Empathy List Archives

DC

David C. Partridge

Wed, Jan 10, 2018 10:13 AM

After running an ACAL 0 with a four wire short in place I get a DCV reading
starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV
over a minute or so at which point it seems to stabilise.

Is this "normal" and if not what could be wrong (AZERO is turned on).

Dave

After running an ACAL 0 with a four wire short in place I get a DCV reading starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV over a minute or so at which point it seems to stabilise. Is this "normal" and if not what could be wrong (AZERO is turned on). Dave

PK

Poul-Henning Kamp

Wed, Jan 10, 2018 10:23 AM

In message 003801d389fb$bbba1f10$332e5d30$@perdrix.co.uk, "David C. Partridge
" writes:

After running an ACAL 0 with a four wire short in place I get a DCV reading
starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV
over a minute or so at which point it seems to stabilise.

That is pretty normal, it's very hard to control temperatures so precisely
that you don't get a few hundred nanovolts of seebeck voltage.

If you touch the short with your finger, you will change the temperature
enough that it registers clearly.

I mount the short, then hang a piece of cloth over the terminals and wait
about 15-30 minutes before I run ACAL 0

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

-------- In message <003801d389fb$bbba1f10$332e5d30$@perdrix.co.uk>, "David C. Partridge " writes: >After running an ACAL 0 with a four wire short in place I get a DCV reading >starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV >over a minute or so at which point it seems to stabilise. That is pretty normal, it's very hard to control temperatures so precisely that you don't get a few hundred nanovolts of seebeck voltage. If you touch the short with your finger, you will change the temperature enough that it registers clearly. I mount the short, then hang a piece of cloth over the terminals and wait about 15-30 minutes before I run ACAL 0 -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

DC

David C. Partridge

Wed, Jan 10, 2018 10:25 AM

Correction to -0.00060mV to -0.00070mV

Dave

-----Original Message-----
From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of David C. Partridge
Sent: 10 January 2018 10:14
To: 'Discussion of precise voltage measurement'
Subject: [volt-nuts] 3458A question

After running an ACAL 0 with a four wire short in place I get a DCV reading starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV over a minute or so at which point it seems to stabilise.

Is this "normal" and if not what could be wrong (AZERO is turned on).

Dave

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.

Correction to -0.00060mV to -0.00070mV Dave -----Original Message----- From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of David C. Partridge Sent: 10 January 2018 10:14 To: 'Discussion of precise voltage measurement' Subject: [volt-nuts] 3458A question After running an ACAL 0 with a four wire short in place I get a DCV reading starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV over a minute or so at which point it seems to stabilise. Is this "normal" and if not what could be wrong (AZERO is turned on). Dave _______________________________________________ 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.

DC

David C. Partridge

Thu, Jan 11, 2018 1:56 PM

To add some more information

The meter has now been on for a number of days with a newly cleaned 4 wire short in place all the time.

I have run a full CAL 0 to zero the offsets, but even so, and after running an ACAL 0, I get a DCV reading of -200 to -400nV (0.00040mV).

Is that normal? I'd have thought it would typically be less than that given that the 1 year limit is 0.00106mV (1.06Uv).

Thanks again
David

-----Original Message-----
From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of David C. Partridge
Sent: 10 January 2018 10:25
To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] 3458A question

Correction to -0.00060mV to -0.00070mV

Dave

-----Original Message-----
From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of David C. Partridge
Sent: 10 January 2018 10:14
To: 'Discussion of precise voltage measurement'
Subject: [volt-nuts] 3458A question

After running an ACAL 0 with a four wire short in place I get a DCV reading starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV over a minute or so at which point it seems to stabilise.

Is this "normal" and if not what could be wrong (AZERO is turned on).

Dave

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.

To add some more information The meter has now been on for a number of days with a newly cleaned 4 wire short in place all the time. I have run a full CAL 0 to zero the offsets, but even so, and after running an ACAL 0, I get a DCV reading of -200 to -400nV (0.00040mV). Is that normal? I'd have thought it would typically be less than that given that the 1 year limit is 0.00106mV (1.06Uv). Thanks again David -----Original Message----- From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of David C. Partridge Sent: 10 January 2018 10:25 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] 3458A question Correction to -0.00060mV to -0.00070mV Dave -----Original Message----- From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of David C. Partridge Sent: 10 January 2018 10:14 To: 'Discussion of precise voltage measurement' Subject: [volt-nuts] 3458A question After running an ACAL 0 with a four wire short in place I get a DCV reading starting at about -0.00005 mV to increasing to about 0.00060 to 0.00070 mV over a minute or so at which point it seems to stabilise. Is this "normal" and if not what could be wrong (AZERO is turned on). Dave _______________________________________________ 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.

PK

Poul-Henning Kamp

Thu, Jan 11, 2018 2:50 PM

In message 000001d38ae3$ea81a2d0$bf84e870$@perdrix.co.uk, "David C. Partridge
" writes:

The meter has now been on for a number of days with a newly cleaned 4 wire short in place all the time.

I have run a full CAL 0 to zero the offsets, but even so, and after running an ACAL 0, I get a DCV reading of -200 to -400nV (0.00040mV).

Is that normal?

I see the same kind of numbers.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

-------- In message <000001d38ae3$ea81a2d0$bf84e870$@perdrix.co.uk>, "David C. Partridge " writes: >The meter has now been on for a number of days with a newly cleaned 4 wire short in place all the time. > >I have run a full CAL 0 to zero the offsets, but even so, and after running an ACAL 0, I get a DCV reading of -200 to -400nV (0.00040mV). > >Is that normal? I see the same kind of numbers. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

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3458A question