first off, the method Beetle posted is the way to find out if there is interference coming from inside your home.
my guess is that the interference is coming from an outside source.
first question, have you had a base station antenna up at this location previously?
how long ago?
what were the differences in the two antenna setups?
second question, does this interference seem stronger on some channels than others?
third, is there EVER a time when the interference is not there?
i know you said that watering your ground system eliminated the interference for a short while.
is there any chance that it was just a coincidence and the noise just happened to be gone when you tested the radio?
most likely, your interference is coming from one of your neighbors' houses.
wireless mouses, wireless keyboards, bug zappers, faulty wall wart adapters, and touch lamps are all well known causes of interference.
it could also be a transformer on a power line is faulty and causing the interference.
i used to get horrible interference, but noticed that it went away after about 11pm.
turns out it was the outback steakhouse up the street and their paging system for letting you know when your table was ready.
let us know what you find,
LC
