Condenser Mic Interference?

A while back I bought a Nady CM-88 condenser mic so I could record with my band. I bought the mic, and I kept picking up a radio station. Since my uncle seemed more than happy to give me this phantom power supply, I figured that the power supply was giving me interference. The other day I got another condenser mic, and hooked it up to the phantom power. No interference. As soon as I plugged the CM-88 in, I picked up the radio station. Is there any way I can get rid of, or at least damper the interference so I don't hear mariachi music on every ******* recording? Anything helps at this point.