Re: [volt-nuts] 732A drift
Hi, first post! Yeah, I ran into this issue a while back. Fortunately for most applications 10mV resolution is fine (eg measuring charge state on Li-ion cells) but I did find that old meters do seem to experience random drift failures of precision resistors and more so trimpots. Would it be a good idea for someone to do a "732 FAQ" with likely faults that would cause a particular matrix of symptoms? Also how do you deal with failures where a precision component has "gone bad" ? Surely all the calibrations are suspect which is why any sensible engineer always has two references at a bare minimum and sets up a master/slave or main/backup then maintains a calibration table of each? so if a drift is seen then the "bad" unit can be dealt with sternly. I looked into making a 10.Vref a while back and had some success with active feedback via thermal pad: it almost worked but in the end it was cheaper and simpler to buy one ready made (cough REF02 /cough) Also relevant, since originally buying my RS IDM65 you can now get I2C precision CT references which can replace the troublesome parts with something that does not drift, ever! -Andre From: volt-nuts <volt-nuts-boun...@febo.com> on behalf of Alan Ambrose <alan.ambr...@anagram.net> Sent: 30 August 2017 17:33 To: volt-nuts@febo.com Subject: [volt-nuts] 732A drift >>> My 732A e.g. has a drift of only about 0.2ppm >>> pa over a couple of year Hope you don't mind me jumping on this thread and asking a basic question: is there any kind of procedure for the 'enthusiast' (say with single 3458A/single 732 and not say 4x732) to measure the drift of a particular 732. Alan ___ 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] 732A drift
>>> My 732A e.g. has a drift of only about 0.2ppm >>> pa over a couple of year Hope you don't mind me jumping on this thread and asking a basic question: is there any kind of procedure for the 'enthusiast' (say with single 3458A/single 732 and not say 4x732) to measure the drift of a particular 732. Alan ___ 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 drift
Randy, that is strange. two things come in mind that might be worth checking. first, is the mains frequency setting of the 3458a set to 60Hz (I assume you are in the US)? this is important to suppress mains ac disturbing the measurement. secondly, have you connected guard? tsp cables would be best to use. a general statment re. the 1V and 1.18V. they are much less stable than the 10V. My 732A e.g. has a drift of 0.2ppm/a. So I use a kelvin-varley divider if I need 1V. this is self calibrating, so you have maybe 0.1ppm worse accuracy. you could also use the 3458a linearity to re-characterize the 1v with reference to the 10V. That also gives you good accuracy. Also, I only have the 10V cal'ed on a regular basis to below 0.5ppm accuracy, that costs much less than haveing all three voltages cal'ed, which would not add any benefit anyway. Adrian Gesendet: Samstag, 23. August 2014 um 05:16 Uhr Von: Randy Evans randyevans2...@gmail.com An: volt-nuts@febo.com volt-nuts@febo.com Betreff: [volt-nuts] 732A drift I hope someone can help with a strange anomaly on either my 3458A or the 732A. The 732A 10V output as measured on my 3458A seems relatively stable over time (it bounces around about +/-1 uV but is it the 732 or the 3458?). However, the 1.000 VDC output drifts downward at a rate around 1-2 uV per second as soon as I plug the 3458A into the 732 output. If I remove the 3458A and connect it back up after a few 10s of seconds, the reading goes back to what it started at and then drifts downward again. The 1.018V output also drifts downward but at a much slower rate and not as much. Now the question is: is it the 732 or the 3458A? I tried to see it on my Agilent 34401A DMM but it really doesn't have the resolution, but I do seem to see it on the 1.000VDC output. If it is the 732A, what would cause it to drift downward like that? Since the 3458A has an input impedance of 10Gohm on the 1 and 10 V ranges, I wouldn't think the 732 would even see the difference of whether the 3458A is connected of not, but it clearly makes a difference as to how long its connected and how long it's been disconnected. Any one have any conjectures? Also, what will turn on the In Cal light? What does it mean if it doesn't come on? Thanks, 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.
Re: [volt-nuts] 732A drift
Randy, I looked at the 3458a input impedance, and it is difficult to get the meter set to the FixedZ (10M) mode. However, the 100v range is 10M. It should default to HiZ on reset. I forgot to mention to check the outputs and guard resistance to ground. One of my 732a had some foam baffling under the cover that had dry rotted. There was a lot of leakage to ground. I can't remember if the foam was on the older or newer versions of the 732a. The cal light comes on with a short wire stuck in the hole and connected to a LO output terminal. I don't know, but maybe the battery charge led has to be off. Todd Sent from my iPad On Aug 23, 2014, at 1:16, Randy Evans randyevans2...@gmail.com wrote: I hope someone can help with a strange anomaly on either my 3458A or the 732A. The 732A 10V output as measured on my 3458A seems relatively stable over time (it bounces around about +/-1 uV but is it the 732 or the 3458?). However, the 1.000 VDC output drifts downward at a rate around 1-2 uV per second as soon as I plug the 3458A into the 732 output. If I remove the 3458A and connect it back up after a few 10s of seconds, the reading goes back to what it started at and then drifts downward again. The 1.018V output also drifts downward but at a much slower rate and not as much. Now the question is: is it the 732 or the 3458A? I tried to see it on my Agilent 34401A DMM but it really doesn't have the resolution, but I do seem to see it on the 1.000VDC output. If it is the 732A, what would cause it to drift downward like that? Since the 3458A has an input impedance of 10Gohm on the 1 and 10 V ranges, I wouldn't think the 732 would even see the difference of whether the 3458A is connected of not, but it clearly makes a difference as to how long its connected and how long it's been disconnected. Any one have any conjectures? Also, what will turn on the In Cal light? What does it mean if it doesn't come on? Thanks, 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.
Re: [volt-nuts] 732A drift
The output impedance of both the 1v outputs is ~1k ohm. I wonder if Randy could check the 3458a input impedance with a 10M ohm resistor and the 10v output of the 732a. I was thinking that the 732a needed a minimum battery voltage to allow the in cal led to turn on with the short to the Lo terminal. I guess I could try it on one of mine that is waiting for repair. Todd Sent from my iPad On Aug 23, 2014, at 6:42, J. L. Trantham jlt...@att.net wrote: Randy, The 'IN CAL' LED is turned on as Todd describes. It goes off if power to the unit is lost and, thus, calibration is lost. It is not related to the battery charge LED. As I understand it, the units are designed to powered on 24/7/365 and are 'IN CAL' once they are powered up, stable (weeks, months?), and have been calibrated by your reference lab. Once power is lost, meaning lost AC and batteries depleted, the 'IN CAL' light goes out and outputs are thereafter unreliable. Once you decide to get the 732A calibrated, you will need to find a way to ship it to the reference lab and get it shipped back while continuously powered, connecting an external battery pack to the connector on the back of the battery pack. The internal battery pack is likely to last only a few hours. There are at least two types of connectors for an external battery, two 5 way binding posts and a Hypertronics connector which is a small black connector about 'dime' sized. I can find the part number for the mating connector if you need it. I think the +/- 1 uV drift with the 10 V output and the 3458A are within specs for both the 732A and 3458A. Not sure what to think about the drift on the other readings unless there is some sort of 'dirt' on the 1 V and 1.018 V binding posts and/or ground. Good luck. Joe -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Todd Micallef Sent: Saturday, August 23, 2014 4:13 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A drift Randy, I looked at the 3458a input impedance, and it is difficult to get the meter set to the FixedZ (10M) mode. However, the 100v range is 10M. It should default to HiZ on reset. I forgot to mention to check the outputs and guard resistance to ground. One of my 732a had some foam baffling under the cover that had dry rotted. There was a lot of leakage to ground. I can't remember if the foam was on the older or newer versions of the 732a. The cal light comes on with a short wire stuck in the hole and connected to a LO output terminal. I don't know, but maybe the battery charge led has to be off. Todd Sent from my iPad On Aug 23, 2014, at 1:16, Randy Evans randyevans2...@gmail.com wrote: I hope someone can help with a strange anomaly on either my 3458A or the 732A. The 732A 10V output as measured on my 3458A seems relatively stable over time (it bounces around about +/-1 uV but is it the 732 or the 3458?). However, the 1.000 VDC output drifts downward at a rate around 1-2 uV per second as soon as I plug the 3458A into the 732 output. If I remove the 3458A and connect it back up after a few 10s of seconds, the reading goes back to what it started at and then drifts downward again. The 1.018V output also drifts downward but at a much slower rate and not as much. Now the question is: is it the 732 or the 3458A? I tried to see it on my Agilent 34401A DMM but it really doesn't have the resolution, but I do seem to see it on the 1.000VDC output. If it is the 732A, what would cause it to drift downward like that? Since the 3458A has an input impedance of 10Gohm on the 1 and 10 V ranges, I wouldn't think the 732 would even see the difference of whether the 3458A is connected of not, but it clearly makes a difference as to how long its connected and how long it's been disconnected. Any one have any conjectures? Also, what will turn on the In Cal light? What does it mean if it doesn't come on? Thanks, 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 drift
Never mind. I tested it myself. You should be able to get the in cal led working without batteries. Todd On Sat, Aug 23, 2014 at 7:20 AM, Todd Micallef tmical...@gmail.com wrote: The output impedance of both the 1v outputs is ~1k ohm. I wonder if Randy could check the 3458a input impedance with a 10M ohm resistor and the 10v output of the 732a. I was thinking that the 732a needed a minimum battery voltage to allow the in cal led to turn on with the short to the Lo terminal. I guess I could try it on one of mine that is waiting for repair. Todd Sent from my iPad On Aug 23, 2014, at 6:42, J. L. Trantham jlt...@att.net wrote: Randy, The 'IN CAL' LED is turned on as Todd describes. It goes off if power to the unit is lost and, thus, calibration is lost. It is not related to the battery charge LED. As I understand it, the units are designed to powered on 24/7/365 and are 'IN CAL' once they are powered up, stable (weeks, months?), and have been calibrated by your reference lab. Once power is lost, meaning lost AC and batteries depleted, the 'IN CAL' light goes out and outputs are thereafter unreliable. Once you decide to get the 732A calibrated, you will need to find a way to ship it to the reference lab and get it shipped back while continuously powered, connecting an external battery pack to the connector on the back of the battery pack. The internal battery pack is likely to last only a few hours. There are at least two types of connectors for an external battery, two 5 way binding posts and a Hypertronics connector which is a small black connector about 'dime' sized. I can find the part number for the mating connector if you need it. I think the +/- 1 uV drift with the 10 V output and the 3458A are within specs for both the 732A and 3458A. Not sure what to think about the drift on the other readings unless there is some sort of 'dirt' on the 1 V and 1.018 V binding posts and/or ground. Good luck. Joe -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Todd Micallef Sent: Saturday, August 23, 2014 4:13 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A drift Randy, I looked at the 3458a input impedance, and it is difficult to get the meter set to the FixedZ (10M) mode. However, the 100v range is 10M. It should default to HiZ on reset. I forgot to mention to check the outputs and guard resistance to ground. One of my 732a had some foam baffling under the cover that had dry rotted. There was a lot of leakage to ground. I can't remember if the foam was on the older or newer versions of the 732a. The cal light comes on with a short wire stuck in the hole and connected to a LO output terminal. I don't know, but maybe the battery charge led has to be off. Todd Sent from my iPad On Aug 23, 2014, at 1:16, Randy Evans randyevans2...@gmail.com wrote: I hope someone can help with a strange anomaly on either my 3458A or the 732A. The 732A 10V output as measured on my 3458A seems relatively stable over time (it bounces around about +/-1 uV but is it the 732 or the 3458?). However, the 1.000 VDC output drifts downward at a rate around 1-2 uV per second as soon as I plug the 3458A into the 732 output. If I remove the 3458A and connect it back up after a few 10s of seconds, the reading goes back to what it started at and then drifts downward again. The 1.018V output also drifts downward but at a much slower rate and not as much. Now the question is: is it the 732 or the 3458A? I tried to see it on my Agilent 34401A DMM but it really doesn't have the resolution, but I do seem to see it on the 1.000VDC output. If it is the 732A, what would cause it to drift downward like that? Since the 3458A has an input impedance of 10Gohm on the 1 and 10 V ranges, I wouldn't think the 732 would even see the difference of whether the 3458A is connected of not, but it clearly makes a difference as to how long its connected and how long it's been disconnected. Any one have any conjectures? Also, what will turn on the In Cal light? What does it mean if it doesn't come on? Thanks, 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
Re: [volt-nuts] 732A drift
I think the 'IN CAL' LED has to do with a 'minimum voltage' but I don't think it has to with a minimum battery voltage. When you remove the battery pack, with the unit plugged in, I don't think the 'IN CAL' LED goes out. Otherwise, you would never be able to swap battery packs. Joe -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Todd Micallef Sent: Saturday, August 23, 2014 6:21 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A drift The output impedance of both the 1v outputs is ~1k ohm. I wonder if Randy could check the 3458a input impedance with a 10M ohm resistor and the 10v output of the 732a. I was thinking that the 732a needed a minimum battery voltage to allow the in cal led to turn on with the short to the Lo terminal. I guess I could try it on one of mine that is waiting for repair. Todd Sent from my iPad On Aug 23, 2014, at 6:42, J. L. Trantham jlt...@att.net wrote: Randy, The 'IN CAL' LED is turned on as Todd describes. It goes off if power to the unit is lost and, thus, calibration is lost. It is not related to the battery charge LED. As I understand it, the units are designed to powered on 24/7/365 and are 'IN CAL' once they are powered up, stable (weeks, months?), and have been calibrated by your reference lab. Once power is lost, meaning lost AC and batteries depleted, the 'IN CAL' light goes out and outputs are thereafter unreliable. Once you decide to get the 732A calibrated, you will need to find a way to ship it to the reference lab and get it shipped back while continuously powered, connecting an external battery pack to the connector on the back of the battery pack. The internal battery pack is likely to last only a few hours. There are at least two types of connectors for an external battery, two 5 way binding posts and a Hypertronics connector which is a small black connector about 'dime' sized. I can find the part number for the mating connector if you need it. I think the +/- 1 uV drift with the 10 V output and the 3458A are within specs for both the 732A and 3458A. Not sure what to think about the drift on the other readings unless there is some sort of 'dirt' on the 1 V and 1.018 V binding posts and/or ground. Good luck. Joe -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Todd Micallef Sent: Saturday, August 23, 2014 4:13 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A drift Randy, I looked at the 3458a input impedance, and it is difficult to get the meter set to the FixedZ (10M) mode. However, the 100v range is 10M. It should default to HiZ on reset. I forgot to mention to check the outputs and guard resistance to ground. One of my 732a had some foam baffling under the cover that had dry rotted. There was a lot of leakage to ground. I can't remember if the foam was on the older or newer versions of the 732a. The cal light comes on with a short wire stuck in the hole and connected to a LO output terminal. I don't know, but maybe the battery charge led has to be off. Todd Sent from my iPad On Aug 23, 2014, at 1:16, Randy Evans randyevans2...@gmail.com wrote: I hope someone can help with a strange anomaly on either my 3458A or the 732A. The 732A 10V output as measured on my 3458A seems relatively stable over time (it bounces around about +/-1 uV but is it the 732 or the 3458?). However, the 1.000 VDC output drifts downward at a rate around 1-2 uV per second as soon as I plug the 3458A into the 732 output. If I remove the 3458A and connect it back up after a few 10s of seconds, the reading goes back to what it started at and then drifts downward again. The 1.018V output also drifts downward but at a much slower rate and not as much. Now the question is: is it the 732 or the 3458A? I tried to see it on my Agilent 34401A DMM but it really doesn't have the resolution, but I do seem to see it on the 1.000VDC output. If it is the 732A, what would cause it to drift downward like that? Since the 3458A has an input impedance of 10Gohm on the 1 and 10 V ranges, I wouldn't think the 732 would even see the difference of whether the 3458A is connected of not, but it clearly makes a difference as to how long its connected and how long it's been disconnected. Any one have any conjectures? Also, what will turn on the In Cal light? What does it mean if it doesn't come on? Thanks, 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
[volt-nuts] 732A drift
I hope someone can help with a strange anomaly on either my 3458A or the 732A. The 732A 10V output as measured on my 3458A seems relatively stable over time (it bounces around about +/-1 uV but is it the 732 or the 3458?). However, the 1.000 VDC output drifts downward at a rate around 1-2 uV per second as soon as I plug the 3458A into the 732 output. If I remove the 3458A and connect it back up after a few 10s of seconds, the reading goes back to what it started at and then drifts downward again. The 1.018V output also drifts downward but at a much slower rate and not as much. Now the question is: is it the 732 or the 3458A? I tried to see it on my Agilent 34401A DMM but it really doesn't have the resolution, but I do seem to see it on the 1.000VDC output. If it is the 732A, what would cause it to drift downward like that? Since the 3458A has an input impedance of 10Gohm on the 1 and 10 V ranges, I wouldn't think the 732 would even see the difference of whether the 3458A is connected of not, but it clearly makes a difference as to how long its connected and how long it's been disconnected. Any one have any conjectures? Also, what will turn on the In Cal light? What does it mean if it doesn't come on? Thanks, 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.
