Ground runs can possibly solve this problem, unfortunately you will have to experiment for yourself. Begin with the tonearm to phono stage, add a ground, or if it already exists, remove it and listen. Run a ground between the preamp and phono, without the turntable ground, and with. If any equipment, especially the turntable or phono stage are sitting on ANY type of metal stand or rack, run a ground from the rack to a true ground. I cannot promise any of this will solve the problem, but it is only an exercise in labor, with a small investment in some ground wire. I sincerely hope one of these suggestions will bleed off your unwanted radio reception.