[RFI] Noise - where do I start?

[dalej]

Most likely power line if it’s raspy/buzzie and you can get a beam heading on it on the 10 meter band.  Once that a general direction is found then walk the power line with an aircraft band receiver, 126 Mhz or so in AM mode.  You will be able to get close with it.  Take binoculars along and visual the power poles in the suspect area.  I have found rotten pole tops with loose hardware.  Sometimes at night even seen the arcs.  After you are sure of the general location then it’s time to call the power company and go along with the noise tech, work together.  

That’s my two cents worth.

Dale, K9VUJ