Calibration certificate for Keithley 2002

[nikonoid]

Today I got my Keithely 2002 meter back from calibration by a local A2LA accredited lab. Calibration was supposed to be done on Fluke 5720A.

I was told that my meter is in calibration, no adjustments needed and got a passing certificate with data. Few data points were right at the 1yr spec for the instrument. Is it usual for a cal lab not to adjust something that is right on the edge?

AC checks were done at 1KHz only. Is that usual?

Should I be expecting instrument to be in a better shape than 1 year limits since 1 year limit includes +/-5 C temperature fluctuation and at cal lab there should not be such a fluctuation?

Can someone publicly or privately (PM) please share their cal certificate for Keithley 2001 or  2002?

Thank you very much.

[alm]

I was told that my meter is in calibration, no adjustments needed and got a passing certificate with data. Few data points were right at the 1yr spec for the instrument. Is it usual for a cal lab not to adjust something that is right on the edge?

Depends on the type of calibration. Keysight offers guardbanding as an option (i.e. if the reading is closer to the limit than the measurement uncertainty, it is adjusted/rejected). This paper discusses it in some detail.

AC checks were done at 1KHz only. Is that usual?

I do not have the Keithley 2002 calibration procedure in front of me, but I am pretty sure it includes points up to a few hundred kHz. So I would say no.

Should I be expecting instrument to be in a better shape than 1 year limits since 1 year limit includes +/-5 C temperature fluctuation and at cal lab there should not be such a fluctuation?

If you have no history on the unit, then I do not see why it could not be at the edge of its 1 year limits. If it was calibrated a year ago, then I would compare the data between calibrations.

[nikonoid]

This meter was repaired by me, and then I calibrated it myself against a calibrated 6.5 digit meter, just to prove to myself that calibration function works. I have no history for the instrument and was hoping that the lab would calibrate it to correspond to their calibrator, instead of just measuring few values.

I did said to the lab, that the meter was repaired, please adjust. Should I have said something different. I am a bit new here.


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[Macbeth]

Did you pay for the adjustment and they didn't do it? I would be mad too, especially as this is a repaired unit and has no history - do a full factory reset and adjustment.

Also why not post your cal data with appropriate redactions before asking others to post theirs? "You show me yours and I'll show you mine!" 

[nikonoid]

Also why not post your cal data with appropriate redactions before asking others to post theirs? "You show me yours and I'll show you mine!" 

Good point. Redacted certs are attached. Getting 2002 calibrated for the first time I was not sure what to expect from a certificate. Let me know what you think, especially Ohms section. 

[TiN]

That is interesting "calibration report". It's more like a lab note of quick check, than by any means calibration report.
No zero check, meter tested only at 1/2 of the scale, messed up resistance check (100 ohm at 20 ohm range?  ) without again any zero data.
No standards value for resistance? As you already saw, only single 1kHz frequency test for ACV. You can check calibration manual for 2002, which does list very well defined performance test procedure.

Minimum required 2002 equipment list for performance test is 4W banana short, F57x0 + booster F5725 + 1Gohm resistance standard + AFG to test frequency.
Minimum required 2002 user calibration list: F57x0 (booster is not required)
Minimum required 2002 manufacturing calibration list: F57x0 (booster is not required) + stable AC source to supply 1Hz 2V signal + GPIB software.

Also you may want to have ambient temperature at +24 C, instead of +20 C for a meter like 2002, guessing that you might likely to have 24-25C ambient, than keeping it that chilly for days.

But all these are not the first question you should ask. Correct question is - what level of accuracy do you need/want/can afford. Based on response, you have various option then, from cheap 3rd tier lab calibration (which is not including adjustment, that's what you got now) to Keithley/Tektonix calibration(+adjustment if desired) for which you likely be required to send unit to Keithley USA, or to 1st tier calibration from top dogs for lot of $$$$.

After full service cal + adjustment it's reasonable to expect meter to meet it's 24 hour specification, not 1 year!

I've attached calibration report from one of K2001 I've adjusted and tested for your reference.

[CalMachine]

The lab that performed this calibration might be A2LA accredited, but this is definitely not an accredited calibration.  Not adjusting a meter, that is found to be within OEM/Customer specifications, is common practice in the lower echelon of calibration providers.  Especially when it is just a NIST traceable cal. 

If you would like a cheaper option than Keysight, I would be more than happy to make the adjustments for you.

[RandallMcRee]

Seems like a great offer, CalMachine.

On the sunny side (is that a Californian expression?) it seems like you did a good job calibrating it initially, nikonoid. Given that you had, what? a 6.5 digit uncalibrated meter at hand?

Randy
(But its foggy here on west coast, just FYI)

[nikonoid]

TiN, yes I like your certificate much better than mine  .

This is the most comprehensive I have ever seen. Can someone share a sample calibration certificate from a good US lab, so we can see how they compare to TiN?


As the temperature is concerned, it does not bother me too much, as I usually operate at 22C +/-1.

I am curious who is the top tier of calibration labs (top dogs  )?

I called Keysight@Loveland and the pricing seemed very reasonable and included adjustments and before/after data with  Z540 certificate. Is Keysight expected to do good job on Keithleys?

CalMachine, thank you for the offer. I am sure your attention to detail would be second to none, not like the local lab. I will PM you.

But first of all I will pay a visit to local lab and demand either re-calibration or money back. I so wanted to like them, they are only 5 minutes away.

On the sunny side (is that a Californian expression?) it seems like you did a good job calibrating it initially, nikonoid. Given that you had, what? a 6.5 digit uncalibrated meter at hand?

Thank you, Randy. I used a Keithley 2000, calibrated 2.5 years ago and is still going strong. I am also impressed with my Dial-A-Volt standards (3 of them). I bought them all broken for nothing, fixed them and they had been running +/- 2PPM from the Keithley for a while. Recently I did a 2 weeks non stop run and they are only fluctuating by +/- .5 PPM.

 

[TiN]

I see no reason why KS Lab would have any issue with Keithley meters. After all it's all same stuff, just different buttons

Here's my old 2001 certificate, from Tektronix Taiwan lab. Not very great, but I had nothing better back then. Paid 550$ for that one (Z540 w/data).

And here's example 2002 cert from same lab. Not mine unit, they sent me this cert as example when I was asking about 2002 cal, however that needed shipping to USA lab, so I didn't do it.

Top tier labs are national level institutions (NIST, PTB, NMI etc) and manufacturer standards labs who maintain best accuracy (Keysight Loveland Standards lab, Fluke Everett lab, etc). Calibration for few voltage points from NIST would cost more than brand new 2002 .

as I usually operate at 22C +/-1.

Jealous...

[EEVblog]

Today I got my Keithely 2002 meter back from calibration by a local A2LA accredited lab. Calibration was supposed to be done on Fluke 5720A.
I was told that my meter is in calibration, no adjustments needed and got a passing certificate with data. Few data points were right at the 1yr spec for the instrument. Is it usual for a cal lab not to adjust something that is right on the edge?

When you send an instrument in for "calibration" that usually implies a "calibration check" and not "calibration adjustment". A good cal lab would not adjust anything without your approval.

[alm]

That is not what Keysight does by default. See attachment or this link.

See this document about their acceptable limits and when they adjust with which service.

[nikonoid]

Thank you, TiN, Dave and Alm. This is super useful.