Re: [volt-nuts] 732A and Prologix received
Charlie, Did my reply to your question along with my lab temperature graph link come through? Just checking as there has been some issues with the posts. I don't like the feature where you don't see your own posts. Don -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Charles Black Sent: Friday, August 29, 2014 3:44 PM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received Hi Don, I'm a bit of trouble sending you this message for some reason. Maybe the third ti me is the charm. Thanks for sharing the graph a few days ago. My 3458A graphs look about the same except I only do voltage so far. I use NPLC 1000 which looks smoother but doesn't really have any additional useful info. I have been meaning to have my TEMP? servoed some time in the near future. My TEMP? runs about 37C at a room temp of 23C. Is your room temp a bit higher? Charlie On 8/29/2014 1:36 PM, Charles Black wrote: ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Hi Don, Your post and link are fine but I need to get some time today to look at it more carefully. I had two posts recently that were blank but since then all seems back to normal. Charlie On 8/31/2014 7:47 AM, Don@True-Cal wrote: Charlie, Did my reply to your question along with my lab temperature graph link come through? Just checking as there has been some issues with the posts. I don't like the feature where you don't see your own posts. Don -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Charles Black Sent: Friday, August 29, 2014 3:44 PM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received Hi Don, I'm a bit of trouble sending you this message for some reason. Maybe the third ti me is the charm. Thanks for sharing the graph a few days ago. My 3458A graphs look about the same except I only do voltage so far. I use NPLC 1000 which looks smoother but doesn't really have any additional useful info. I have been meaning to have my TEMP? servoed some time in the near future. My TEMP? runs about 37C at a room temp of 23C. Is your room temp a bit higher? Charlie On 8/29/2014 1:36 PM, Charles Black wrote: ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Hi Charlie, Yes, in the summer time my lab runs between ~24.5 26.5 C with an occasional excursion beyond either of those limits on extreme days. It is a basement (walkout type) lab with ceramic tile floor which helps account for the muted extremes, and also not having an extreme hot or cold attic overhead. See the link for a lab temperature graph over several days including the last day of the summer voltage run I provided earlier. Since the 3458A accuracy is +/- ~0.5 PPM over typical lab temp extremes, I maintain a database of lab temp, 3458A ref 10.0V readings and 3458A internal temp so I can always refer back if doing a critical voltage transfer. The computer program not only does the graphing but also logs the raw data. While logging, I use lower (100 or 200) NPLC settings so my raw data resolution provides more detail for other types of post processing. But even when doing a voltage transfer, I never see an advantage, and don't use an NPLC setting over 300 (5-min). I would love to maintain the standard 23C lab temp but in the summer months here in the Midwest US, that gets too expensive. Winter temperatures are centered fairly close to 23C. The lab temperature graph link shows four PRT sensors, one is simply in open air thus subject to the same air currents as all instruments while the remaining three are in two different temperature dry-wells (powered off of course) that contribute considerable thermal mass. https://www.dropbox.com/s/r5vl3v0k3s9t8n1/Lab%20Temp%208-22%20to%208-30%202014.pdf?dl=0 Don -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Charles Black Sent: Friday, August 29, 2014 3:44 PM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received Hi Don, I'm a bit of trouble sending you this message for some reason. Maybe the third ti me is the charm. Thanks for sharing the graph a few days ago. My 3458A graphs look about the same except I only do voltage so far. I use NPLC 1000 which looks smoother but doesn't really have any additional useful info. I have been meaning to have my TEMP? servoed some time in the near future. My TEMP? runs about 37C at a room temp of 23C. Is your room temp a bit higher? Charlie On 8/29/2014 1:36 PM, Charles Black wrote: ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Woops sorry, meant to type don't use an NPLC setting over 300 (5-sec) not 5-min. Actually, with AZERO=on, I guess that's 5 seconds of integration over 10 seconds or time. Don -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Charles Black Sent: Friday, August 29, 2014 3:44 PM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received Hi Don, I'm a bit of trouble sending you this message for some reason. Maybe the third ti me is the charm. Thanks for sharing the graph a few days ago. My 3458A graphs look about the same except I only do voltage so far. I use NPLC 1000 which looks smoother but doesn't really have any additional useful info. I have been meaning to have my TEMP? servoed some time in the near future. My TEMP? runs about 37C at a room temp of 23C. Is your room temp a bit higher? Charlie On 8/29/2014 1:36 PM, Charles Black wrote: ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
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Re: [volt-nuts] 732A and Prologix received
Hi Don, I'm a bit of trouble sending you this message for some reason. Maybe the third ti me is the charm. Thanks for sharing the graph a few days ago. My 3458A graphs look about the same except I only do voltage so far. I use NPLC 1000 which looks smoother but doesn't really have any additional useful info. I have been meaning to have my TEMP? servoed some time in the near future. My TEMP? runs about 37C at a room temp of 23C. Is your room temp a bit higher? Charlie On 8/29/2014 1:36 PM, Charles Black wrote: ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
In message CAPmQ2J_Fa1Oo6m=doj-u05f4dqhgpakdvjpsvggyrofe6tj...@mail.gmail.com , Stan Katz writes: *real* metrology purists keep their instruments in a pre helium atmosphere to improve cooling, prevent corrosion and stop people from breathning on things :-) -- 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. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
I do fully agree with you. this has become, to a big extent, an academic debate. it may be relavant if the resolution needs to be in the nv-range, such as working with josephson-elements. I guess nobody in this group here is. to your question, yes, the 34420a and the 2182 nanovolt meters use pure copper contacts, and from time to time they should be cleaned with deoxit. I have not seen any issue with these connectors. would I use unplated (non-gold-surface) copper connectors if I had a choice. never. did i ever have an emf problem with my gold plated copper spades in use together with the 34420a and 3458a. no. so for me at least the answer is simple. Gesendet: Mittwoch, 27. August 2014 um 23:50 Uhr Von: Stan Katz stan.katz...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received As a non-scholar in metrology, I tend to want to simplify the results of an academic debate to make the results of the debate useful to me. One thing is clear from my web search, copper alloyed with Tellurium, or Beryllium, still oxidizes, only at a slower rate. It appears that a big disadvantage of Beryllium oxide is its very hard, a useful industrial characteristic. Not a nice property in the metrology lab. Here goes: For the purists with lab grade metallurgical abrasives, polishing equipment, and oxide removal chemistry, only, copper, whether alloyed with Beryllium or Tellurium is all they want to see in their lead terminations, and they will try to procure only instruments with copper/copper alloy terminals. These purists will clean/deoxidize all connections in a controlled atmosphere, and dry them in completely dry nitrogen, or other inert gas. The connections will then be used immediately during the measurement and the purists will have assured themselves that all instrument to lead connections are tight enough to be oxygen free. Can anyone mention any precision metrology instrumentation in current production with pure copper, or copper alloy connectors? I have a 38 year old Hp 740b, and yep, it's got Gold flashed connectors. This Gold flashing seems to be a tradition. The practical metrologist, will accept the fact that precision metrology instruments are meant to last many years, and the terminals supplied with these instruments must provide a stable thermal emf profile over time. Thus, they accept instruments that come with gold plated terminals. The Gold may need to be cleansed of debris, and degreased from time-to-time, but the procedure is much simpler, and not as time consuming as oxide removal. The leads to these instruments are meant to be used day in, and day out, as well. Therefore, the leads also terminate in some form of gold plated connector. The practical metrologist is fastidious in controlling temperature, and air movement in the lab, to minimize thermal unbalance in his/her lash up. Is this a foolish simplification of the thermals debate, or can I feel vindicated using my homemade, gold plated lead terminations with my old 740b, and 731b? On Wed, Aug 27, 2014 at 3:45 PM, M K m1k...@hotmail.com wrote: On 26/08/2014 16:05, Mike S wrote: After some more research, I think I've answered some of my own questions - Tellurium copper is used for binding posts, not because it has any special thermal or EMF mojo, but because it machines much better than pure copper. And, I suppose, because it sounds like it's extra special. The Seebeck coefficients (uV/C, relative to Cu) of some relevant materials: Cu 0.0 Ag .2 Au .5 Yellow brass 1.5 Phosphor bronze 2.0 63/37 solder 3.0 Sn 3.1 Stainless steel 3.1 Beryllium copper 5.0 Fe -12.3 Ni 22.3 Te -49.25 Based on the extreme Seebeck coefficient of pure tellurium vs. copper, I'd expect that there might be some coefficient between Cu and CuTe (0.5% Te), but I could find no reference. The relatively large number for CuBe is interesting, since that's a common material for banana plug springs, where one might expect the greatest temperature differential to occur in such a connection (between the thermal masses of the binding post/jack and the bulk of the banana plug). Heat has to flow a considerable distance through the springs, very much more than when it flows through a surface plating. The Pomona (Fluke) EM5295-48-0# uses CuBe (gold plated) for the spring contacts. It seems there might be an improvement to be had by using the older style pin plugs, where a solid pin was partially sliced into 4 sections which were then spread apart a bit to create tension. That could eliminate relatively large thermocouples at a thermal gradient, and might also be expected to have less thermal resistance, allowing the connection to settle quicker. But maybe not - I'm still not clear on how plated conductors behave in this situation. For a high impedance voltage measurement
Re: [volt-nuts] 732A and Prologix received
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Re: [volt-nuts] 732A and Prologix received
I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt
Re: [volt-nuts] 732A and Prologix received
I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long. Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com wrote: I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high
Re: [volt-nuts] 732A and Prologix received
well, what you do is to measure the stability of the 3458a. 1ppm drift though sounds much as overall short term average variation if your temperature is stable and your 3458a is always on. probably the temp is not stable, and that is what you see, amongst potentially some other smaller drifts like emf. before every cycle you should do an acal dcv, if you still see 10uv +/- drifts that then seems too much. (one thing I need to add is that one of my 3458a, not yet modified to have lower reference temperature, has drifts when switched on and off. that is not so much the case with modified reference. but my assumption re the above is that your meter is always on, as I said) 732a references et al do have small short term drifts, you can determine them with a josephson element (these guys told me), but the 732a is certainly very stable short term compared to a 3458a. my 732a e.g. has a drift of 0.2ppm per year. Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long. Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com wrote: I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables
Re: [volt-nuts] 732A and Prologix received
Randy: Something I had never tried to measure. As I have found out in the past there is a lot of overhead going on in the meter during and after a measurement. In thinking about this I turned OFF the autozero AZERO and the time for each SMPL was cut in half to around the estimated 16.66 seconds for 1000 PLC. So it becomes obvious that the meter makes an autozero measurement for 1000 PLC and then the actual measurement for 1000 PLC which explains the 33 seconds. Makes sense. This is probably why the AZERO menu gives you ON, OFF and ONCE. For short measurement sequences you just autozero ONCE at the start. Thanks for the observation, this helps me. Everyday I learn something new. Bill Thanks for the information - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Tuesday, August 26, 2014 2:16 PM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I measured the time between SMPL symbols with NPLC set to 1000 and it is approximately 33 seconds. It takes an hour to complete 100 readings. Randy On Mon, Aug 25, 2014 at 10:01 PM, Bill Gold wpgold3...@att.net wrote: Not that I know of. Just wait and when you don't see a SMPL on the display it is done. But then with 1000 PLC that is around 16.66 seconds per reading times 100 readings is somewhere around 28 minutes and there is probably some overhead time so around 30 minutes. Not from the front panel at any rate. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Monday, August 25, 2014 9:23 PM Subject: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I
Re: [volt-nuts] 732A and Prologix received
I have included a link to an ~30-hour measurement run that I consistently do that should give you some idea of expected measurement drift over time. Virtually all of the measurement drift is due to the 3458A internal temperature differences around the 7V reference caused by ambient temperature change. The drift associated with the 732A is probably about 2-magnitudes less at this ambient temp drift. In my situation, the inferred ambient temperature is cycling with the home air-conditioning. Note the initial calibration temperatures as well as the ACal temperatures and where the 3458A is measuring exactly 10V relative to those temperatures. My primary 732A has been powered without loss for 4 years and 5 years before that. The 3458A is Agilent (Loveland) Cal'ed yearly and is powered 24-7-365 except for the occasional mains power loss. The graphical measurements is using a homegrown Agilent VEE program. It is very helpful if not essential to get an HPIB interface setup so you can do long term graphical analysis. The other link was done in winter time when the lab a few degrees cooler. https://www.dropbox.com/s/8je482i3r0belqn/732A%20gold%20%26%203458A%20gold%2032-hour%20Ref%20Test%208-21-2014.pdf?dl=0 https://www.dropbox.com/s/xv3l9py7tx6hyh7/HP%20732A%20gold%20%26%203458A%20gold%207-day%2010.0v%20Ref%20Test.pdf?dl=0 I hope these Dropbox links work internationally - I'm new to using this sharing method. Don Johnson -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of acb...@gmx.de Sent: Wednesday, August 27, 2014 8:42 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received well, what you do is to measure the stability of the 3458a. 1ppm drift though sounds much as overall short term average variation if your temperature is stable and your 3458a is always on. probably the temp is not stable, and that is what you see, amongst potentially some other smaller drifts like emf. before every cycle you should do an acal dcv, if you still see 10uv +/- drifts that then seems too much. (one thing I need to add is that one of my 3458a, not yet modified to have lower reference temperature, has drifts when switched on and off. that is not so much the case with modified reference. but my assumption re the above is that your meter is always on, as I said) 732a references et al do have small short term drifts, you can determine them with a josephson element (these guys told me), but the 732a is certainly very stable short term compared to a 3458a. my 732a e.g. has a drift of 0.2ppm per year. Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long. Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com wrote: I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY
Re: [volt-nuts] 732A and Prologix received
The HP3458A and the Fluke 732A are on continuously and I do an ACAL at least every few hours, or when the room temperature changes by more than 1 degree C. The total range of measurements is 10uV so the drift is +/-5uV, or 0.5 ppm. The room temperature is not particularly stable and varies over a 3C range. The internal temp of the 3458 varies from 38.1 to 40.3 degrees C over the set of measurements. The 732A thermistor resistance measures from 3.6677 Kohms to 3.6686 Kohms. I am using copper wires between the 3458A and the 752A to minimize thermals. At the moment I have no way to tell which unit is drifting the most. Randy On Wed, Aug 27, 2014 at 6:41 AM, acb...@gmx.de wrote: well, what you do is to measure the stability of the 3458a. 1ppm drift though sounds much as overall short term average variation if your temperature is stable and your 3458a is always on. probably the temp is not stable, and that is what you see, amongst potentially some other smaller drifts like emf. before every cycle you should do an acal dcv, if you still see 10uv +/- drifts that then seems too much. (one thing I need to add is that one of my 3458a, not yet modified to have lower reference temperature, has drifts when switched on and off. that is not so much the case with modified reference. but my assumption re the above is that your meter is always on, as I said) 732a references et al do have small short term drifts, you can determine them with a josephson element (these guys told me), but the 732a is certainly very stable short term compared to a 3458a. my 732a e.g. has a drift of 0.2ppm per year. Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long. Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com wrote: I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad
Re: [volt-nuts] 732A and Prologix received
Don, If I am reading your charts correctly, it looks like your system is cycling over an 7 uV range over several days in summer, similar to what I am seeing. I don't have air conditioning (Northern California) so I do get some pretty good temperature variations from day to night, but less inside the house. I need to figure out how to share files in Dropbox since I don't have my own web site. Good idea. thanks, Randy On Wed, Aug 27, 2014 at 7:40 AM, Don@True-Cal truecalservi...@gmail.com wrote: I have included a link to an ~30-hour measurement run that I consistently do that should give you some idea of expected measurement drift over time. Virtually all of the measurement drift is due to the 3458A internal temperature differences around the 7V reference caused by ambient temperature change. The drift associated with the 732A is probably about 2-magnitudes less at this ambient temp drift. In my situation, the inferred ambient temperature is cycling with the home air-conditioning. Note the initial calibration temperatures as well as the ACal temperatures and where the 3458A is measuring exactly 10V relative to those temperatures. My primary 732A has been powered without loss for 4 years and 5 years before that. The 3458A is Agilent (Loveland) Cal'ed yearly and is powered 24-7-365 except for the occasional mains power loss. The graphical measurements is using a homegrown Agilent VEE program. It is very helpful if not essential to get an HPIB interface setup so you can do long term graphical analysis. The other link was done in winter time when the lab a few degrees cooler. https://www.dropbox.com/s/8je482i3r0belqn/732A%20gold%20%26%203458A%20gold%2032-hour%20Ref%20Test%208-21-2014.pdf?dl=0 https://www.dropbox.com/s/xv3l9py7tx6hyh7/HP%20732A%20gold%20%26%203458A%20gold%207-day%2010.0v%20Ref%20Test.pdf?dl=0 I hope these Dropbox links work internationally - I'm new to using this sharing method. Don Johnson -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of acb...@gmx.de Sent: Wednesday, August 27, 2014 8:42 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received well, what you do is to measure the stability of the 3458a. 1ppm drift though sounds much as overall short term average variation if your temperature is stable and your 3458a is always on. probably the temp is not stable, and that is what you see, amongst potentially some other smaller drifts like emf. before every cycle you should do an acal dcv, if you still see 10uv +/- drifts that then seems too much. (one thing I need to add is that one of my 3458a, not yet modified to have lower reference temperature, has drifts when switched on and off. that is not so much the case with modified reference. but my assumption re the above is that your meter is always on, as I said) 732a references et al do have small short term drifts, you can determine them with a josephson element (these guys told me), but the 732a is certainly very stable short term compared to a 3458a. my 732a e.g. has a drift of 0.2ppm per year. Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long. Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com wrote: I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using
Re: [volt-nuts] 732A and Prologix received
Randy, Sorry for the two graphs being at different scales so just be sure to readjust your reference. I like to think in PPM terms so the first graph is +/- 5 PPM for the whole gray plot area while the second is +/- 1 PPM. The most extreme outliers on the first graph is +0.3 to -0.5 PPM so that would be 10.0 uV. The winter graph is +0.1 to -0.9 PPM and would be 10.0 uV. All referenced around 10.0 V. Don -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Randy Evans Sent: Wednesday, August 27, 2014 10:50 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received Don, If I am reading your charts correctly, it looks like your system is cycling over an 7 uV range over several days in summer, similar to what I am seeing. I don't have air conditioning (Northern California) so I do get some pretty good temperature variations from day to night, but less inside the house. I need to figure out how to share files in Dropbox since I don't have my own web site. Good idea. thanks, Randy On Wed, Aug 27, 2014 at 7:40 AM, Don@True-Cal truecalservi...@gmail.com wrote: I have included a link to an ~30-hour measurement run that I consistently do that should give you some idea of expected measurement drift over time. Virtually all of the measurement drift is due to the 3458A internal temperature differences around the 7V reference caused by ambient temperature change. The drift associated with the 732A is probably about 2-magnitudes less at this ambient temp drift. In my situation, the inferred ambient temperature is cycling with the home air-conditioning. Note the initial calibration temperatures as well as the ACal temperatures and where the 3458A is measuring exactly 10V relative to those temperatures. My primary 732A has been powered without loss for 4 years and 5 years before that. The 3458A is Agilent (Loveland) Cal'ed yearly and is powered 24-7-365 except for the occasional mains power loss. The graphical measurements is using a homegrown Agilent VEE program. It is very helpful if not essential to get an HPIB interface setup so you can do long term graphical analysis. The other link was done in winter time when the lab a few degrees cooler. https://www.dropbox.com/s/8je482i3r0belqn/732A%20gold%20%26%203458A%20 gold%2032-hour%20Ref%20Test%208-21-2014.pdf?dl=0 https://www.dropbox.com/s/xv3l9py7tx6hyh7/HP%20732A%20gold%20%26%20345 8A%20gold%207-day%2010.0v%20Ref%20Test.pdf?dl=0 I hope these Dropbox links work internationally - I'm new to using this sharing method. Don Johnson -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of acb...@gmx.de Sent: Wednesday, August 27, 2014 8:42 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received well, what you do is to measure the stability of the 3458a. 1ppm drift though sounds much as overall short term average variation if your temperature is stable and your 3458a is always on. probably the temp is not stable, and that is what you see, amongst potentially some other smaller drifts like emf. before every cycle you should do an acal dcv, if you still see 10uv +/- drifts that then seems too much. (one thing I need to add is that one of my 3458a, not yet modified to have lower reference temperature, has drifts when switched on and off. that is not so much the case with modified reference. but my assumption re the above is that your meter is always on, as I said) 732a references et al do have small short term drifts, you can determine them with a josephson element (these guys told me), but the 732a is certainly very stable short term compared to a 3458a. my 732a e.g. has a drift of 0.2ppm per year. Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long. Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com wrote: I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable
Re: [volt-nuts] 732A and Prologix received
hi randy, the specified drift of the 3458a over your 38.1 to 40.3 (about 1k) is 1ppm +/- allone in the 10v range. thats 10uv. in other ranges its worse. unless your 732a is very bad (very unlikely), you measure mostly the 3458a temp. drift. 1000nplc and 100 readings average do not make sense in that context. if your goal is to be at 0.01ppm additional gain error by using the nplc1000, you need to be sure your temp related drift is even below that. 0.01ppm of temp drift equates 20mk temp stability! you see that all this does not make much sense. adrian Gesendet: Mittwoch, 27. August 2014 um 15:37 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received The HP3458A and the Fluke 732A are on continuously and I do an ACAL at least every few hours, or when the room temperature changes by more than 1 degree C. The total range of measurements is 10uV so the drift is +/-5uV, or 0.5 ppm. The room temperature is not particularly stable and varies over a 3C range. The internal temp of the 3458 varies from 38.1 to 40.3 degrees C over the set of measurements. The 732A thermistor resistance measures from 3.6677 Kohms to 3.6686 Kohms. I am using copper wires between the 3458A and the 752A to minimize thermals. At the moment I have no way to tell which unit is drifting the most. Randy On Wed, Aug 27, 2014 at 6:41 AM, acb...@gmx.de wrote: well, what you do is to measure the stability of the 3458a. 1ppm drift though sounds much as overall short term average variation if your temperature is stable and your 3458a is always on. probably the temp is not stable, and that is what you see, amongst potentially some other smaller drifts like emf. before every cycle you should do an acal dcv, if you still see 10uv +/- drifts that then seems too much. (one thing I need to add is that one of my 3458a, not yet modified to have lower reference temperature, has drifts when switched on and off. that is not so much the case with modified reference. but my assumption re the above is that your meter is always on, as I said) 732a references et al do have small short term drifts, you can determine them with a josephson element (these guys told me), but the 732a is certainly very stable short term compared to a 3458a. my 732a e.g. has a drift of 0.2ppm per year. Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long. Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com wrote: I am doing multiple 100 measurements simply to characterize the stability of the 3458A and 732A units I just bought. After about 10 measurement sets over 2 days I am seeing a variance of about .5 uV for the 10V output, or 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does that sound reasonable/ Randy On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote: hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40
Re: [volt-nuts] 732A and Prologix received
On 26/08/2014 16:05, Mike S wrote: After some more research, I think I've answered some of my own questions - Tellurium copper is used for binding posts, not because it has any special thermal or EMF mojo, but because it machines much better than pure copper. And, I suppose, because it sounds like it's extra special. The Seebeck coefficients (uV/C, relative to Cu) of some relevant materials: Cu 0.0 Ag .2 Au .5 Yellow brass 1.5 Phosphor bronze 2.0 63/37 solder 3.0 Sn 3.1 Stainless steel 3.1 Beryllium copper 5.0 Fe -12.3 Ni 22.3 Te -49.25 Based on the extreme Seebeck coefficient of pure tellurium vs. copper, I'd expect that there might be some coefficient between Cu and CuTe (0.5% Te), but I could find no reference. The relatively large number for CuBe is interesting, since that's a common material for banana plug springs, where one might expect the greatest temperature differential to occur in such a connection (between the thermal masses of the binding post/jack and the bulk of the banana plug). Heat has to flow a considerable distance through the springs, very much more than when it flows through a surface plating. The Pomona (Fluke) EM5295-48-0# uses CuBe (gold plated) for the spring contacts. It seems there might be an improvement to be had by using the older style pin plugs, where a solid pin was partially sliced into 4 sections which were then spread apart a bit to create tension. That could eliminate relatively large thermocouples at a thermal gradient, and might also be expected to have less thermal resistance, allowing the connection to settle quicker. But maybe not - I'm still not clear on how plated conductors behave in this situation. For a high impedance voltage measurement where almost no current flows, the gold plating may carry the signal, so there is no real thermocouple (or more correctly, it's entirely contained within the connector). But if that's the case, why fool around with special copper connectors when common brass ones would be easier/cheaper? For current or resistance, the signal would also flow through the base metal, so does this have an effect (especially for tinned copper test leads, where there may be a larger temperature difference between the ends??? Nickle is avoided as a contact material largely because it is subject to fretting corrosion. Tests done by AMP (http://www.te.com/documentation/whitepapers/pdf/p154-74.pdf) show that a Ni to Ni contact can increase from 8 mOhm to 5 Ohms (sic!) in a short time due to this, while Ag and Au plated contacts exhibit negligible changes. Cu (with Be for better machining) seems to be used as the base material for jacks/plugs to get thermal EMF cancellation to the wiring on both sides (i.e. use copper everywhere except where there is a minimal thermal gradient, like platings). Beryllium copper is a springy material, Tellurium is the material added to aid machining without adding too much seebeck coefficient. I remember someone on this list a long time ago saying that NPL used van damme star quad cable and bought bulk quantities of spade lugs that they strip all the coating off before crimping and clean before each use. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
As a non-scholar in metrology, I tend to want to simplify the results of an academic debate to make the results of the debate useful to me. One thing is clear from my web search, copper alloyed with Tellurium, or Beryllium, still oxidizes, only at a slower rate. It appears that a big disadvantage of Beryllium oxide is its very hard, a useful industrial characteristic. Not a nice property in the metrology lab. Here goes: For the purists with lab grade metallurgical abrasives, polishing equipment, and oxide removal chemistry, only, copper, whether alloyed with Beryllium or Tellurium is all they want to see in their lead terminations, and they will try to procure only instruments with copper/copper alloy terminals. These purists will clean/deoxidize all connections in a controlled atmosphere, and dry them in completely dry nitrogen, or other inert gas. The connections will then be used immediately during the measurement and the purists will have assured themselves that all instrument to lead connections are tight enough to be oxygen free. Can anyone mention any precision metrology instrumentation in current production with pure copper, or copper alloy connectors? I have a 38 year old Hp 740b, and yep, it's got Gold flashed connectors. This Gold flashing seems to be a tradition. The practical metrologist, will accept the fact that precision metrology instruments are meant to last many years, and the terminals supplied with these instruments must provide a stable thermal emf profile over time. Thus, they accept instruments that come with gold plated terminals. The Gold may need to be cleansed of debris, and degreased from time-to-time, but the procedure is much simpler, and not as time consuming as oxide removal. The leads to these instruments are meant to be used day in, and day out, as well. Therefore, the leads also terminate in some form of gold plated connector. The practical metrologist is fastidious in controlling temperature, and air movement in the lab, to minimize thermal unbalance in his/her lash up. Is this a foolish simplification of the thermals debate, or can I feel vindicated using my homemade, gold plated lead terminations with my old 740b, and 731b? On Wed, Aug 27, 2014 at 3:45 PM, M K m1k...@hotmail.com wrote: On 26/08/2014 16:05, Mike S wrote: After some more research, I think I've answered some of my own questions - Tellurium copper is used for binding posts, not because it has any special thermal or EMF mojo, but because it machines much better than pure copper. And, I suppose, because it sounds like it's extra special. The Seebeck coefficients (uV/C, relative to Cu) of some relevant materials: Cu 0.0 Ag .2 Au .5 Yellow brass 1.5 Phosphor bronze 2.0 63/37 solder 3.0 Sn 3.1 Stainless steel 3.1 Beryllium copper 5.0 Fe -12.3 Ni 22.3 Te -49.25 Based on the extreme Seebeck coefficient of pure tellurium vs. copper, I'd expect that there might be some coefficient between Cu and CuTe (0.5% Te), but I could find no reference. The relatively large number for CuBe is interesting, since that's a common material for banana plug springs, where one might expect the greatest temperature differential to occur in such a connection (between the thermal masses of the binding post/jack and the bulk of the banana plug). Heat has to flow a considerable distance through the springs, very much more than when it flows through a surface plating. The Pomona (Fluke) EM5295-48-0# uses CuBe (gold plated) for the spring contacts. It seems there might be an improvement to be had by using the older style pin plugs, where a solid pin was partially sliced into 4 sections which were then spread apart a bit to create tension. That could eliminate relatively large thermocouples at a thermal gradient, and might also be expected to have less thermal resistance, allowing the connection to settle quicker. But maybe not - I'm still not clear on how plated conductors behave in this situation. For a high impedance voltage measurement where almost no current flows, the gold plating may carry the signal, so there is no real thermocouple (or more correctly, it's entirely contained within the connector). But if that's the case, why fool around with special copper connectors when common brass ones would be easier/cheaper? For current or resistance, the signal would also flow through the base metal, so does this have an effect (especially for tinned copper test leads, where there may be a larger temperature difference between the ends??? Nickle is avoided as a contact material largely because it is subject to fretting corrosion. Tests done by AMP (http://www.te.com/ documentation/whitepapers/pdf/p154-74.pdf) show that a Ni to Ni contact can increase from 8 mOhm to 5 Ohms (sic!) in a short time due to this, while Ag and Au plated contacts exhibit negligible changes. Cu (with Be for better machining) seems to be used as the base material for jacks/plugs to get thermal EMF
Re: [volt-nuts] 732A and Prologix received
Bill, I measured the time between SMPL symbols with NPLC set to 1000 and it is approximately 33 seconds. It takes an hour to complete 100 readings. Randy On Mon, Aug 25, 2014 at 10:01 PM, Bill Gold wpgold3...@att.net wrote: Not that I know of. Just wait and when you don't see a SMPL on the display it is done. But then with 1000 PLC that is around 16.66 seconds per reading times 100 readings is somewhere around 28 minutes and there is probably some overhead time so around 30 minutes. Not from the front panel at any rate. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Monday, August 25, 2014 9:23 PM Subject: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low
Re: [volt-nuts] 732A and Prologix received
hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect
Re: [volt-nuts] 732A and Prologix received
I have used the pomona spades, mainly to interface the low emf pomona banana cables to binding posts. I have stopped this, reasons being, they are large and worse, that the pomona spring loaded insulation tube that covers the banana plug conductor uses such a strong spring that slowly the plug works its way out of the spade. this btw also happend to me when I used the pomona low emf binding posts together with the pomona low emf banana cables. overall I m not happy with these. so, due to lack of options, I changed to self-made twisted shielded pair of high grade teflon/kapton silver plated copper cable with gold plated copper spades (crimped). I use them not only with the 3458a but also with nanovolt meters. these have higher resolution and accuracy in low level measurements than the 3458a. emf voltages were never an issue with these cables if properly used. I have posted some results doing 34420a stabilty measurements on the pmel forum, and the results are convincing (purpose was actually not to test the cables but the stability of the 34420a, but the emf issue is a part of this of course. we use the 34420a to do low voltage precision measurements on thermal converters where the full scale signal sometimes is 1mV). that btw also relates to don's statements below, I do not concurr with his comments about copper telurium as cable and spade material and so on. this material, as stated here many times, is used because it is machinable, for copper spades one would not use it. the 34420a factory cable uses copper cable and copper spades, not telurium-copper. if there was a problem, it would be worse with the 34420a than with the 3458a because of its low level ranges. and again, I have not seen any problems in a chain of (output to input): 1.copper-tellurium post from e.g. 8 digit calibrator 2.crimped copper spade, gold plated 3.silver plated tsp copper cable 4a.crimped copper spade to copper-tellurium post or 4b.soldered copper connector(34420) my consistent results over more than a year using them. Gesendet: Montag, 25. August 2014 um 06:33 Uhr Von: Orin Eman orin.e...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received On Sun, Aug 24, 2014 at 1:46 PM, Don@True-Cal truecalservi...@gmail.com wrote: Randy all, You have correctly concluded that some (maybe not all) of your measurement problem is thermal EMF being added or subtracted in series within your measurement interconnect. This thermal EMF is generated at the junction of dissimilar metals when accompanied with thermal gradients between the test lead and device terminals. You have to eliminate both the dissimilarity of the metal junctions as well as minimize the thermal differences. The terminals of the 3458A as well as the 732A are Beryllium Copper so you want to use the same test lead terminals. Forget the typical Tin plated lugs or even Gold plated as both are not Beryllium Copper and constitute dissimilar metals. The best solution (as usually the most expensive) is to use a set of Fluke 5440A-7005 (48) cables. I also have just as good results using the much more flexible Pomona 11174A (lugs end always stay connected to the 732A) or 11058A with more convenient shielded banana plugs. The Fluke cable has the added Guard built in but be sure to also use a Guard lead with the Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY cables is usually not a good idea because the lead wire to terminal also constitutes just as critical of junction. The above cables use Tellurium Copper wire which is usually hard to find and hard to crimp properly and NEVER solder. 11058A and 11174A are discontinued at Keysight. However, Pomona 5295 spade to banana cables are available (5295-36 at Mouser et al) and claim that they are designed to minimize thermal EMFs. Datasheet is here: http://www.mouser.com/ds/2/159/d5295_1_01-51722.pdf Any comments on these as an alternative? Orin. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Randy: Sorry my fault. You have to use the RMATH command to get the various values stored in the registers. See the RMATH command in the User's Guide for a list of what registers you can read. I sure haven't found any other guides other than the 4 manuals. User's Guide, Quick Reference Guide, Calibration Manual, and Assembly Level Repair. It is just a matter of reading the guides and trying to remember what commands are available. It took me a lot of time to figure out what commands I use now. I am sure I am missing other commands that might be useful. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 6:04 PM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables
Re: [volt-nuts] 732A and Prologix received
Tellurium Copper is usually not used for a device's terminal posts but used as the lead wire due, as you say, for the malleability to crimp well and flexibility. The point I was making is to use the same interconnect test lead material throughout as the DUT terminal posts. The 3458A and the 732A both use Beryllium Copper alloy making that type interconnect lug or plug the best choice to minimize the dissimilar metal EMF or Seebeck voltage. The 34420A uses pure copper rather than an alloy terminal and for the same reason, minimal Seebeck voltage is realized with a pure copper interconnect. Any type of Silver or Gold plating on the terminal or wire will introduce the undesirable dissimilar metal properties, both at the plating junction and at the plating metal to DUT terminal. The NI website had this chart that quantifies the Seebeck voltage best: When two, dissimilar metals are joined a voltage is created. This voltage is known as the thermal electromotive force (EMF) or the Seebeck voltage. The Seebeck voltage is dependent on the temperature of the junction and the composition of the metals joined. The specific metal-to-metal junctions result in specific temperature coefficients (µV/°C), also known as Seebeck coefficients. The following table lists the most common metals and their respective Seebeck coefficients. JunctionµV/°C Copper-Copper 0.3 Copper-Gold 0.5 Copper-Silver 0.5 Copper-Brass3 Copper-Nickel 10 Copper-Lead-Tin Solder 1-3 Copper-Aluminum 5 Copper-Kovar40 Copper-Copper Oxide 500 Granted, Gold and Silver are the next best choice, and is certainly why they are satisfactory, but using either warrants a more critical temperature gradient issue. If your measurements were satisfactorily convincing, than you probably had no appreciable junction temperature differences. Don Johnson -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of acb...@gmx.de Sent: Monday, August 25, 2014 5:37 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received I have used the pomona spades, mainly to interface the low emf pomona banana cables to binding posts. I have stopped this, reasons being, they are large and worse, that the pomona spring loaded insulation tube that covers the banana plug conductor uses such a strong spring that slowly the plug works its way out of the spade. this btw also happend to me when I used the pomona low emf binding posts together with the pomona low emf banana cables. overall I m not happy with these. so, due to lack of options, I changed to self-made twisted shielded pair of high grade teflon/kapton silver plated copper cable with gold plated copper spades (crimped). I use them not only with the 3458a but also with nanovolt meters. these have higher resolution and accuracy in low level measurements than the 3458a. emf voltages were never an issue with these cables if properly used. I have posted some results doing 34420a stabilty measurements on the pmel forum, and the results are convincing (purpose was actually not to test the cables but the stability of the 34420a, but the emf issue is a part of this of course. we use the 34420a to do low voltage precision measurements on thermal converters where the full scale signal sometimes is 1mV). that btw also relates to don's statements below, I do not concurr with his comments about copper telurium as cable and spade material and so on. this material, as stated here many times, is used because it is machinable, for copper spades one would not use it. the 34420a factory cable uses copper cable and copper spades, not telurium-copper. if there was a problem, it would be worse with the 34420a than with the 3458a because of its low level ranges. and again, I have not seen any problems in a chain of (output to input): 1.copper-tellurium post from e.g. 8 digit calibrator 2.crimped copper spade, gold plated 3.silver plated tsp copper cable 4a.crimped copper spade to copper-tellurium post or 4b.soldered copper connector(34420) my consistent results over more than a year using them. Gesendet: Montag, 25. August 2014 um 06:33 Uhr Von: Orin Eman orin.e...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received On Sun, Aug 24, 2014 at 1:46 PM, Don@True-Cal truecalservi...@gmail.com wrote: Randy all, You have correctly concluded that some (maybe not all) of your measurement problem is thermal EMF being added or subtracted in series within your measurement interconnect. This thermal EMF is generated at the junction of dissimilar metals when accompanied with thermal gradients between the test lead and device terminals. You have to eliminate both the dissimilarity of the metal junctions as well as minimize the thermal differences. The terminals
Re: [volt-nuts] 732A and Prologix received
well, your last point is the issue, how can you have a temperature difference within a few microns of material in said connections. theory is one thing, but in reality it does not happen due to the givens of the setup. therefore in practice it is irrelevant if the wire is silver or gold plated or pure copper. otherwise the gold plated spades and tellurium copper posts from pomona and others would be nonsense. and other than the mysterious fluke wire I have never seen a tellurium-copper wire from any wire manufacturer. Gesendet: Montag, 25. August 2014 um 17:02 Uhr Von: Don@True-Cal truecalservi...@gmail.com An: 'Discussion of precise voltage measurement' volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Tellurium Copper is usually not used for a device's terminal posts but used as the lead wire due, as you say, for the malleability to crimp well and flexibility. The point I was making is to use the same interconnect test lead material throughout as the DUT terminal posts. The 3458A and the 732A both use Beryllium Copper alloy making that type interconnect lug or plug the best choice to minimize the dissimilar metal EMF or Seebeck voltage. The 34420A uses pure copper rather than an alloy terminal and for the same reason, minimal Seebeck voltage is realized with a pure copper interconnect. Any type of Silver or Gold plating on the terminal or wire will introduce the undesirable dissimilar metal properties, both at the plating junction and at the plating metal to DUT terminal. The NI website had this chart that quantifies the Seebeck voltage best: When two, dissimilar metals are joined a voltage is created. This voltage is known as the thermal electromotive force (EMF) or the Seebeck voltage. The Seebeck voltage is dependent on the temperature of the junction and the composition of the metals joined. The specific metal-to-metal junctions result in specific temperature coefficients (µV/°C), also known as Seebeck coefficients. The following table lists the most common metals and their respective Seebeck coefficients. Junction µV/°C Copper-Copper 0.3 Copper-Gold 0.5 Copper-Silver 0.5 Copper-Brass 3 Copper-Nickel 10 Copper-Lead-Tin Solder 1-3 Copper-Aluminum 5 Copper-Kovar 40 Copper-Copper Oxide 500 Granted, Gold and Silver are the next best choice, and is certainly why they are satisfactory, but using either warrants a more critical temperature gradient issue. If your measurements were satisfactorily convincing, than you probably had no appreciable junction temperature differences. Don Johnson -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of acb...@gmx.de Sent: Monday, August 25, 2014 5:37 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received I have used the pomona spades, mainly to interface the low emf pomona banana cables to binding posts. I have stopped this, reasons being, they are large and worse, that the pomona spring loaded insulation tube that covers the banana plug conductor uses such a strong spring that slowly the plug works its way out of the spade. this btw also happend to me when I used the pomona low emf binding posts together with the pomona low emf banana cables. overall I m not happy with these. so, due to lack of options, I changed to self-made twisted shielded pair of high grade teflon/kapton silver plated copper cable with gold plated copper spades (crimped). I use them not only with the 3458a but also with nanovolt meters. these have higher resolution and accuracy in low level measurements than the 3458a. emf voltages were never an issue with these cables if properly used. I have posted some results doing 34420a stabilty measurements on the pmel forum, and the results are convincing (purpose was actually not to test the cables but the stability of the 34420a, but the emf issue is a part of this of course. we use the 34420a to do low voltage precision measurements on thermal converters where the full scale signal sometimes is 1mV). that btw also relates to don's statements below, I do not concurr with his comments about copper telurium as cable and spade material and so on. this material, as stated here many times, is used because it is machinable, for copper spades one would not use it. the 34420a factory cable uses copper cable and copper spades, not telurium-copper. if there was a problem, it would be worse with the 34420a than with the 3458a because of its low level ranges. and again, I have not seen any problems in a chain of (output to input): 1.copper-tellurium post from e.g. 8 digit calibrator 2.crimped copper spade, gold plated 3.silver plated tsp copper cable 4a.crimped copper spade to copper-tellurium post or 4b.soldered copper connector(34420) my consistent
Re: [volt-nuts] 732A and Prologix received
On 8/25/2014 11:02 AM, Don@True-Cal wrote: Silver or Gold plating on the terminal or wire will introduce the undesirable dissimilar metal properties, both at the plating junction and at the plating metal to DUT terminal. Why? Any Seebeck effect is immediately offset in the opposite direction, since both junctions are (under normal conditions) at essentially the same temperature (e.g. there's a copper-gold thermocouple, the minimal thermal resistance of a micron of gold on the contact(s), then a gold-copper thermocouple). It seems to me that the improved consistency of the contact outweighs any loss from the thermocouples. A more typical contact would be copper-nickel plate-gold plate, but the concept is the same. Unless there is heat flowing through the entire assembly so one thermocouple is warmer than the offsetting one (e.g. shortly after plugging in a banana plug warmed by body heat), they simply cancel. Even if connecting gold plated to nickel plated contacts, it works out the same - a copper-nickel-gold-nickel-copper connection is completely offset. It's when the offsetting thermocouples occur across a temperature gradient that you have problems. -- Mike ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Why? Let me count the ways. You can never count on any Seebeck voltage to be immediately offset, there are far too many variables. Best example I can think of...why is there an Ohms Offset Compensation feature on any good high resolution DMM. 1) Try measuring a 1 or 10 Ohm resistor with your 3458A in 4-wire mode using inexpensive nickel-plated leads and even allow plenty of time for everything to thermally stabilize. Using Ohms Offset Compensation, enable and disable it and observe the difference. If the Seebeck voltages were all immediately offset, as you say, there would be no difference. But there most certainly is. Or simply, why is there a need for ohms offset compensation feature if all Seebeck voltages cancel each other out. Sure, nickel-plated is a horrible choice but if it all canceled, what difference would it make how bad is. 2) The cal lab workhorse calibrator is the 5700A/5720A. In between trips back to Fluke for full calibration, there is an interim external calibration procedure using the 732B, 742A-1 742A-10k. If someone used a set of gold-plated interconnects for this procedure, they would be laughed out of the lab and the calibrator would be useless until recalibrated properly. A set of 5440A-7002 (banana plug) cables comes with this calibrator (5440A-7003 spade lugs for 5720A) and recommended for the calibration procedure but other Beryllium Copper or pure Copper cables are also acceptable. 3) Lab air drafts will never allow true thermal symmetry around the DMM or DUT terminals. To convince yourself, place an oscillating fan several feet back from the DMM and DUT terminals and using the 1 or 10 Ohm setup from above, again with the nickel-plated leads, watch the variations. Sure the fan and the nickel-plated exaggerates the issue but it quickly dispels the notion that all the Seebeck voltages are canceled out. BTW, the plating layer temperature on a plated terminal will be somewhere between the temperature of the base metal and mating terminal it's connected to. This is not just theory, my 40+ years in the cal lab is driving my arguments but it never hurts to have physical-science on your side. Don Johnson -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Mike S Sent: Monday, August 25, 2014 11:03 AM To: volt-nuts@febo.com Subject: Re: [volt-nuts] 732A and Prologix received On 8/25/2014 11:02 AM, Don@True-Cal wrote: Silver or Gold plating on the terminal or wire will introduce the undesirable dissimilar metal properties, both at the plating junction and at the plating metal to DUT terminal. Why? Any Seebeck effect is immediately offset in the opposite direction, since both junctions are (under normal conditions) at essentially the same temperature (e.g. there's a copper-gold thermocouple, the minimal thermal resistance of a micron of gold on the contact(s), then a gold-copper thermocouple). It seems to me that the improved consistency of the contact outweighs any loss from the thermocouples. A more typical contact would be copper-nickel plate-gold plate, but the concept is the same. Unless there is heat flowing through the entire assembly so one thermocouple is warmer than the offsetting one (e.g. shortly after plugging in a banana plug warmed by body heat), they simply cancel. Even if connecting gold plated to nickel plated contacts, it works out the same - a copper-nickel-gold-nickel-copper connection is completely offset. It's when the offsetting thermocouples occur across a temperature gradient that you have problems. -- Mike ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Not that I know of. Just wait and when you don't see a SMPL on the display it is done. But then with 1000 PLC that is around 16.66 seconds per reading times 100 readings is somewhere around 28 minutes and there is probably some overhead time so around 30 minutes. Not from the front panel at any rate. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Monday, August 25, 2014 9:23 PM Subject: Re: [volt-nuts] 732A and Prologix received Is there any way to tell when the function key routine is complete? In the case of taking multiple readings using the DEFKEY and MATH function, I don't see any indication when the routine is complete. In one particular case, I am taking a 100 readings with NLPC set for 1000 so its a long while before it's complete, but i have to guess when it's done. Thanks, Randy On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got
Re: [volt-nuts] 732A and Prologix received
: Friday, August 22, 2014 9:03 PM Subject: Re: [volt-nuts] 732A and Prologix received Todd, Thanks for the info. I have several Panasonic 12V 7 AH batteries that I keep topped off and they have very low current draw (~2 to 3 mA at 13.5 VDC) when charged and at their float voltage, so I am pretty sure they are in good condition. I will look at getting those in the units after I ascertain the condition of the 732. So now I have a what appears to be a functioning 3458A and a 732A but they slightly disagree. I am like the man with two watches that disagree on the time - which is correct? For the moment, i am only concerned with stability. The need for absolute accuracy will come later. Randy On Fri, Aug 22, 2014 at 8:06 PM, Todd Micallef tmical...@gmail.com wrote: Randy, You have two possible choices. It can be configured with 4 x 6v 4Ah batteries or 2 x 12v 7Ah batteries. Hopefully the previous owner has modified the battery pack already. A couple of mine needed a nibbler tool to remove enough of the aluminum cover that fits over the tops of the batteries. The original cover will short out to the battery tabs regardless of the battery configuration if this is not done. You can find larger capacity batteries that will give you slightly more battery life. I lost a couple sets of mail-order batteries after a few extended outages. I would recommend going with locally bought batteries instead of the cheaper mail order. My local Batteries Plus will typically have some warranty if I remember correctly. Moving forward I will only use 2 12v batteries and pre-charge them on a battery charger to equalize them before putting them in the 732A. I think the cheap batteries did not discharge equally, and would not recover when power was applied. Inspect the back plane for damaged traces and look at the capacitors. I had a few that looked questionable. So far, I have replaced all the big caps on the pre-regulator and regulator boards. My feeling is that once these go online, they should run as long as possible between repairs. The battery charger circuit may need adjusting. I tweaked mine and it seemed to work fine. Todd On Fri, Aug 22, 2014 at 10:42 PM, Randy Evans randyevans2...@gmail.com wrote: I received my Fluke 732A today. Just powered it up but it needs new batteries. Any suggestions for sources (I haven't opened up the unit yet - I want to make sure it works before doing that). Also received the ProLogix USB-GPIB adapter. I plan on using Mark Sims' CAL ran data dumper program to get the CAL data from my 3458A. Should be a busy weekend. Randy ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Bill, I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes, I was mistaken. The 12V 5ah batteries are the ones that I am using in one of my 732A. There is more play inside the tray with the 12v batteries by several mm as compared to the 6v which only has a 2-3mm. The 12v conversion is not difficult, but it is easier if the battery tray has already been machined for the 12v batteries. The battery tabs don't line up well with the existing holes and need to be widened. Two additional holes must also be added. Sourcing the batteries locally is more of a convenience than waiting for the delivery. The el-cheapo 6v batteries are a waste of money and I have 8 batteries so far to prove it. They died the first time I had a 6hr outage and would not hold a charge after that. Todd On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost and then restored, even months later, the 732A will come back to almost exactly the same 10 volts as when they lost power, usually with in 0.2 PPM after 24 hours of warm up. What type of hookup leads are you using when measuring the 1 volt output? What is the PLC set to? I always use 100 PLC to measure this. If you don't have low thermal connection leads you can experience uV changes for a minute or more after plugging in the leads due to the thermals generated because of the difference in temperature between the banana jacks on the 732A and the banana plugs of the leads. I have found that even just plugging in the lead will generate a thermal difference because of difference of temps and some heating due to the physical act of just inserting the plug because of friction between the jack and plug (my theory at any rate). You have to allow at least a minute or more before being able to make a measurement after plugging in the leads. I just measured the variation of the 1 volt output of my 732A and using my 3458A and I got a total difference of 0.159 uV over 40 measurements using 100 PLC on the 1 volt range of the 3458A. Using the MATH function and all of the data you can collect. That was after waiting for several minutes after plugging in the leads. I hope all of this helps. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Friday, August 22, 2014 9:03 PM Subject: Re: [volt-nuts] 732A and Prologix received Todd, Thanks for the info. I have several Panasonic 12V 7 AH batteries that I keep topped off
Re: [volt-nuts] 732A and Prologix received
experience uV changes for a minute or more after plugging in the leads due to the thermals generated because of the difference in temperature between the banana jacks on the 732A and the banana plugs of the leads. I have found that even just plugging in the lead will generate a thermal difference because of difference of temps and some heating due to the physical act of just inserting the plug because of friction between the jack and plug (my theory at any rate). You have to allow at least a minute or more before being able to make a measurement after plugging in the leads. I just measured the variation of the 1 volt output of my 732A and using my 3458A and I got a total difference of 0.159 uV over 40 measurements using 100 PLC on the 1 volt range of the 3458A. Using the MATH function and all of the data you can collect. That was after waiting for several minutes after plugging in the leads. I hope all of this helps. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Friday, August 22, 2014 9:03 PM Subject: Re: [volt-nuts] 732A and Prologix received Todd, Thanks for the info. I have several Panasonic 12V 7 AH batteries that I keep topped off and they have very low current draw (~2 to 3 mA at 13.5 VDC) when charged and at their float voltage, so I am pretty sure they are in good condition. I will look at getting those in the units after I ascertain the condition of the 732. So now I have a what appears to be a functioning 3458A and a 732A but they slightly disagree. I am like the man with two watches that disagree on the time - which is correct? For the moment, i am only concerned with stability. The need for absolute accuracy will come later. Randy On Fri, Aug 22, 2014 at 8:06 PM, Todd Micallef tmical...@gmail.com wrote: Randy, You have two possible choices. It can be configured with 4 x 6v 4Ah batteries or 2 x 12v 7Ah batteries. Hopefully the previous owner has modified the battery pack already. A couple of mine needed a nibbler tool to remove enough of the aluminum cover that fits over the tops of the batteries. The original cover will short out to the battery tabs regardless of the battery configuration if this is not done. You can find larger capacity batteries that will give you slightly more battery life. I lost a couple sets of mail-order batteries after a few extended outages. I would recommend going with locally bought batteries instead of the cheaper mail order. My local Batteries Plus will typically have some warranty if I remember correctly. Moving forward I will only use 2 12v batteries and pre-charge them on a battery charger to equalize them before putting them in the 732A. I think the cheap batteries did not discharge equally, and would not recover when power was applied. Inspect the back plane for damaged traces and look at the capacitors. I had a few that looked questionable. So far, I have replaced all the big caps on the pre-regulator and regulator boards. My feeling is that once these go online, they should run as long as possible between repairs. The battery charger circuit may need adjusting. I tweaked mine and it seemed to work fine. Todd On Fri, Aug 22, 2014 at 10:42 PM, Randy Evans randyevans2...@gmail.com wrote: I received my Fluke 732A today. Just powered it up but it needs new batteries. Any suggestions for sources (I haven't opened up the unit yet - I want to make sure it works before doing that). Also received the ProLogix USB-GPIB adapter. I plan on using Mark Sims' CAL ran data dumper program to get the CAL data from my 3458A. Should be a busy weekend. Randy ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Randy all, You have correctly concluded that some (maybe not all) of your measurement problem is thermal EMF being added or subtracted in series within your measurement interconnect. This thermal EMF is generated at the junction of dissimilar metals when accompanied with thermal gradients between the test lead and device terminals. You have to eliminate both the dissimilarity of the metal junctions as well as minimize the thermal differences. The terminals of the 3458A as well as the 732A are Beryllium Copper so you want to use the same test lead terminals. Forget the typical Tin plated lugs or even Gold plated as both are not Beryllium Copper and constitute dissimilar metals. The best solution (as usually the most expensive) is to use a set of Fluke 5440A-7005 (48) cables. I also have just as good results using the much more flexible Pomona 11174A (lugs end always stay connected to the 732A) or 11058A with more convenient shielded banana plugs. The Fluke cable has the added Guard built in but be sure to also use a Guard lead with the Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY cables is usually not a good idea because the lead wire to terminal also constitutes just as critical of junction. The above cables use Tellurium Copper wire which is usually hard to find and hard to crimp properly and NEVER solder. As you observed, merely the friction of plugging in the spring banana plug and heat transfer from your fingers will require ~3-5 minutes to stabilize. Low mass terminals help with the time to initially stabilize but is not best if dealing with local air current drafts that upset the instantaneous thermal gradients between the higher mass device terminal and the lower mass lead terminal. This issue is a trade-off and is specifically considered in the Fluke cables but being careful with localized drafts around the terminals during critical measurements can virtually eliminate this error source. I have attached an ~30-hour measurement run that I consistently do that should give you some idea of expected measurement drift over time. Virtually all of the measurement drift is due to the 3458A internal temperature differences around the 7V reference caused by ambient temperature change. The drift associated with the 732A is probably about 2-magnitudes less at this ambient temp drift. In my situation, the inferred ambient temperature is cycling with the home air-conditioning. Note the initial calibration temperatures as well as the ACal temperatures and where the 3458A is measuring exactly 10V. My primary 732A has been powered without loss for 4 years and 5 years before that. The 3458A is Agilent (Loveland) Cal'ed yearly and is powered 24-7-365 except for the occasional mains power loss. The graphical measurements is using a homegrown Agilent VEE program. Don Johnson -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Randy Evans Sent: Sunday, August 24, 2014 9:22 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly
Re: [volt-nuts] 732A and Prologix received
Todd: I check the batteries every month per the 732A manual. Usually I keep a few used cells from previous packs around that seem to be ok after checking them for capacity just like checking the battery pack. I can usually spot cells going bad with that method. If I don't have a spare set then I just substitute a used cell until I receive a new set. I agree with you that the cheap ones are crap. I have used Power Sonic a lot with some a few EaglePicher and one set of Enersys. The EaglePicher are crap so I will never use them. EaglePicher have had a couple out of 8 that have failed very early. I have never tried Panasonic. So I stick with the Power Sonic's. I am not sure why the 12 volt ones would be better than the 6 volts because 12 volt is just 6 lead acid cells while the 6volt are 3 lead acid cells. If one of the 6 cells in the 12 volt battery go bad then the whole battery has to be changed. So you better buy good quality 12 volt batteries. I just can't seem to source batteries locally easily at a reasonable price. So I order them from Allied usually. Bill - Original Message - From: Todd Micallef tmical...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 8:13 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes, I was mistaken. The 12V 5ah batteries are the ones that I am using in one of my 732A. There is more play inside the tray with the 12v batteries by several mm as compared to the 6v which only has a 2-3mm. The 12v conversion is not difficult, but it is easier if the battery tray has already been machined for the 12v batteries. The battery tabs don't line up well with the existing holes and need to be widened. Two additional holes must also be added. Sourcing the batteries locally is more of a convenience than waiting for the delivery. The el-cheapo 6v batteries are a waste of money and I have 8 batteries so far to prove it. They died the first time I had a 6hr outage and would not hold a charge after that. Todd On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost and then restored, even months later, the 732A will come back to almost exactly the same 10 volts as when they lost power, usually with in 0.2 PPM after 24 hours of warm up. What type of hookup leads are you using when measuring the 1 volt output? What is the PLC set to? I always
Re: [volt-nuts] 732A and Prologix received
Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used
Re: [volt-nuts] 732A and Prologix received
Bill, Thanks for the MATH overview. That could be very helpful. I definately will give it a try. Randy On Sun, Aug 24, 2014 at 2:44 PM, Bill Gold wpgold3...@att.net wrote: Todd: I check the batteries every month per the 732A manual. Usually I keep a few used cells from previous packs around that seem to be ok after checking them for capacity just like checking the battery pack. I can usually spot cells going bad with that method. If I don't have a spare set then I just substitute a used cell until I receive a new set. I agree with you that the cheap ones are crap. I have used Power Sonic a lot with some a few EaglePicher and one set of Enersys. The EaglePicher are crap so I will never use them. EaglePicher have had a couple out of 8 that have failed very early. I have never tried Panasonic. So I stick with the Power Sonic's. I am not sure why the 12 volt ones would be better than the 6 volts because 12 volt is just 6 lead acid cells while the 6volt are 3 lead acid cells. If one of the 6 cells in the 12 volt battery go bad then the whole battery has to be changed. So you better buy good quality 12 volt batteries. I just can't seem to source batteries locally easily at a reasonable price. So I order them from Allied usually. Bill - Original Message - From: Todd Micallef tmical...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 8:13 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes, I was mistaken. The 12V 5ah batteries are the ones that I am using in one of my 732A. There is more play inside the tray with the 12v batteries by several mm as compared to the 6v which only has a 2-3mm. The 12v conversion is not difficult, but it is easier if the battery tray has already been machined for the 12v batteries. The battery tabs don't line up well with the existing holes and need to be widened. Two additional holes must also be added. Sourcing the batteries locally is more of a convenience than waiting for the delivery. The el-cheapo 6v batteries are a waste of money and I have 8 batteries so far to prove it. They died the first time I had a 6hr outage and would not hold a charge after that. Todd On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost
Re: [volt-nuts] 732A and Prologix received
Bill, I am trying to figure out the MATH function without much success. The 3458 On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect
Re: [volt-nuts] 732A and Prologix received
Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am
Re: [volt-nuts] 732A and Prologix received
Hi Randy, You can use the NPLC command to change the A/D converter's'integration time. Set it to 1000 if you want full resolution. It sets the hp3458a's NMR. Charlie On 8/24/2014 6:04 PM, Randy Evans wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability
Re: [volt-nuts] 732A and Prologix received
On Sun, Aug 24, 2014 at 1:46 PM, Don@True-Cal truecalservi...@gmail.com wrote: Randy all, You have correctly concluded that some (maybe not all) of your measurement problem is thermal EMF being added or subtracted in series within your measurement interconnect. This thermal EMF is generated at the junction of dissimilar metals when accompanied with thermal gradients between the test lead and device terminals. You have to eliminate both the dissimilarity of the metal junctions as well as minimize the thermal differences. The terminals of the 3458A as well as the 732A are Beryllium Copper so you want to use the same test lead terminals. Forget the typical Tin plated lugs or even Gold plated as both are not Beryllium Copper and constitute dissimilar metals. The best solution (as usually the most expensive) is to use a set of Fluke 5440A-7005 (48) cables. I also have just as good results using the much more flexible Pomona 11174A (lugs end always stay connected to the 732A) or 11058A with more convenient shielded banana plugs. The Fluke cable has the added Guard built in but be sure to also use a Guard lead with the Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY cables is usually not a good idea because the lead wire to terminal also constitutes just as critical of junction. The above cables use Tellurium Copper wire which is usually hard to find and hard to crimp properly and NEVER solder. 11058A and 11174A are discontinued at Keysight. However, Pomona 5295 spade to banana cables are available (5295-36 at Mouser et al) and claim that they are designed to minimize thermal EMFs. Datasheet is here: http://www.mouser.com/ds/2/159/d5295_1_01-51722.pdf Any comments on these as an alternative? Orin. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Randy, I have replaced batteries in two units so far, which I bought on ebay (6V) and they fitted absolutelly perfect, no need to rework an metal and there was o isue with shortages. So there certainly are standard 6V batteries that fit without mods. I always try to keep things in original config, if possible. Also, you do not want to adjust the 732a trimmers. It only gets unstable, if you are unlucky. I discussed this with some cal labs, same answer. What you could do is to adjust the jumper settings for coarse adjustment, if need be. Adrian Gesendet: Samstag, 23. August 2014 um 04:03 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] 732A and Prologix received Todd, Thanks for the info. I have several Panasonic 12V 7 AH batteries that I keep topped off and they have very low current draw (~2 to 3 mA at 13.5 VDC) when charged and at their float voltage, so I am pretty sure they are in good condition. I will look at getting those in the units after I ascertain the condition of the 732. So now I have a what appears to be a functioning 3458A and a 732A but they slightly disagree. I am like the man with two watches that disagree on the time - which is correct? For the moment, i am only concerned with stability. The need for absolute accuracy will come later. Randy On Fri, Aug 22, 2014 at 8:06 PM, Todd Micallef tmical...@gmail.com wrote: Randy, You have two possible choices. It can be configured with 4 x 6v 4Ah batteries or 2 x 12v 7Ah batteries. Hopefully the previous owner has modified the battery pack already. A couple of mine needed a nibbler tool to remove enough of the aluminum cover that fits over the tops of the batteries. The original cover will short out to the battery tabs regardless of the battery configuration if this is not done. You can find larger capacity batteries that will give you slightly more battery life. I lost a couple sets of mail-order batteries after a few extended outages. I would recommend going with locally bought batteries instead of the cheaper mail order. My local Batteries Plus will typically have some warranty if I remember correctly. Moving forward I will only use 2 12v batteries and pre-charge them on a battery charger to equalize them before putting them in the 732A. I think the cheap batteries did not discharge equally, and would not recover when power was applied. Inspect the back plane for damaged traces and look at the capacitors. I had a few that looked questionable. So far, I have replaced all the big caps on the pre-regulator and regulator boards. My feeling is that once these go online, they should run as long as possible between repairs. The battery charger circuit may need adjusting. I tweaked mine and it seemed to work fine. Todd On Fri, Aug 22, 2014 at 10:42 PM, Randy Evans randyevans2...@gmail.com wrote: I received my Fluke 732A today. Just powered it up but it needs new batteries. Any suggestions for sources (I haven't opened up the unit yet - I want to make sure it works before doing that). Also received the ProLogix USB-GPIB adapter. I plan on using Mark Sims' CAL ran data dumper program to get the CAL data from my 3458A. Should be a busy weekend. Randy ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost and then restored, even months later, the 732A will come back to almost exactly the same 10 volts as when they lost power, usually with in 0.2 PPM after 24 hours of warm up. What type of hookup leads are you using when measuring the 1 volt output? What is the PLC set to? I always use 100 PLC to measure this. If you don't have low thermal connection leads you can experience uV changes for a minute or more after plugging in the leads due to the thermals generated because of the difference in temperature between the banana jacks on the 732A and the banana plugs of the leads. I have found that even just plugging in the lead will generate a thermal difference because of difference of temps and some heating due to the physical act of just inserting the plug because of friction between the jack and plug (my theory at any rate). You have to allow at least a minute or more before being able to make a measurement after plugging in the leads. I just measured the variation of the 1 volt output of my 732A and using my 3458A and I got a total difference of 0.159 uV over 40 measurements using 100 PLC on the 1 volt range of the 3458A. Using the MATH function and all of the data you can collect. That was after waiting for several minutes after plugging in the leads. I hope all of this helps. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Friday, August 22, 2014 9:03 PM Subject: Re: [volt-nuts] 732A and Prologix received Todd, Thanks for the info. I have several Panasonic 12V 7 AH batteries that I keep topped off and they have very low current draw (~2 to 3 mA at 13.5 VDC) when charged and at their float voltage, so I am pretty sure they are in good condition. I will look at getting those in the units after I ascertain the condition of the 732. So now I have a what appears to be a functioning 3458A and a 732A but they slightly disagree. I am like the man with two watches that disagree on the time - which is correct? For the moment, i am only concerned with stability. The need for absolute accuracy will come later. Randy On Fri, Aug 22, 2014 at 8:06 PM, Todd Micallef tmical...@gmail.com wrote: Randy, You have two possible choices. It can be configured with 4 x 6v 4Ah batteries or 2 x 12v 7Ah batteries. Hopefully the previous owner has modified the battery pack already. A couple of mine needed a nibbler tool to remove enough of the aluminum cover that fits over the tops of the batteries. The original cover will short
