There is no reason for a phono system to act as an antenna, even with a MM cartridge, with the possible exception that you live near or under a transmission tower, if you will:
1.) Make sure the turntable, tonearm, and phono preamp (if separate) are properly grounded to the rest of the system. If the separate phono preamp has a three prong plug, use a lifter (or "cheater plug") to disable the ground -- it gets its "ground" from the main preamp through the IC's.
2.) Use shielded IC's from the phono preamp to the preamp (and throughout your system, preferably) making sure the IC's have a "floating shield" (one that's connected to ground at only one end, usually the "arrowhead" end) and make sure the arrowhead end is at the preamp.
3.) Oh yes, and make sure the main preamp IS grounded at the wall!
That should do it.
.
1.) Make sure the turntable, tonearm, and phono preamp (if separate) are properly grounded to the rest of the system. If the separate phono preamp has a three prong plug, use a lifter (or "cheater plug") to disable the ground -- it gets its "ground" from the main preamp through the IC's.
2.) Use shielded IC's from the phono preamp to the preamp (and throughout your system, preferably) making sure the IC's have a "floating shield" (one that's connected to ground at only one end, usually the "arrowhead" end) and make sure the arrowhead end is at the preamp.
3.) Oh yes, and make sure the main preamp IS grounded at the wall!
That should do it.
.