[time-nuts] HP 5345A Noise Floor
Hi Bob, The current setup is: Counter locked ( 10 mhz in ) to the Cesium. Same 10 mhz signal from the Cesium feeds both the inputs and counter is running in “phase difference” so time A-B. That means the resolution will be hiher, I guess, since the counter is counting the “difference” between the two Signals, not the whole 10 mhz. I’m a complete dumdum in maths but I’m sure that somebody here can explain in a simple way. Regards, Giorgio. Hi According to page 1-3 in https://bama.edebris.com/download/hp/5345a/5345a_6.pdf <https://bama.edebris.com/download/hp/5345a/5345a_6.pdf> The 5345 is a 2 ns counter. Roughly speaking, that normally gets you around 2x10^-9 at 1 second. That would suggest there is something a bit off in your setup. Bob > On Oct 29, 2020, at 9:26 AM, Giorgio Barinetti barinetti.it<http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>> > wrote: > > Hi All. > > While I’m waiting for a 5370B to come ( find it cheap and beautiful from > France ) I’ve put my old 5345A on a trial, connecting both the > Inputs to the 10 mhz out from an Oscilloquartz 3200 Cesium Oscillator. > > Those are the results. Please advise > > Regards, > Giorgio. > [cid:image001.gif at > 01D6ADF5.5EDF8CF0<http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>] > ___ > time-nuts mailing list -- time-nuts at > lists.febo.com<http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5345A Noise Floor
Hi All. While I’m waiting for a 5370B to come ( find it cheap and beautiful from France ) I’ve put my old 5345A on a trial, connecting both the Inputs to the 10 mhz out from an Oscilloquartz 3200 Cesium Oscillator. Those are the results. Please advise Regards, Giorgio. [cid:image001.gif@01D6ADF5.5EDF8CF0] ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Frequency Counter Choice
Hi Attila, Thanks for the very nice job. I’ll sharpen out my math and try to read it Regards, Giorgio. On Thu, 22 Oct 2020 13:29:07 -0400 Bob kb8tq http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>> wrote: > There is a paper running around behind the IEEE paywall by Collins that > details > one approach to designing multi-stage limiters. There are other ways to do it. > The key is to not go to crazy all in one stage. You can find a modern, more accurate version of Collins result in [1]. While most formulas in there give the noise up to some proportionality factor, all the information to calculate the noise level is in there. The big difference to Collins here is that this result is exact if you use all harmonics up to infinity (which is easy) or can break up with a known error if you don't want to go that far. Collins uses a trapezoid approximation throughout and thus over-estimates the noise contribution of low-gain stages, which are the first stages thus contribute to a relatively large error in the calculation. Attila Kinali [1] "A Physical Sine-to-Square Converter Noise Model" by yours truly, IFCS 2018 http://people.mpi-inf.mpg.de/~adogan/pubs/IFCS2018_comparator_noise.pdf -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Frequency Counter Choice
Hi Bob, Nice explanation. I'll see what I can do to find a 53132. Maybe, in the meantime, if I'll be lucky to find a 5370, I'll play on it. Regarding the mixer based setup, I'm already in progress for setting up a suitable test jig. Please point to some information, if you have it handy. Regards, Giorgio. Hi > On Oct 22, 2020, at 7:50 AM, Giorgio Barinetti barinetti.it<http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>> > wrote: > > Hi, > > As a newbie in the field, I've collected, by chance, some frequency standards. > > Now is the time to measure them, and see how they perform. > > I've inherited a 5371, but something tells me that is not the right > instrument - and maybe is even faulty. > > So, I'm in the need to buy a counter to use togheter with TimeLab. > > Choices are many, but I'll try to avoid the "older" machines lile 5370 or > 5335. The 531xx series seems nice ( money apart ) > But again : which one between the 3 ? 53131, 53132 or 53181 ? 53181 = single channel 400 ps counter 53131 = dual channel 400 ps counter 53132 = dual channel 100 ps counter 5370 (when working) = dual channel 20 ps counter The gotcha is that none of them are good enough to properly measure 1 second ADEV on a good ( but still could be cheap ) OCXO. A mixer based setup is a cheap way to get things done, even with a 5335. The 531xx counters all share a couple of issues: 1) The power supply was made by who knows who and their quality is not the best. Good news is that the power supply out of a (cheap) 53181 will swap over to revive an expensive 53132. 2) They have a fan, it plugs with dust. When that happens it gets hot inside the cabinet. Things (like the power supply) die as a result. 3) They have a VFD display. It's a nice one, but they do wear out. Replacing them is problematic. 4) They have a fancy setup to add digits to a frequency measurement. It can lead you astray. It also tends to go deaf right at 10 MHz. There are app notes out there that explain the details. 5) With *any* counter, a good external reference is the way to go for "Time Nut" grade measurements. None of that is to say they are a bad counter, far from it. I have a number of them and have been using them here and at work for decades. The 532xx counters are the latest and greatest. They are on eBay, but not cheap. Bob > > Can somebody shed some light, and maybe help even to found a baseline for us > beginners ? > > Regards, > IZ2JGB > Giorgio > > My NTP servers: (ntpd on FreeBSD - PPS in via Serial) > > HP/Symmetricom 55300A https://www.ntppool.org/scores/93.41.196.243 > > Efratom Rb/Xc GPSDO https://www.ntppool.org/scores/95.255.136.126 > > > > ___ > time-nuts mailing list -- time-nuts at > lists.febo.com<http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Frequency Counter Choice
Hi, As a newbie in the field, I've collected, by chance, some frequency standards. Now is the time to measure them, and see how they perform. I've inherited a 5371, but something tells me that is not the right instrument - and maybe is even faulty. So, I'm in the need to buy a counter to use togheter with TimeLab. Choices are many, but I'll try to avoid the "older" machines lile 5370 or 5335. The 531xx series seems nice ( money apart ) But again : which one between the 3 ? 53131, 53132 or 53181 ? Can somebody shed some light, and maybe help even to found a baseline for us beginners ? Regards, IZ2JGB Giorgio My NTP servers: (ntpd on FreeBSD - PPS in via Serial) HP/Symmetricom 55300A https://www.ntppool.org/scores/93.41.196.243 Efratom Rb/Xc GPSDO https://www.ntppool.org/scores/95.255.136.126 ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 10811-60164 for sale
Hello, As per subject, i'm selling some quartz oscillator, togheter with the HP 55429B card, salvaged from a telco clocking system. 6pc avail. For inquiries, my email or +393402123322 (english / italian speaking ) Asking 110€ + shipping Thanks ! Regards IZ2JGB Giorgio ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5371A - Basic Howtos
Hi all. I've been given a 5371A that i'll like to use to mesaure Allen Variation and plot results with TimeLab. Can somebody be so kind to give me some hints on how to do that ? (instrument setup etc) Regards, Giorgio. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] EFRATOM MFST rollover way before 6/4 23:59:59
Gents, i realized that my EFRATOM MFST mainframe Rb + OXCO with GPS has rolled over many months before expeted. This summer, in August 21, the display has rolled over to 21/08/1999, and stayed locked then. I wasn't aware, since the unit is located in a rack away from my working desk, but since i've a logging PC Connected to the serial port, saving the logs from the GPS,tonight i've found the rollover event. Did someone notice something similar ? Btw, happy rollover night... Giorgio ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscilloquartz 3210 Cesium Standard Schematics
Good News. I finally decided to leave it running for a few days, after a bit of inspection (changed some caps here and there, removing '77 vingage NiCs batteries, etc). Everything is fine, no alarms, readings are ok. But, still no Ion Current. At least at the meters, both internal and external. Since HV generation is off a sealed module, and not directly, I'll run a measurement on the bare wire going to the tube. https://www.ebay.it/itm/High-Voltage-PS-from-OSCILLOQUARTZ-3102-CESIUM-FREQUENCY-STANDARD-ATOMIC-CLOCK/253730161665?hash=item3b137f0401:g:djEAAMXQ01tRWP7 Voltage is quite High, around 5Kv, that probably means no load from the tube. Any advice ? Ciao, Giorgio. From: Giorgio Barinetti Sent: giovedì 12 luglio 2018 21:49 To: time-nuts@lists.febo.com Subject: Oscilloquartz 3210 Cesium Standard Schematics Hi Tom, Ok and stable were referred to the general behavior of the unit (PSU voltages, current draw). After a 2 h warmup I've run the following test: Frequency has then been measured with the aid of an HP 5345 clocked to a Efratom MFST GPS+Rb and is stable. Phase noise is just around -135 @ 100 hz, output power is 10 dBm. I did not run a full test since I have to be sure that the clock is "safe" in term of leaky capacitors And so on. Leaving a 44 Year instruments running unattended in the lab after 20 years of sleep Does not sound very safe to me :) During the weekend I'll try to keep it running for 48H so I'll see what will happen. In the meantime, thanks for your help! Ciao, Giorgio. > i have been lucky to found a working Oscilloquartz 3210 Cesium ( warehouse of > a telco operator ) in a good shape. Nice find. The OSA 32xx manual that I scanned is at: http://leapsecond.com/museum/osa3200/ That's 33 pages of "Operating and Instruction Manual". If your unit is working within spec, that's sufficient. I'll check if additional manual pages are around here somewhere, in case you need to repair it. > seems ok and stable Words like "ok" or "stable" are vague; try to give numerical measurements for accuracy and stability. That will help determine if your vintage Cs clock is actually working to spec or not. Also log values over time. The ion pump should not have been zero if the unit was sitting in a warehouse for 20 years. But after some hours or days, yes, it could be near zero and this might be a good sign. For an old, surplus, vintage Cs standard, its best to carefully monitor everything immediately after power up and continuing for several hours or days. The trend lines will tell you a great deal about the condition and prognosis of the instrument. /tvb - Original Message - From: "Giorgio Barinetti" http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>> To: http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>> Sent: Wednesday, July 11, 2018 3:17 PM Subject: [time-nuts] Oscilloquartz 3210 Cesium Standard Schematics > Hi Guys, > > i have been lucky to found a working Oscilloquartz 3210 Cesium ( warehouse of > a telco operator ) in a good shape. > > Powers up, seems ok and stable ( capacitors on the unit has 10/1974 date, so > very old unit, serial 83), but the signal > From the preamplifier is a little low and the Ion Pump current is 0. Like the > 3 Kv supply is low ? > > Like to investigate but it will be nice to have a schematic. > > I've found a 2014 message where Tom was willing to scan the remaining part of > the manual, so I'm kindly asking :) > > > Thanks, > Giorgio Barinetti ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscilloquartz 3210 Cesium Standard Schematics
Hi Tom, Ok and stable were referred to the general behavior of the unit (PSU voltages, current draw). After a 2 h warmup I've run the following test: Frequency has then been measured with the aid of an HP 5345 clocked to a Efratom MFST GPS+Rb and is stable. Phase noise is just around -135 @ 100 hz, output power is 10 dBm. I did not run a full test since I have to be sure that the clock is "safe" in term of leaky capacitors And so on. Leaving a 44 Year instruments running unattended in the lab after 20 years of sleep Does not sound very safe to me :) During the weekend I'll try to keep it running for 48H so I'll see what will happen. In the meantime, thanks for your help! Ciao, Giorgio. > i have been lucky to found a working Oscilloquartz 3210 Cesium ( warehouse of > a telco operator ) in a good shape. Nice find. The OSA 32xx manual that I scanned is at: http://leapsecond.com/museum/osa3200/ That's 33 pages of "Operating and Instruction Manual". If your unit is working within spec, that's sufficient. I'll check if additional manual pages are around here somewhere, in case you need to repair it. > seems ok and stable Words like "ok" or "stable" are vague; try to give numerical measurements for accuracy and stability. That will help determine if your vintage Cs clock is actually working to spec or not. Also log values over time. The ion pump should not have been zero if the unit was sitting in a warehouse for 20 years. But after some hours or days, yes, it could be near zero and this might be a good sign. For an old, surplus, vintage Cs standard, its best to carefully monitor everything immediately after power up and continuing for several hours or days. The trend lines will tell you a great deal about the condition and prognosis of the instrument. /tvb - Original Message - From: "Giorgio Barinetti" http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>> To: http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com>> Sent: Wednesday, July 11, 2018 3:17 PM Subject: [time-nuts] Oscilloquartz 3210 Cesium Standard Schematics > Hi Guys, > > i have been lucky to found a working Oscilloquartz 3210 Cesium ( warehouse of > a telco operator ) in a good shape. > > Powers up, seems ok and stable ( capacitors on the unit has 10/1974 date, so > very old unit, serial 83), but the signal > From the preamplifier is a little low and the Ion Pump current is 0. Like the > 3 Kv supply is low ? > > Like to investigate but it will be nice to have a schematic. > > I've found a 2014 message where Tom was willing to scan the remaining part of > the manual, so I'm kindly asking :) > > > Thanks, > Giorgio Barinetti ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscilloquartz 3210 Cesium Standard Schematics
Hi Guys, i have been lucky to found a working Oscilloquartz 3210 Cesium ( warehouse of a telco operator ) in a good shape. Powers up, seems ok and stable ( capacitors on the unit has 10/1974 date, so very old unit, serial 83), but the signal >From the preamplifier is a little low and the Ion Pump current is 0. Like the >3 Kv supply is low ? Like to investigate but it will be nice to have a schematic. I've found a 2014 message where Tom was willing to scan the remaining part of the manual, so I'm kindly asking :) Thanks, Giorgio Barinetti ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
