KC7SDA USB power supply emissions

[Robert Sears]

I know a few of you have bought Art Millers kit for a USB power supply. I had some spare time today and ran it through a radiated emissions test. You will be happy to know that this would pass FCC class B. The plot shown only covers about 30Mhz to 400 Mhz since the switcher runs at 42Mhz there was no sense measuring any lower.  Remember the enclosure construction techniques can change these results.

X scale is frequency Y is dbmv measured at 3 meters.

[Art]

I'll bring a couple wall wart usb chargers to the next meeting, i'm curious as to how they would stack up to this

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