Press and hold the 1 and 6 radio preset buttons, and turn ON the device. The display toggles between two screens: U with the first 4 digits of the serial number (U2200 for example,) And L with the last 4 digits of the serial number (L0055 for example.) Ignore the U and L and record all 8 digits.
brettg - 12/1/2016 11:15 I've got a portable one with an fm modulator and a lifetime membership too - it works great. It's in the car every day when I go to work, and in whatever piece of machinery I happen to be running at night and on weekends. I just move the radio from vehicle to vehicle - it's about the size of a cellphone. The chargers and antennas are cheap, so I have one set for each vehicle and one set that I move around between the farm equipment. It's hard to get radio stations to come in with some of our old tractor radios - and I'm not a huge fan of any of our local stations anyway. With the xm, I can listen to old country and baseball no matter how weak the antenna in the tractor is, or how far out in the boonies I am. The thing that always gets me is - xm radios are proof that satellite phones would work exponentially better than the cell phones we all carry around - but there aren't enough of us out here in the country to make it worthwhile for the companies to develop them.