[volt-nuts] DMM calibration

Thu Aug 8 13:58:40 EDT 2013

You will find that most old "stuff" does not drift as much as the new
"stuff".
Most resistors seem to drift in a damped sine wave rate with a period of
about 4 years.

On Thu, Aug 8, 2013 at 10:10 AM, Didier Juges <shalimr9 at gmail.com> wrote:

> I had my eBay special $90 HP3478A calibrated by our internal cal lab
> (traceable to NIST). Based on the sticker, the last cal was 5 years old.
> The instrument was well within all specs by a wide margin (most readings
> were within 20% of the stated tolerance, which after 5 years is pretty good.
>
> Didier KO4BB
>
> Roy Phillips <phill.r1 at btinternet.com> wrote:
> >
> >
> >-----Original Message-----
> >From: Electronics and Books
> >Sent: Thursday, August 08, 2013 12:54 PM
> >To: Discussion of precise voltage measurement
> >Subject: Re: [volt-nuts] DMM calibration
> >
> >Specs for a 3478A
> >
> >
> >Brand HP Model 3478A Counts 303.099 TrueRMS X Display LCD  Year 1983
> >Range
> >Stability [ppm] Low   High   Resolution      1y
> >DC Volt 30m  300  100n 60 AC Volt 300m 300  1u  2000 Max Frequency 300k
> >
> >Resistance 30  30M  100u 160 DC Current 300m 3  1u  1500 AC Current
> >300m 3
> >1u  7200 Interface GPIB Battery backup X
> >If you do the adjustments with some hobby equipment wich an accuracy of
> >say
> >20 to 30 ppm. Thats all within limits of this multimeter. You never see
> >the
> >difference.
> >In my opion, expensive adjustments and calibration for not so accurate
> >equipment is a waste of money. Especialy when the calibration price
> >exceeds
> >the equipment price.
> >
> >
> >
> >
> >
> >Regards
> >
> >
> >ElectronicsAndBooks at Yahoo.com
> >http://ElectronicsAndBooks.com
> >
> >I would like to say - "you are absolutely correct" - I have recently
> >been
> >quoted for a 3458A which requires a new set of ROM's and re-cal. - the
> >cost
> >was greater than I paid for the S/H instrument just 4 years ago. These
> >prices are OK for large Companies who can recover the VAT for a start !
> >
> >......... but cannot be justified for hobbyists. Most of us have items
> >of
> >equipment that have been calibrated in recent times, and other
> >precision
> >items like resistors and higher spec. zeners that when you make
> >comparisons
> >can verify your DVM's . I recently purchased a Keithley 2015 for less
> >than
> >some cal. charges, this was calibrated in 2008 and I would say that it
> >is
> >still in very good calibration now.
> >Roy P
> >
> >
> >________________________________
> >From: "Marv @ Home" <marvin.gozum at comcast.net>
> >To: Discussion of precise voltage measurement <volt-nuts at febo.com>;
> >Discussion of precise voltage measurement <volt-nuts at febo.com>
> >Sent: Wednesday, August 7, 2013 6:53 PM
> >Subject: Re: [volt-nuts] DMM calibration
> >
> >
> >I don't know what logo cal is, but between Z540 and 17025 is a
> >question of procedures and how they are done.
> >In metrology the procedures, and how strict they are, reduce the risk
> >of uncertainty in the final measurement.  For example, some
> >procedures in Z540 can be 'interpreted' where in 17025 is explicit,
> >thus there is more room in Z540 for one lab to be worse than another,
> >or vice versa, which defeats the purpose of standardization.  This
> >'intepretation' is fairly reduced when the device is cal'd by an
> >autocalibrator such for close case calibration DMMs, but becomes a
> >big issue with any manual cal.
> >
> >If these do not mean anything to you and you do not need the data for
> >long term drift calculations, ISO 9001 is good to go.
> >
> >IMHO the difference between all 3 is insignificant for 5.5 digit
> >DMMs, except for one's need for data.
> >
> >
> >
> http://us.flukecal.com/literature/articles-and-education/temperature-calibration/papers-articles/comparison-ansincsl-z540-1?geoip=1
> >
> >At 12:30 PM 8/7/2013, Joseph Gray wrote:
> >>I just got the following quote for getting my HP 3478A calibrated.
> >>
> >>35.00 for ISO 9001 no data
> >>87.50 for Z540 with data and uncertainties
> >>275.00 for 17025 with data, uncertainties and logo calibration.
> >>
> >>I still didn't get any explaination as to exactly what the lab does
> >for
> >>each of these price points. When I asked about the "Level 4" listed
> >next to
> >>the meter, I was told that it is the difficulty level. Still not
> >telling me
> >>much. I have read the procedure in the HP service manual and it is
> >very
> >>easy. You set some volt, amp, ohm values on the standard, then push
> >some
> >>buttons on the meter.
> >>
> >>I understand about getting data or not, it is the other aspects that I
> >>don't understand. What is Z540, 17025 and "logo calibration"?
> >>
> >>
> >>Joe Gray
> >>W5JG
> >
> >
> >
> >Sincerely,
> >
> >
> >
> >Marv
> >Philadelphia, PA
> >
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> --
> Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other
> things.
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-- 
John Phillips