"It is grounded to Earth on a seperate rod from the house as a precaution from lighting strike"
If your ground rods are not tied together, you may have created a ground loop. The two different grounds will have slightly different potentials and will oscilate between each other causing the hum or ground loop.
You might try disconnecting the FM section of your set up and see if the hum goes away.
Dave
If your ground rods are not tied together, you may have created a ground loop. The two different grounds will have slightly different potentials and will oscilate between each other causing the hum or ground loop.
You might try disconnecting the FM section of your set up and see if the hum goes away.
Dave