Doug, Your once-a-year lab bashing is offensive, some years you do it more and honestly I'm tired of not saying something about it. It's especially offensive to people like myself whom has been running test labs for the last 33 years and pride myself in the work we have provided to our customers over that time.
I could put up posts about bad EMC consultants that have been at our laboratory and provided expensive misguided information to our customers, or no solution at all to their EMC issues, however I choose not to stoop to your level. Categorizing test labs based on your limited experience (my guess is you've only been to a few labs, compared to how many there are in the USA and abroad) to make yourself look good continues to be ridiculously petty. You could certainly word this in a different way that doesn't generalize how "most" test labs are bad and/or incompetent. How about in the future you find a different way to word things. Larry K. Stillings Compliance Worldwide, Inc. Test Locally, Sell Globally and Launch Your Products Around the World! 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From: doug emcesd.com Sent: Thursday, August 10, 2023 7:34 PM To: [email protected] Subject: [PSES] thoughts on ESD test lab problems Hi All, Just a couple of thoughts on what a good lab should do for ESD testing and how to protect yourself as a client from test problems. 1. Bring an Ohmmeter with you to the lab and measure the resistance from the Horizontal Coupling Plane to the Ground Reference Plane. It should be about 2X 470 K. I have seen both commercial test labs and private labs where these resistors are open which can cause a product failure. A good lab should measure this value every morning and report the result in your test report.. 2. The vacuum relay in the ESD simulators have a limited life after which the current waveform becomes quite variable and at that point cannot give an accurate test of your equipment. Having a valid calibration sticker is close to useless as the condition can develop quickly. I have personally seen a rented simulator with a valid calibration sticker have this problem with its current waveform all over the place from one discharge to another. A good test lab will verify this is not happening at the beginning of each day. You as a client can tell from a distance by just making a small antenna by extending a coax center conductor 6 inches pass the shield to make a small antenna. Better would be to make a TEM antenna which does not color its output by its resonances. Connect the antenna to a scope of at least 4 GSa/sec sampling rate, preferably higher. You don't really care what waveform you get, say from 6 feet away, but each discharge of a series of ten should look the same. More to come! Most test labs I have used over the years made at least one mistake that affected the test results. I have had disagreements with labs, never lost one of them. Doug [https://lh4.googleusercontent.com/_HuR3Ky2TF_XhFHyxnYRmiq7nHQldnMsPNYFaLG6kb5T4y8MeCe-BDC_BscJtSFgszSSjssihHS-pjM3-jwNP8S0CwE-gN8fsRsPkojiAlmpBwb20vIVizS-siCUywW_jqrefbVr] ________________________________ This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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