Power line noise is certainly a problem, but I believe the more common source of radio noise is from *inside* our homes and offices. Here's a link to a presentation I did on this topic and ideas on tracking down the offending devices...
http://www.wd8das.net/Tracking-Radio-Noise.pdf
Steve WD8DAS
sbjohnston@aol.com
http://www.wd8das.net/
http://af4k-crystals.com
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