Re: [volt-nuts] AC calibration
what nist means is that a precision meter is not considered a standard. you always measure against a true standard (732a, esi sr104...). nist does not mean that as part of doing equipment calibration a 3458a cannot be used as aid. also keep in mind nist has a different approach than a cal lab, for obvious reasons. a cal lab would do a transfer measurement using a 3458a and a voltage/current source, sure. there are precision ratio transformers available from various vendors, they can be used for low frequency precision calibrations, up to 20khz only (if anybodys knows one specified above 20khz I am interested to hear). so they will help you only partially in calibrating even a low precision 5101. Gesendet: Mittwoch, 27. August 2014 um 07:08 Uhr Von: pa4...@gmail.com An: volt-nuts volt-nuts@febo.com Betreff: Re: [volt-nuts] AC calibration Thanks, I did not new NIST has so much interesting information on their site. I read the following on their site : multirange instruments with up to eight decimal digits of adjustability, are not considered by NIST to be standards Does that mean a HP3458 ? Fluke in the Netherlands used a HP-3458 and a 732 to calibrate the Fluke 5101 that I'm working on at this moment (it failed calibration due to some hardware faults) Everybody thanks for the information. Turns out, a friend has a GR 1455AH for me, that is some kind a AC KV divider. I will test if the output of my HP 3400 is usable to connect a DMM. I have one I restored a few years ago. Besides that someone mentioned to look at the LT-1088. But that has to wait until I have some more time. I only repaired calibration, percission gear and RF stuff for my hobby, but, not planned, I started to do this on a commercial base too. See my (non commercial) site about my collection calibration and other gear and projects www.pa4tim.nl . Today the 5101 goes back to the custommer but he brings 2 other instruments in need of some TLC and a precheck before they are shipped to Fluke for calibration. And yesterday an other company asked if I want/can repair a GM safety tester (a sort of megger on steroids) that died during calibration. Fred ___ 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 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
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. Of
Re: [volt-nuts] AC calibration
Fred, The 3458A is 8.5 digits, which puts it into the standards category. They are used as lab standards in many, many labs. 73, Steve WB0DBS On Aug 27, 2014, at 12:08 AM, pa4...@gmail.com wrote: Thanks, I did not new NIST has so much interesting information on their site. I read the following on their site : multirange instruments with up to eight decimal digits of adjustability, are not considered by NIST to be standards Does that mean a HP3458 ? Fluke in the Netherlands used a HP-3458 and a 732 to calibrate the Fluke 5101 that I'm working on at this moment (it failed calibration due to some hardware faults) Everybody thanks for the information. Turns out, a friend has a GR 1455AH for me, that is some kind a AC KV divider. I will test if the output of my HP 3400 is usable to connect a DMM. I have one I restored a few years ago. Besides that someone mentioned to look at the LT-1088. But that has to wait until I have some more time. I only repaired calibration, percission gear and RF stuff for my hobby, but, not planned, I started to do this on a commercial base too. See my (non commercial) site about my collection calibration and other gear and projects www.pa4tim.nl . Today the 5101 goes back to the custommer but he brings 2 other instruments in need of some TLC and a precheck before they are shipped to Fluke for calibration. And yesterday an other company asked if I want/can repair a GM safety tester (a sort of megger on steroids) that died during calibration. Fred Verzonden met Windows Mail Van: acb...@gmx.de Verzonden: dinsdag 26 augustus 2014 18:56 Aan: volt-nuts Dave, the title is: Thermal Voltage Converters and Comparator for Very Accurate AC Voltage Measurements by E.S.Williams. Adrian Gesendet: Montag, 25. August 2014 um 19:32 Uhr Von: Dave M dgmin...@mediacombb.net An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] AC calibration Adrian, Do you have a link or title for the NIST paper that you mentioned? Dave M acb...@gmx.de wrote: fred, generally you raise a good point, I had the same issue of calibrating an ac voltage to a high level of accuracy. you need this e.g. to validate the self.cal of a 3458a or other precison stuff like the 8506a0. what i would recommend to do if you want to keep costs down is: in a nutshell, get a thermal converter in the lowest range you need and a second one on range above. build a set of resistor range extenders (rf type with appropriate connectors and housings) to expand the range to where you need to be max. get one of the thermal converter calibrated (the higher one usually, and you need to havr good cal lab, should be 10ppm accuracy) and use it to calibrate the rest. generally, up to 20khz, the accuracy is some 20 ppm anyway for thermal converters! at higher frequencies, due to reflections and stray capacitance/inductance influences, the accuracy decreases. the resistor range extenders though, if build up correctly, only have a few ppm impact (there is a paper from nist on that, but this is only typical). you can calibrate all converters to the one you got externally calibrated. do some research in the web, when you do the calibration, you need to determine the so-called constant N. then do an ac, dc+, ac, dc-, ac measurement between the the two and establish the deviation, also establish the error propagation. the end result will be a set of highly precise (low inaccuracies9 thermal converters good enough to calibrate a 3458a an better devices. if you want to spend the money, you could also buy a set of converters/range resistors (with/without a 540), that typically is a few k altogether, while a single device sometimes is available for below 100 bucks. you need to have a stable 7.5 digit nanovoltmeter though for the measurements of the tvcs (34420a or 2182 typically ) and precision (stable) dc and ac sources. but in the end, all you need is a single calibrated thermal converter. adrian Gesendet: Montag, 25. August 2014 um 18:38 Uhr Von: Dave M dgmin...@mediacombb.net An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] AC calibration Well, you sort of answered your own question. The equipment is called a Thermal Transfer Standard, but instead of thermistors, it uses a thermocouple. Look at the manual for the Fluke 540B (http://bama.edebris.com/manuals/fluke/540b/) and you'll see how it's done. Basically, the AC source is input into the transfer standard, and the standard's internal reference voltage is adjusted for a null on the galvanometer. Leaving the reference voltage setting alone, a DC voltage is input into the unit, and the DC source is adjusted for a null on the galvanometer. At that point, the AC voltage source is equal to
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 and
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 the
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
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
[volt-nuts] fluke 5200a extender board.
Hi all, Over the last 6 months I have been steadily repairing a faulty 5200A that I brought, it had numerous faults in the power supply regulator and power amplifier boards that I have managed to repair with a lot of difficulty as I do not have an extender board to operate the boards out of the chassis. I managed to overcome this by running numerous test leads to various points on the boards as I tested to enable me to take readings, but I have now got down to what looks like a problem on the attenuator board loading up the A7 power amplifier board and causing the +190 regulated supply to drop. The most likely cause is suggested as more than one attenuator path being selected at the same time, but I think it will be virtually impossible to trace the logic signals on and being supplied to the attenuator board without an extender board, so if anybody out there has one they are willing to sell please let me know! Alternatively it would be a great help if somebody could supply me with a full scale photo copy of both sides of the extender board so I can have a go at making one of my own. The 43/86 pin card edge sockets are no longer available as far as I can find out, the only company that lists any of them is Sullins Connectors but they are out of stock as well, so I cannot envisage them making any more in the near future, maybe somebody is parting out a 5200a? If I can make a pcb for the extender board then I think I can cobble up various parts to substitute for the card edge connector required. Thanks in advance for any replies. Ken Goodhew. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ 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] Using a DVM to adjust a 752A divider
Folks, Had some correspondence with Fluke a while back regarding adjustment of the 752A Reference Divider. They no longer sell the 845AB Null Detector but they have some suggestions on alternate meters to do the job. They also make reference to zeroing the inputs of the detector, which has been a hot topic lately. Here is the link: http://www.ko4bb.com/Manuals/Fluke/Fluke_-_Using_a_DMM_to_balance_752A_Divid er.pdf Best regards, mitch ___ 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.
