[RFI] Noise - where do I start?

[thoyer]

Haven't been active much of the summer. In the recent weeks I started
noticing a very broad band noise. 
 
Link to a video file (large). www.thdesignsinc.com/noise
 
There are times when it totally disappears but I have not spent enough
time(yet) noting when I hear it and when I don't.
 
I shut down the power in the house and only had the radio plugged in - no
difference.
 
Looking to be pointed in the right direction - power line noise or possibly
neighbors.
 
Regards, 
 
Tom
W3TA