The power to the receiver was unplugged.
But the receiver is grounded by other wires to the rest of the house wiring.
There was about a 14V AC between the equipment ground and the distant
satellite dish ground. The run between the house and the dish is about 200 Feet.
When it’s dry, only about 10mA flows. But when it’s wet, it can get up to 100+mA between the house and the dish.
The main line that goes by the house is single phase, so there is always a voltage drop on the HV neutral that varies depending on load on the line. That voltage is imposed on all the houses that are grounded to that line. So it is normal for houses around here to have a small AC voltage between the house ground and a pole driven into the ground at a distance.