[mikets]

Before you cut the wire, plug the AC adapter to the wall, use the voltmeter to check the voltage between the center of the barrel and the outside of the barrel. It should be about 5V and note the polarity. The center should be positive and the outside should be negative. After you cut the cable and splice it to the DC-DC converter. Do the same check on the connector to make sure it is still 5V and the polarity is the same as you have noted before. Then you can plug the power into the radio.