Re: [time-nuts] OT: Basics of voltage calibration?
search LTZ1000, LM399, and LH0070 at www.linear.com , also get app notes AN42, AN82, and AN86 - and by the way, most big parts houses have quit carrying these references - but they can be ordered direct from Linear Technology. The LTZ1000 is used in HP3458A multimeters and a lot of voltage calibrators from Datron, Fluke, etc. The LM299 and LM399 were used in HP 3457A and HP3456A, and others. more info on LM199/LM399 at national semiconductor, and a few app notes, AN 161 , AN184, finding a good standard cell, is hard to do nowadays. I bought 6 units on ebay, 2 were from folks that had them and they were able to test and furnish data, and the other four were old and the voltage was too low to be stable. Basically if the voltage is not 1.0183 volts and above they are no good. They are finicky and I would read up on them before I would purchase one. NIST had a paper on them that explained the history of them, their construction, and how to handle them and the temperature conversion formulas for the saturated cells. Check out NIST 250-28 Solid State DC Voltage Calibrations, A Sub-PPM Automated 1-10 Volt DC Measuring System by Bruce E. Field, NBS Measurement Services: Standard Cell Calibrations, also by Bruce E. Field, Standard Cells - Their Construction, Maintenance and Characteristics by Walter J. Hamer all at NIST. Look up Kelvin Varley dividers - I don't know if these folks are still in business Julie Labs and ESI. Leeds and Northrup made a few also. HP had some app notes on measurements, look up the 3456A, 3457A, 3458A and it should show some app notes for them. Zicor had AN177, I believe Intersil bought them And Keithley had a free book called Low Level Measurements Handbook - Precision DC Current, Voltage, and Resistance Measurements thats worth a read. If you can find a copy of Current Sources and Voltage References: A Design Reference for Electronics Engineers, by Linden Harrison, its a good read on a lot of semiconductor references in the last 15 years or so - I would see if you can find it in a library somewhere, if you purchase it its about $50-75 on the used market. Brian - KD4FM John Ackermann N8UR wrote: I'm interested in learning some basics about precision voltage calibration (as can be realized by the hobbyist, not Josephson Junction systems!). A Google search hasn't turned up anything like a tutorial. Anyone know of any good app notes or other references on things like standard cells, zener references, precision potentiometers, etc? -- and how to use them? Thanks, John ___ 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] OT: Basics of voltage calibration?
Brian Kirby wrote: search LTZ1000, LM399, and LH0070 at www.linear.com , also get app notes AN42, AN82, and AN86 - and by the way, most big parts houses have quit carrying these references - but they can be ordered direct from Linear Technology. The LTZ1000 is used in HP3458A multimeters and a lot of voltage calibrators from Datron, Fluke, etc. The LM299 and LM399 were used in HP 3457A and HP3456A, and others. more info on LM199/LM399 at national semiconductor, and a few app notes, AN 161 , AN184, finding a good standard cell, is hard to do nowadays. I bought 6 units on ebay, 2 were from folks that had them and they were able to test and furnish data, and the other four were old and the voltage was too low to be stable. Basically if the voltage is not 1.0183 volts and above they are no good. They are finicky and I would read up on them before I would purchase one. NIST had a paper on them that explained the history of them, their construction, and how to handle them and the temperature conversion formulas for the saturated cells. Check out NIST 250-28 Solid State DC Voltage Calibrations, A Sub-PPM Automated 1-10 Volt DC Measuring System by Bruce E. Field, NBS Measurement Services: Standard Cell Calibrations, also by Bruce E. Field, Standard Cells - Their Construction, Maintenance and Characteristics by Walter J. Hamer all at NIST. Look up Kelvin Varley dividers - I don't know if these folks are still in business Julie Labs and ESI. Leeds and Northrup made a few also. One of the best ways to ensure you get a good Weston standard cell is to make your own. However obtaining the Mercury and the Cadmium sulphate may be difficult. The mercury salts are easily produce by electrolysis in a dark enclosure (they are photosensitive). Julie research labs are long gone, however http://www.ohm-labs.com/ make some of the instruments and standards they used to sell. They also claim to have taken over from Leeds and Northrup. Also see: http://www.ietlabs.com/ Fluke still make the 720A KVD. HP had some app notes on measurements, look up the 3456A, 3457A, 3458A and it should show some app notes for them. Zicor had AN177, I believe Intersil bought them And Keithley had a free book called Low Level Measurements Handbook - Precision DC Current, Voltage, and Resistance Measurements thats worth a read. If you can find a copy of Current Sources and Voltage References: A Design Reference for Electronics Engineers, by Linden Harrison, its a good read on a lot of semiconductor references in the last 15 years or so - I would see if you can find it in a library somewhere, if you purchase it its about $50-75 on the used market. Brian - KD4FM John Ackermann N8UR wrote: I'm interested in learning some basics about precision voltage calibration (as can be realized by the hobbyist, not Josephson Junction systems!). A Google search hasn't turned up anything like a tutorial. Anyone know of any good app notes or other references on things like standard cells, zener references, precision potentiometers, etc? -- and how to use them? Thanks, John ___ 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. Bruce ___ 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] OT: Basics of voltage calibration?
Hi Bruce (and others!) -- Thanks to all for the pointers. No, Bruce, I'm not going quite that far. I've just acquired a couple of pieces of voltage gear and don't really know the first thing about the calibration process. I'm really looking to learn the basics (as they were 20 years ago, since that's the vintage of any gear I'll likely be acquiring). Thanks! John Bruce Griffiths said the following on 03/14/2009 10:31 PM: John Did you want a recipe for making your own standard cells? If so you'll also want an oil bath to keep them in. Bruce Bill Beam wrote: John, Check this out: www.gellerlabs.com On 3/14/2009 5:33:45 PM, John Ackermann N8UR (j...@febo.com) wrote: I'm interested in learning some basics about precision voltage calibration (as can be realized by the hobbyist, not Josephson Junction systems!). A Google search hasn't turned up anything like a tutorial. Anyone know of any good app notes or other references on things like standard cells, zener references, precision potentiometers, etc? -- and how to use them? Thanks, John ___ 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. Bill Beam NL7F ___ 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] OT: Basics of voltage calibration?
A good reference is the old Fluke publication Calibration - Philosophy in Practice by Steve Spang. (1975) Be very carefull with standard cells! Never load a cell. Use the cells only with high ohm null detectors. A loaded cell need a long time for regeneration (or come back never to the old value!) I think a good zener reference is a better practical solution for today. Juerg ___ 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] Question about specifications for Quartzlock GPS antenna down-converter
b...@lysator.liu.se skrev: Hi Brooke and Russel, Meinberg does the same thing, but they send a 10MHz - nice choice!! - up the coax to receive an IF of 35.4MHz. http://www.meinberg.de/english/products/gpsant.htm http://www.meinberg.de/download/docs/manuals/english/gpsant.pdf As I have commented before, I suspect that they use the Zarlink chipset, since they have 10 MHz input and 35,4 MHz is an intermediary frequency in that frequency scheme which is available for insert. Using one analog front in the antenna and one analog front in the receiver and feeding them with the same 10 MHz it all works out nicely. I don't know what solution Quartzlock is using. The reduced damping (and hence longer cable runs) is one benefit from down-converting, another could be reduced phase shift problems, but I think for L1 receivers this is not as major issue. 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] OT: Basics of voltage calibration?
Yes, never load a standard cell. It's standard practice to put a jumper across the terminals of a galvanometer for shipping, so the needle (or mirror) doesn't slam around. Some years ago, I got a standard cell from eBay. The terminals had been shorted for shipping. Bill Hawkins -Original Message- From: Jürg Kögel Sent: Sunday, March 15, 2009 7:36 AM A good reference is the old Fluke publication Calibration - Philosophy in Practice by Steve Spang. (1975) Be very carefull with standard cells! Never load a cell. Use the cells only with high ohm null detectors. A loaded cell need a long time for regeneration (or come back never to the old value!) I think a good zener reference is a better practical solution for today. Juerg ___ 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] OT: Basics of voltage calibration?
Hi Bill. I could use that DVM if no one else has spoken for it. Let me know and I'll give you my address off list. My email address is after my signature. Regards. One of the lurkers, Max. K 4 O D S. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com - Original Message - From: John Ackermann N8UR j...@febo.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, March 15, 2009 10:27 AM Subject: Re: [time-nuts] OT: Basics of voltage calibration? Bill Hawkins said the following on 03/14/2009 10:39 PM: I have an extra Fluke DVM around here someplace, if you're interested. Free to a good home for experiments. Hi Bill-- Thanks for the offer on the DVM -- remembering the D is for differential! However, I have an old 893A here that I just powered up for the first time in years. It seems to work (at least, the meter zeros properly) so that gives me something to play with. Don't think I need another one, so maybe someone else will be interested in taking you up on the offer... John ___ 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] Shrinking Atomic Clocks
Time to shrink the atomic clock 14 March 2009 by Anil Ananthaswamy Magazine issue 2699. Subscribe and get 4 free issues. ATOMIC clocks, currently the size of fridges, could shrink to the microscale thanks to a new way of measuring the second. The technique could also see aluminium displace caesium as the standard of time. The world's most accurate atomic clocks are at the National Institute of Standards and Technology (NIST) at Boulder, Colorado. Known as fountain clocks, they send clouds of caesium atoms through a vacuum chamber in a magnetic field. Large atoms like caesium and aluminium have multiple energy levels that are so close together they appear indistinguishable. The magnetic field separates these levels into two hyperfine states. The chamber is also filled with microwaves, which excite the atoms. They then emit light as they drop to the lower hyperfine state. The microwave frequency that maximises this fluorescence is used to define the length of a second, currently the time it takes for 9,192,631,770 cycles of microwave radiation. All this takes place in a large vacuum chamber and so fountain clocks are big devices, about a cubic metre in size. That makes it hard to keep the magnetic field and the device's temperature uniform over the whole area, which can lead to errors of measurement. That's why Andrei Derevianko and Kyle Beloy of the University of Nevada in Reno and colleagues have come up with the idea of trapping the atoms in place using lasers. This means their energy states could be monitored in an area only a few micrometres across, potentially leading to more accurate measurements. This is difficult to get right, though, because the lasers distort an atom's energy levels in a complex way, making it impossible to define a jump that equates to a second. Derevianko's team overcome this problem by finding a laser frequency that alters both hyperfine states by exactly the same amount - a trick that works in aluminium and gallium but not as well in caesium (www.arxiv.org/abs/0808.2821). Then, the energy difference between the levels is the same as if the atoms are in vacuum, says Derevianko. Using this method, the team has calculated the second to be 1506 million cycles of microwaves for aluminium-27 and 2678 million cycles for gallium-69. Although the atoms can be trapped in an area only a few micrometres across, the lasers, and cooling and computing equipment will add to the bulk. Nevertheless, the team say the clocks may be portable and could be used in space-based experiments that require extremely accurate timekeeping, such as those for detecting gravitational waves or for testing Einstein's theories. Tom Heavner, who works on fountain clocks at NIST, describes the proposal as forward-thinking and original. It is a really clever way to meld together the old-style clocks with new laser technology, he says. http://www.newscientist.com/article/mg20126994.900-time-to-shrink-the- atomic-clock.html ___ 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] Shrinking Atomic Clocks
At 05:46 PM 3/15/2009, Thomas A. Frank wrote... 14 March 2009 by Anil Ananthaswamy ATOMIC clocks, currently the size of fridges, A 40 year old HP 5060A is smaller than a small refrigerator. I challenge Anil to tell us what fridge he's thinking of which is the size of an Efratom FRS. (Although you could easily make one using a peltier cooler, that's clearly not what he meant to imply.) The article and headline hype a reduction in size, but there's no detail about that, just that it could be used in space-based experiments, and we already have atomic clocks in space. What magazine was this from? (Anil obviously missed the real significance, which is a potential increase in accuracy, not a decrease in size) ___ 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] FEI 5680a status update
After several weeks of slow evening and hour here and hour there the FEI 5680a is performing on the bench. I was able to get the serial interface to operate for a brief period. The 'S' and 'F' commands worked long enough to change the divisor to produce close to a 10 MHx output, it was 7 Hz low. After pressing the 'up' button several hundred times the unit was very close to 10 MHz. I am not sure why the serial interface stopped responding, I never tried the second documented 'packet' command set. There is also a reset pin on the PIC, it is possible this is not resetting on power up. Now the search for a means to measure the signal error. I tried the oscilloscope method of syncing of a 10 MHz signal produced from a GPS locked oscillator, however it had enough jitter and back and forth to be impractical use. This is where the thought to divide the 10 MHz from the 5680a by 1000 to get a 10kc signal and trigger that to compare with a GPS produced 10kc signal. This produced good results, the FEI unit drifts about 450ns per hour which calculates to be about 1.2**10-10. This measurement is consistent half a dozen periods ranging for 1 to 4 hours and document range of results for using the F software command. I have not measured the effect of a button up or down, however it was significant enough to be obvious that either one up or one down was not correct. There is supposedly a software command set to change the C field. It is documented to have a narrow range; I am not sure of the algorithm to calculate the 'check sum' for the data segment. I would be interested in others experience with these units. Thanks - Dan kb0qil ___ 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] Shrinking Atomic Clocks
On 3/15/09 2:46 PM, Thomas A. Frank ka2...@cox.net wrote: Time to shrink the atomic clock 14 March 2009 by Anil Ananthaswamy Magazine issue 2699. Subscribe and get 4 free issues. ATOMIC clocks, currently the size of fridges, could shrink to the microscale thanks to a new way of measuring the second. The technique could also see aluminium displace caesium as the standard of time. Mind you, there's lots of atomic clocks that are smaller than a refrigerator.. Rb and Cs oscillators are used on spacecraft like the GPS constellation. There's also John Prestage's trapped mercury ion clock that he's developing at JPL. The 1 liter clock, that when it's done will probably displace the traditional Ultra Stable Oscillator (USO), as well as make all sorts of interesting one-way ranging applications from deep space possible. Think of this as something comparable to a Hydrogen maser in performance. Jim ___ 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] Shrinking Atomic Clocks
this appears to be from the website/magazine New Scientist: http://www.newscientist.com/article/mg20126994.900-time-to-shrink-the-atomic-clock.html after reading several of his(Anil's) other articles: http://www.newscientist.com/search?rbauthors=Anil+Ananthaswamy none of them seem to be particularity insightful or well-researched. Especially since the focus (pun intended)of his article seems to me to be the use of lasers to trap atoms and he neglects to mention that the use of lasers is crucial to how fountain clocks operate. On Sun, Mar 15, 2009 at 3:33 PM, Mike S mi...@flatsurface.com wrote: At 05:46 PM 3/15/2009, Thomas A. Frank wrote... 14 March 2009 by Anil Ananthaswamy ATOMIC clocks, currently the size of fridges, A 40 year old HP 5060A is smaller than a small refrigerator. I challenge Anil to tell us what fridge he's thinking of which is the size of an Efratom FRS. (Although you could easily make one using a peltier cooler, that's clearly not what he meant to imply.) The article and headline hype a reduction in size, but there's no detail about that, just that it could be used in space-based experiments, and we already have atomic clocks in space. What magazine was this from? (Anil obviously missed the real significance, which is a potential increase in accuracy, not a decrease in size) ___ 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. -- --Eric _ Eric Garner ___ 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] Shrinking Atomic Clocks
At 07:54 PM 3/15/2009, Eric Garner wrote... this appears to be from the website/magazine New Scientist: Aha. Omni NG (without the credibility of Bob Guccione :-) ). ___ 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] OT: Basics of voltage calibration?
In a message dated 15/03/2009 15:27:52 GMT Standard Time, j...@febo.com writes: However, I have an old 893A here that I just powered up for the first time in years. It seems to work (at least, the meter zeros properly) so that gives me something to play with. --- Hi John and All Some time ago I uploaded the 893A manual to Rapidshare and it can be found at.. _http://rapidshare.com/files/154803854/FLUKE_893A.pdf_ (http://rapidshare.com/files/154803854/FLUKE_893A.pdf) I did try to upload it to Didier's site a few minutes ago but am having access problems again so Didier, if you read this, please feel free to download a copy for your site if you'd like one. regards Nigel GM8PZR ___ 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] FEI 5680a status update
I spent quite a bit of time poking and prodding FE5680's.A while back, I posted a piece about what I found. It covers some important details about programming these units. The part about setting the frequency is at the end of the piece. Dieder has it available on his site: http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:rubidium_oscillators _ Express your personality in color! Preview and select themes for Hotmail®. http://www.windowslive-hotmail.com/LearnMore/personalize.aspx?ocid=TXT_MSGTX_WL_HM_express_032009#colortheme ___ 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] Shrinking Atomic Clocks (Defence of New Scientist)
Well I for one am going to wade in and support this magazine. I think it does an excellent job in presenting week after week the discoveries in science. In fact it is sometimes hard to keep up with them. They reference their sources so you can go in-depth if need be and generally do an excellent job in keep you abreast of this fascinating world. Sure you're going to get the odd article that is written by a non-expert in the field, but at least they are still a scientist and will research it quite well. So maybe, Mr Anil Ananthaswamy got a fact wrong, write to them and they will correct it. But at least the news is out there for discussion and his article has had the desired effect - expansion of knowledge. Jim 2009/3/16 Mike S mi...@flatsurface.com At 07:54 PM 3/15/2009, Eric Garner wrote... this appears to be from the website/magazine New Scientist: Aha. Omni NG (without the credibility of Bob Guccione :-) ). ___ 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] FEI 5680a status update
Mark, Thank you for your work and your reply, I was able to disconnect the output of the DDS board from the 1 second divider, the DDS board produces a clean sine wave. I thank you for your article, I have a couple of follow up questions: 1. Which pot is the C-field? 2. Did you ever set reset on pin 4 of the PIC? 3. Did you succeed in making the RS-232 interface work? 4. If so which interface, the S, F, or the program interface? Thanks Dan kb0qil Mark Sims wrote: I spent quite a bit of time poking and prodding FE5680's.A while back, I posted a piece about what I found. It covers some important details about programming these units. The part about setting the frequency is at the end of the piece. Dieder has it available on his site: http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:rubidium_oscillators _ Express your personality in color! Preview and select themes for Hotmail®. http://www.windowslive-hotmail.com/LearnMore/personalize.aspx?ocid=TXT_MSGTX_WL_HM_express_032009#colortheme ___ 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] FEI 5680a status update
Hello Dan, I think the C-field pot is the one accessible through the hole in the outer cover. If you don't have the cover, it is on one side of the physics package can near the top, center. I never messed with the reset pin. The RS-232 interface works just fine. Most of my units are the version without the DB-9 connector. They have the RS-232 level converter chip and use the S,F interface. If you ever got any S,F data out of your device, that is the interface that it uses. I do have one unit that is probably like yours. It has the DB-9 connector (but I don't think it has the level converter chip). It is set for 15 MHz. I have not used it, so I don't know any details... * _ Windows Live™ Groups: Create an online spot for your favorite groups to meet. http://windowslive.com/online/groups?ocid=TXT_TAGLM_WL_groups_032009 ___ 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.
