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: [email protected] [mailto:[email protected]] 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" <[email protected]> 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: [email protected] [mailto:[email protected]] > 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 <[email protected]> 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 -- [email protected] To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. > _______________________________________________ > volt-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
