertson albertson.ch...@gmail.comwrote: Maybe it's the antenna, or a short in the cable (water in the coax) or a nearby transmitters that is jamming the GPS signal. The simplest way to diagnose the problem is by swapping parts.Is your antenna in a good location with a direct view of the entire sky? On Mon, Apr 23, 2012 at 9:05 AM, Ed Mersich wa6...@comcast.net wrote: I have been using a surplus Thunderbolt for about six months, and it seemed to be working fine. In January 2012, a message came up in yellow, (LEAP PENDING!), I don't know what this means, but since it didn't go away on Feb 28, must not be leap year related. About a week ago I got a Holdover: xx secs, message. It was a new figure in yellow. Yesterday the Thunderbolt stopped working correctly, there were no satellites found. I tried Lady Heather, and Trimble Studio without success.I finally got the unit back in service with a program called Tboltmon.exe. After it was running for a couple of hours I restarted Lady Heather. This morning I again have Holdover: 50 secs. Does it sound normal, or is this unit headed for the junk box? Sorry, I am not very technical about this type of electronics. You can see a snapshot of Lady Heather at: http://wa6rzw.homelinux.net/addon/fmt/fmt_2.php Any comments or suggestions would be appreciated. 73 Ed, WA6RZW ___ 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. -- Chris Albertson Redondo Beach, California ___ 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.
Re: [time-nuts] Thunderbolt Question
I have been using a surplus Thunderbolt for about six months, and it seemed to be working fine. In January 2012, a message came up in yellow, (LEAP PENDING!), I don't know what this means, but since it didn't go away on Feb 28, must not be leap year related. Hi Ed, Right, in this case the LEAP refers to a leap second, not a leap year. When the next leap second occurs this summer, the yellow warning will go away. As you know, leap years are used to keep days and years in sync, where a day is earth rotation (about its axis) and a year is earth revolution (around the sun). Last one was: Feb 29, 2012. Similarly, leap seconds are used to keep seconds and days in sync, where a second is now defined by atomic standards and a day is earth rotation. Next one is: 19:59:60 EDT, Jun 30, 2012. Keeping clocks in sync is a significant part of the timekeeping world. For example, with quartz and GPS it's easy to discipline quartz in order to steer it closer to GPS. This is done by making slight changes in quartz EFC voltage to change the frequency, to close the differential time error. But when it comes to orbits and planets, objects too large for us to change their rate, objects which have no EFC input, we have to resort to making artificial, bookkeeping, virtual steps in time instead of gradual changes in physical rate. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Question
Ed, the message about leap pending refers to an impending leap second, in June I think but others may know more... It will happen and the message will go away. From your LH screen, I would say that your signal levels are way too low. I don't know why, perhaps low antenna gain, a badly sited antenna, even indoors maybe? I suspect the t'bolt is working as it should. You don't show your signal strength numbers, but here in Southern California with a well sited -hp- antenna, I see all visible sats with between 47 and 50 signal strength numbers and thus large circles on the map display. Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique Rubidium Standard Questions
Ed, On 04/23/2012 07:54 AM, Ed Palmer wrote: I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. OK. A bit different to some of the rubidiums, but looking around it is not as uncommon as one might think. This technique is used in some of the FEI 5680 and also the later GPS rubidiums. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. What is the OCXO issue? The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. You should see second harmonics regardless, it's an effect of the dip itself. I would check if you can observe the second harmonics on the signal from the detector by some other means. If you seems to lock up but does not see second harmonics, it just could be something in the second harmonics detection which needs some LTC. There are many sources for shifting the frequency, including the power supply (check voltage and clean-ness), the trimming of the C-field, the leakage of helium, resonator tuning, temperature trimming of lamp and resonator may shift amplitude and hence frequency through light pulling. It would be good if you could hook up the modulation sine on X and return signal on Y on a scope, that would give you a clear display of the resonance dip. Oh, and check if you have leakage problems around the integrator cap, that would also shift the frequency. Cheers, Magnus ___ 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] FEC-5680A Won't Lock
I got a EFC-5680A it will not lock. Someone suggested I adjust C217 which worked, but it drifts slightly back and forth some times when started from a cold start it will go out of lock, and may or may not relock. Any suggestions will be appreciated.Thank You - Original Message - From: Magnus Danielson mag...@rubidium.dyndns.org To: time-nuts@febo.com Cc: Sent: Monday, April 23, 2012 4:08:08 PM Subject: Re: [time-nuts] Antique Rubidium Standard Questions Ed, On 04/23/2012 07:54 AM, Ed Palmer wrote: I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. OK. A bit different to some of the rubidiums, but looking around it is not as uncommon as one might think. This technique is used in some of the FEI 5680 and also the later GPS rubidiums. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. What is the OCXO issue? The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. You should see second harmonics regardless, it's an effect of the dip itself. I would check if you can observe the second harmonics on the signal from the detector by some other means. If you seems to lock up but does not see second harmonics, it just could be something in the second harmonics detection which needs some LTC. There are many sources for shifting the frequency, including the power supply (check voltage and clean-ness), the trimming of the C-field, the leakage of helium, resonator tuning, temperature trimming of lamp and resonator may shift amplitude and hence frequency through light pulling. It would be good if you could hook up the modulation sine on X and return signal on Y on a scope, that would give you a clear display of the resonance dip. Oh, and check if you have leakage problems around the integrator cap, that would also shift the frequency. Cheers, Magnus ___ 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.
Re: [time-nuts] FEC-5680A Won't Lock
Hi If you adjust the free running VCXO frequency, you need to monitor just where you set it to. Admittedly this is a bit like saying you need an accurate watch to set your accurate watch. You at least need a counter / standard you can trust to 0.1 ppm. That's usually do-able. If not there are easy ways to get there, so ask. The VCXO ramps up and down while it tries to lock. It should swing a couple hundred hertz low of 10 MHz and at least 10 Hz high. The swing hangs at each end for a while, so it's not to hard to check. I suspect that anything more than 100 Hz high or less than 100 Hz low could be an issue. The main reason is that I've not seen one of these that's outside that range. If the range is OK, then you have a problem elsewhere. If so there are things that can be checked. First thing is to validate the VCXO. Bob On Apr 23, 2012, at 4:13 PM, CORNACCHIA wrote: I got a EFC-5680A it will not lock. Someone suggested I adjust C217 which worked, but it drifts slightly back and forth some times when started from a cold start it will go out of lock, and may or may not relock. Any suggestions will be appreciated.Thank You - Original Message - From: Magnus Danielson mag...@rubidium.dyndns.org To: time-nuts@febo.com Cc: Sent: Monday, April 23, 2012 4:08:08 PM Subject: Re: [time-nuts] Antique Rubidium Standard Questions Ed, On 04/23/2012 07:54 AM, Ed Palmer wrote: I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. OK. A bit different to some of the rubidiums, but looking around it is not as uncommon as one might think. This technique is used in some of the FEI 5680 and also the later GPS rubidiums. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. What is the OCXO issue? The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. You should see second harmonics regardless, it's an effect of the dip itself. I would check if you can observe the second harmonics on the signal from the detector by some other means. If you seems to lock up but does not see second harmonics, it just could be something in the second harmonics detection which needs some LTC. There are many sources for shifting the frequency, including the power supply (check voltage and clean-ness), the trimming of the C-field, the leakage of helium, resonator tuning, temperature trimming of lamp and resonator may shift amplitude and hence frequency through light pulling. It would be good if you could hook up the modulation sine on X and return signal on Y on a scope, that would give you a clear display of the resonance dip. Oh, and check if you have leakage problems around the integrator cap, that would also shift the frequency. Cheers, Magnus ___ 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.
Re: [time-nuts] PRS-10 input and output calibrations
On 04/23/2012 08:16 AM, Poul-Henning Kamp wrote: In message4f947ff0.8070...@rubidium.dyndns.org, Magnus Danielson writes: On 04/22/2012 10:47 PM, b...@lysator.liu.se wrote: Interlocking two oscillators like that might be a really bad idea, as the PLL will have a gain, so risk having a gain loop, especially when the oscillators have the same default parameters being setup. You would clearly want to torque the timeconstant of the second PRS10 in that scenario, but idea is not without merit. It helps a bit. You can build phase margin that way if not the gain margin is on your side. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Question
On 04/23/2012 07:01 PM, Tom Van Baak wrote: I have been using a surplus Thunderbolt for about six months, and it seemed to be working fine. In January 2012, a message came up in yellow, (LEAP PENDING!), I don't know what this means, but since it didn't go away on Feb 28, must not be leap year related. Hi Ed, Right, in this case the LEAP refers to a leap second, not a leap year. When the next leap second occurs this summer, the yellow warning will go away. As you know, leap years are used to keep days and years in sync, where a day is earth rotation (about its axis) and a year is earth revolution (around the sun). Last one was: Feb 29, 2012. Similarly, leap seconds are used to keep seconds and days in sync, where a second is now defined by atomic standards and a day is earth rotation. Next one is: 19:59:60 EDT, Jun 30, 2012. Keeping clocks in sync is a significant part of the timekeeping world. For example, with quartz and GPS it's easy to discipline quartz in order to steer it closer to GPS. This is done by making slight changes in quartz EFC voltage to change the frequency, to close the differential time error. But when it comes to orbits and planets, objects too large for us to change their rate, objects which have no EFC input, we have to resort to making artificial, bookkeeping, virtual steps in time instead of gradual changes in physical rate. I thought someone finally put a cesium on the step motor keeping the ear rotation. But no, free-wheeling like always. There is no order in this universe. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Question
Not yet Marcus- that sort of technology will come right after the ftl drive, but just before we start building a dyson sphere.. On Tue, Apr 24, 2012 at 7:00 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: I thought someone finally put a cesium on the step motor keeping the ear rotation. But no, free-wheeling like always. There is no order in this universe. Cheers, Magnus Ken. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique Rubidium Standard Questions
Hi Magnus, Please note, I goofed when I said that the drift was 30 ppt. It's 30 ppb, i.e. 3e-8. On 4/23/2012 2:08 PM, Magnus Danielson wrote: Ed, On 04/23/2012 07:54 AM, Ed Palmer wrote: I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. OK. A bit different to some of the rubidiums, but looking around it is not as uncommon as one might think. This technique is used in some of the FEI 5680 and also the later GPS rubidiums. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. What is the OCXO issue? Due to drift, the AT crystal is so far off frequency that the EFC can't correct it. There is no frequency adjustment on the oscillator, but there is an adjustment for oven temperature. In order to bring the frequency back into the EFC range, it's running at a temperature below it's turning point. The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. You should see second harmonics regardless, it's an effect of the dip itself. I would check if you can observe the second harmonics on the signal from the detector by some other means. If you seems to lock up but does not see second harmonics, it just could be something in the second harmonics detection which needs some LTC. I had the same thought so I replaced the Rb lamp with an LED that was modulated at the 2nd harmonic frequency. The signal showed up at the 2nd harmonic test point. I changed the modulation to the fundamental frequency and saw approximately the same amplitude at the fundamental test point. Since the signal paths are almost identical (I have the full manual with schematics), I concluded that the signal chain was working and would display the second harmonic if it was present. There are many sources for shifting the frequency, including the power supply (check voltage and clean-ness), the trimming of the C-field, the leakage of helium, resonator tuning, temperature trimming of lamp and resonator may shift amplitude and hence frequency through light pulling. It would be good if you could hook up the modulation sine on X and return signal on Y on a scope, that would give you a clear display of the resonance dip. I just tried that, but had no success. I thought the actual dip was so small that you couldn't see it and that's one of the reasons why the modulation is used? Oh, and check if you have leakage problems around the integrator cap, that would also shift the frequency. I'll check for that, but wouldn't that type of leakage just be corrected by the loop? Thanks, Ed ___ 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] Manuals for HP 570A clock?
Hello, I've got an HP 570A digital clock on the bench for which I am seeking both service and operator manuals. Are there PDF versions available somewhere? Thanks, Dan ___ 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] Time Code Generator
Does anyone have data on a Trak System Model 8390 Time Code Generator? The sticker shows the following: Part Number: 48390-1014-101 Model: 8390-46 I picked this unit from a salvage yard several years ago. I'd like to find a service manual or just schematics? Any takers? Mike Blazer San Antonio, TX ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique Rubidium Standard Questions
I don't understand how it can 'lock' without a 2nd Harmonic Signal. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Monday, April 23, 2012 12:54 AM To: Time-Nuts Subject: [time-nuts] Antique Rubidium Standard Questions I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. FYI, I checked my counter (Racal 1992 referenced to an Efratom FRK-H Rubidium) against my Z3801A and Tbolt. Both measure 10.000 000 000 MHz. so I'm confident that my numbers are good. Thanks, Ed ___ 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.
Re: [time-nuts] Thunderbolt Question
wa6...@comcast.net said: I have been using a surplus Thunderbolt for about six months, and it seemed to be working fine. In January 2012, a message came up in yellow, (LEAP PENDING!), I don't know what this means, but since it didn't go away on Feb 28, must not be leap year related. About a week ago I got a Holdover: xx secs, message. It was a new figure in yellow. Yesterday the Thunderbolt stopped working correctly, there were no satellites found. I tried Lady Heather, and Trimble Studio without success.I finally got the unit back in service with a program called Tboltmon.exe. After it was running for a couple of hours I restarted Lady Heather. This morning I again have Holdover: 50 secs. Does it sound normal, or is this unit headed for the junk box? I didn't see anything that you said that sounds unreasonable. There is a leap second scheduled for the end of June 2012. That info gets distributed via GPS. The TBolt will pass it on to client software. I don't remember the details, but you can find them if you look in the TBolt software data sheet. There is a quirk with NTP. It also has a mechanism for distributing leap-pending info. The catch is that it assumes the leap will be at the end of the current month. (I hacked a Jun/Dec filter into the HP/Z3801A driver because it screwed up the last time we had a leap second. That seemed easier to test and less likely to be buggy than trying to decode the actual time of the next leap second.) I should go check the TBolt code. On the holdover... Holdover just means that you can't see any good-enough satellites. (You only need one for timekeeping.) How good is your antenna location? Were you watching to see if it was going into holdover before? My antenna setup is poor. My TBolt goes into holdover several times a day, more on a bad day, maybe none on a good day. That's great for testing software, not so good for providing a super-clean time or frequency reference. How many times and/or how long it stays in holdover depends upon ??? (I don't know.) It may depend on the phasing of the GPS satellites. It may depend on the weather and/or the amount of water in/on my roof and/or the local trees. (I have a big pine tree to the south/southeast.) -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique Rubidium Standard Questions
Hi Joe, On this unit (not sure about others), the 2nd harmonic is used to unambiguously determine that it is locked. But the 2nd harmonic has no part in the acquisition or maintenance of the lock. That is done by the fundamental. I can tune through resonance and see the standard curve like fig. 5-7 in the HP 5065A manual (see attachment) except mine doesn't quite make it to the full-scale saturation level. I then tune to the resonance point and flip a switch to close the loop. It doesn't turn on the nice green light because that's done by the 2nd harmonic. But it also doesn't drift like an OCXO. Take a look at the second attachment for an ~10 hour data run. The relatively poor performance below 1000 seconds is due to my measurement setup. I was looking for high Tau performance, not low Tau. Ed On 4/23/2012 7:58 PM, J. L. Trantham wrote: I don't understand how it can 'lock' without a 2nd Harmonic Signal. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Monday, April 23, 2012 12:54 AM To: Time-Nuts Subject: [time-nuts] Antique Rubidium Standard Questions I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. FYI, I checked my counter (Racal 1992 referenced to an Efratom FRK-H Rubidium) against my Z3801A and Tbolt. Both measure 10.000 000 000 MHz. so I'm confident that my numbers are good. Thanks, Ed attachment: Fig.5-7.pngattachment: Tracor vs. Tbolt 1pps.png___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique Rubidium Standard Questions
Ed, I am not familiar with the Tracor units, only the 5061A and B as well as the 5065A. These units use the 2nd Harmonic as an integral part of the feedback loop. Without the 2nd Harmonic, is there another way to 'unambiguously determine that it is locked', other than comparing it to a 'known', 'locked' signal? I guess another way to ask the question is do you think you happen to have a particularly good OCXO? Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Monday, April 23, 2012 10:17 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Antique Rubidium Standard Questions Hi Joe, On this unit (not sure about others), the 2nd harmonic is used to unambiguously determine that it is locked. But the 2nd harmonic has no part in the acquisition or maintenance of the lock. That is done by the fundamental. I can tune through resonance and see the standard curve like fig. 5-7 in the HP 5065A manual (see attachment) except mine doesn't quite make it to the full-scale saturation level. I then tune to the resonance point and flip a switch to close the loop. It doesn't turn on the nice green light because that's done by the 2nd harmonic. But it also doesn't drift like an OCXO. Take a look at the second attachment for an ~10 hour data run. The relatively poor performance below 1000 seconds is due to my measurement setup. I was looking for high Tau performance, not low Tau. Ed On 4/23/2012 7:58 PM, J. L. Trantham wrote: I don't understand how it can 'lock' without a 2nd Harmonic Signal. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Monday, April 23, 2012 12:54 AM To: Time-Nuts Subject: [time-nuts] Antique Rubidium Standard Questions I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. FYI, I checked my counter (Racal 1992 referenced to an Efratom FRK-H Rubidium) against my Z3801A and Tbolt. Both measure 10.000 000 000 MHz. so I'm confident that my numbers are good. Thanks, Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique Rubidium Standard Questions
Hi Ed, On 04/24/2012 01:48 AM, Ed Palmer wrote: Hi Magnus, Please note, I goofed when I said that the drift was 30 ppt. It's 30 ppb, i.e. 3e-8. I assumed that. On 4/23/2012 2:08 PM, Magnus Danielson wrote: Ed, On 04/23/2012 07:54 AM, Ed Palmer wrote: I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. OK. A bit different to some of the rubidiums, but looking around it is not as uncommon as one might think. This technique is used in some of the FEI 5680 and also the later GPS rubidiums. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. What is the OCXO issue? Due to drift, the AT crystal is so far off frequency that the EFC can't correct it. There is no frequency adjustment on the oscillator, but there is an adjustment for oven temperature. In order to bring the frequency back into the EFC range, it's running at a temperature below it's turning point. OK. Not ideal but you should still have a useful OCXO. Possibly you could modify it to have a trim-cap. The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. You should see second harmonics regardless, it's an effect of the dip itself. I would check if you can observe the second harmonics on the signal from the detector by some other means. If you seems to lock up but does not see second harmonics, it just could be something in the second harmonics detection which needs some LTC. I had the same thought so I replaced the Rb lamp with an LED that was modulated at the 2nd harmonic frequency. The signal showed up at the 2nd harmonic test point. I changed the modulation to the fundamental frequency and saw approximately the same amplitude at the fundamental test point. Since the signal paths are almost identical (I have the full manual with schematics), I concluded that the signal chain was working and would display the second harmonic if it was present. Good strategy! OK. Signal paths work. There are many sources for shifting the frequency, including the power supply (check voltage and clean-ness), the trimming of the C-field, the leakage of helium, resonator tuning, temperature trimming of lamp and resonator may shift amplitude and hence frequency through light pulling. It would be good if you could hook up the modulation sine on X and return signal on Y on a scope, that would give you a clear display of the resonance dip. I just tried that, but had no success. I thought the actual dip was so small that you couldn't see it and that's one of the reasons why the modulation is used? Yes and no. The modulation is used as it is a convenient way to lock into that feature, but true, it is a weak signal compared to the DC light detection, so AC signals forms a convenient way to allow a cap to block the DC light away, and after some amplification you should have a detectable signal. Oh, and check if you have leakage problems around the integrator cap, that would also shift the frequency. I'll check for that, but wouldn't that type of leakage just be corrected by the loop? Partly, only partly. I would at least have a look there and see if there is a need for cleaning. I think it is a bit strange you don't have your 2nd harmonic. If you managed to have it locked to the wrong hyperfine line, then this would be expected I guess. How does it react to the magnetic field? Linearly or quadratically? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique Rubidium Standard Questions
Hi Joe, On 4/23/2012 9:45 PM, J. L. Trantham wrote: Ed, I am not familiar with the Tracor units, only the 5061A and B as well as the 5065A. These units use the 2nd Harmonic as an integral part of the feedback loop. Without the 2nd Harmonic, is there another way to 'unambiguously determine that it is locked', other than comparing it to a 'known', 'locked' signal? Strictly speaking, the answer is probably 'No'. After all, why would they include the 2nd harmonic circuitry if they didn't need it? There should be 2nd harmonic and I hope to find some somewhere. Remember that this unit is being brought back from the dead as a learning exercise so a few 'minor' issues aren't a show-stopper. The unit has been running for most of the day. I flipped the switch to open the loop. The frequency went from 5 MHz to 5MHz +0.045 Hz while the error meter went from 0 to -25 on a scale of 50. Close the loop and the frequency returned to 5.000 000 000 MHz and the error meter went back to zero. That certainly sounds like locking behaviour to me. I guess another way to ask the question is do you think you happen to have a particularly good OCXO? It's a 40 year old AT-crystal that hasn't had nearly enough recent run time to work the kinks out. I would be astonished to find that it's that good. But I realized that I've never looked at the oscillator by itself so I did a quick test. I measured an aging rate in the range of 0.2 ppm / day. If I cancel out all the aging, the results start to look like the earlier attachment. But not when it's unlocked. Ed Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Monday, April 23, 2012 10:17 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Antique Rubidium Standard Questions Hi Joe, On this unit (not sure about others), the 2nd harmonic is used to unambiguously determine that it is locked. But the 2nd harmonic has no part in the acquisition or maintenance of the lock. That is done by the fundamental. I can tune through resonance and see the standard curve like fig. 5-7 in the HP 5065A manual (see attachment) except mine doesn't quite make it to the full-scale saturation level. I then tune to the resonance point and flip a switch to close the loop. It doesn't turn on the nice green light because that's done by the 2nd harmonic. But it also doesn't drift like an OCXO. Take a look at the second attachment for an ~10 hour data run. The relatively poor performance below 1000 seconds is due to my measurement setup. I was looking for high Tau performance, not low Tau. Ed On 4/23/2012 7:58 PM, J. L. Trantham wrote: I don't understand how it can 'lock' without a 2nd Harmonic Signal. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Monday, April 23, 2012 12:54 AM To: Time-Nuts Subject: [time-nuts] Antique Rubidium Standard Questions I'm playing with a Tracor 304-B Rubidium Standard from 1969. I'm using it as a learning exercise to find out more about the guts of a Rubidium standard and how it works. This thing is a beast! Rack-mount, 3U high, 39 pounds (~18 kilos), 9 plug in circuit boards. The OCXO is an oddball frequency that is multiplied directly to 6.8 GHz. There's no synthesizer in that chain. A synthesizer is used to convert the oddball frequency to a 5 MHz output. It's sort of working. The error signal isn't up to spec, but it's strong enough to give a stable lock although there's no trace of a second harmonic signal. Allan Deviation is in the Xe-12 range from 1K to 10K seconds. The OCXO has a not-yet-resolved issue that is probably degrading the results. The lock frequency suggests that the Rubidium cell has drifted down by ~30ppt over the 40+ years since it was built. Is that reasonable? That's much more drift than the specification states, but I doubt if the spec was intended to be valid for 40 years! Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.html ) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. FYI, I checked my counter (Racal 1992 referenced to an Efratom FRK-H Rubidium) against my Z3801A and Tbolt. Both measure 10.000 000 000 MHz. so I'm confident that my numbers are good. Thanks, Ed ___ 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.
