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FCC LISN Calibration

Quite a few years back now when I was working as an #FCC #TCB. When it came to a complicated submission, I would browse through previous submissions to give me some confidence that I had everything covered. The FCC didn’t strictly encourage this, but most TCB’s did it anyway 😊.

There are lots of test reports from EMC laboratories around the world listed on the FCC’s web access portal where a plug-in adaptor has been tested for conducted emissions on the end of a standard off the shelf 1m extension lead connecting it to the LISN. It is extremely likely that the setup used does not meet the requirements for ANSI C.63.4.

This specifies that the impedance limits for LISN’s should be met at the end of the extension lead. There is a relaxation that allows for a broader tolerance of +30% instead of +20% when using an extension, but even with this it is extremely difficult to meet the impedance requirements above 20 MHz when using a standard cord.

There is a requirement for accreditation bodies to check this when technically assessing a laboratory for an FCC accreditation submission. Here in the UK, we have an extremely diligent accreditation body… #UKAS and this is definitely something that is checked by them.

Well… The answer. It is a calibrated extension lead for FCC testing that the Equipment Calibration Business have just made for a client. The lead has a special construction that allows it to meet the impedance requirements when used with (in this case) a Rohde and Schwarz LISN. In fact, with this lead, the C63.4 limits are met even without the extended tolerance requirement.

The Equipment Calibration Business will be exhibiting at the Newbury show next year, so come along and talk to us about any calibration requirements you have. Our business model of on-site calibration where we come to you is going from strength to strength with some great feedback from the customers we currently service.

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