You know, I worked on tracing that hum for the past two days and could not find it. The only thing I noticed was when I unplugged the power cord feeding the laptop it would go away, plug it back in...hummmmmmmmmmmmmmmmmmmmmm. After reading InterpreDemon's post about the Yagi I decided to do a real quick antenna change, since I just happened to have a Arrow Yagi in the radio room. I took down the J-Pole, put up the Yagi, secured the coax, headed back in the radio room to check on my results and the first thing I noticed is the levels on the OddATC meters have dropped to almost nothing.... meaning the hum is gone! Where it went, I haven't a clue, and I really don't care as long as it never comes back. I did notice that reception, in my opinion, is much better. The controller on 128.575 is still not full quieting, but much better, and like JetScan1 stated, 132.15 is 5x5. Also, 123.625 has gotten stronger. I do not know where that transmitter is, but is has to be to the east of me somewhere.
Interesting that the controller on 132.15 is noticeably stronger than the controllers on the other frequencies. I believe they are all transmitting from the same North Mountain location ? Except 124.900 and 127.725 that are from the Williamsport site ?
I also find this interesting. The only thing I can figure is that possibly the antenna for 132.15 is at the top of the tower and the antenna for 128.575 hung mid-tower or lower. I don't know, just a guess.