850 Wagon AM Static

[walt007]

I have intermittent AM static on my '95 850 wagon. Other than that, AM reception is fine.
Clues:
1) Vehicle-speed related, not engine-RPM related.
2) Present when coasting.
3) Goes away when I apply the brakes and then starts up again getting louder with time. I also note a reduction when the hand brake is slightly applied.
4) Is not evident on damp days.
Could it be electrical-static buidlup or related to the ABS brake system.?