Re: Getting calibration equipment calibrated


Stephen Hanselman
 

Walter,

I second your comments. We had a “cal-light” lab. Two GPSDO’s and a HP3458 and a set of Julie labs precision resistors. The 3458 got the stds lab cal at keysight ($1800) and then everything was aligned to that unit.

Our customers did not consider us a cal lab but a repair station. They were required to use specific labs which caused problems. We received MANY pieces of equipment that “didn’t pass cal” that merely required doing the entire calibration procedure carefully. Even with our loose definition of “cal to zero” we never had a unit rejected by the same lab that failed it originally.

Be careful with who you choose for your cal facility, there are a few good ones and many “Lick and Stick” operations.

Regards,

Stephen Hanselman
Datagate Systems, LLC

On May 24, 2021, at 07:58, walter shawlee <walter2@sphere.bc.ca> wrote:

Outside calibration is complex situation, especially since it is understood differently by the
providers of the service, and their customers. this disconnect can be severe, and often leads to
some significant unhappiness on the part of equipment owners.

I documents all olf this in detail when I was writing for the AEA (Aircraft Electronics Association),
you can grab those articles HERE on our site:
https://www.sphere.bc.ca/test/data.html

look halfway down the left hand yellow area where you see the AEA logo. "understanding calibration"
be aware that you will likely get your gear back just as you sent it, with no improvement at all.

I love metrology, and the whole idea of chasing precision to wind up with things as accurate as possible.
I have a GPS, three rubidium standards, and three high end OCXOs I cross check just to get a clean
known 10.000000Mhz value for doing counter calibration. This path is NOT for everyone, and no single standard,
without regular external validation is of any value in the calibration world. Every lab should have some known
references as a sanity check, even if it's just a few precision resistors and known frequency. Known DC voltage
can be harder, and known AC voltage harder still.

One of my best friends runs a metrology lab here, and I watch what he has to go through each year to
have traceable accredited standards, it is not for the faint of heart. I am eternally grateful he helps me
with my cals, or I could never really be sure of anything.

all the best,
walter

--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca
+We're all in one boat, no matter how it looks to you. (WS2)
+All you need is love. (John Lennon)
+But, that doesn't mean other things don't come in handy. (WS2)
+Nature is trying very hard to make us succeed, but nature does not depend on us.
We are not the only experiment. (R. Buckminster Fuller)





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