And don't forget it can be battery operated devices, like laptops, iPods, CD players, etc.
Something is getting turned on and you need to play detective. I once had to investigate a "line noise" issue that turned out to be the owner's new DVD player. Chuck WB2EDV An old trick - if the on-time changes about 6 minutes a day then it's light-dependent (i..e a photo-electric triggered yard light). In your shoes I'd power the radio from a gell-cell, and then go flip breakers off one at a time. That will tell you if the noise source is inside the house, and if so, on which breaker. Mike WA6ILQ
