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 <[email protected]> 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" <[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.
