[volt-nuts] 732A drift

[Todd Micallef]

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 <tmicallef at 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" <jltran at 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-bounces at febo.com [mailto:volt-nuts-bounces at 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 <randyevans2688 at 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 at 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 at 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 at febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> > and follow the instructions there.
>