Also you could call the radio station. They are usually very interested in preventing what is happening to you - its in their license - they are not supposed to cause interference. So they might be willing to send someone out to help you.

You didn't say whether station was AM or FM. If FM you could use ferrite beads sprinkled around on your cables where thay enter equipment. If AM its more likely grounding. Whole system should have a common ground and that one actually grounded (cold water pipe?)at only one point.

I know this is late, but I just noticed your cry for help. Hope these hints may help you or others.
-Dicck