[RFI] Introduction - power line noise

Lee K7TJR k7tjr at msn.com
Sun Jun 24 19:24:46 PDT 2012

  Paul, I feel your pain. I have power lines close from 4 power
 generating dams within 20 miles of my house. There are many
 powerlines from 110V to 500KV.
   I concur that you need to go higher in frequency to narrow
 down your area of sweep. I have had the good fortune to ride
 with a contractor RFI locating company that contracts to our
 local power company. I am quite sure he has all the tools.
   I personally have 160,80, and 40 meter loops for mobile.
 While helpful, I seldom can actually pinpoint anything. I 
modified a 220 Mhz receiver to receive AM and found with a
 5 element beam I could pinpoint to a pole. When the contract
 guy got here he drug out a very long 6 foot or so multi
 element beam for around 500 MHz. He was actually able to
 pinpoint right down to a crossarm where the problem was. He
 would then switch to the ultrasonic and actually pinpoint right
 to the loose part.
   Not every noise can be found with these tools. There are
 many different scenarios and one I remember was a 7MHz
 problem that we could only track between 5 and 7MHz. We
 could get close but not find the problem in a newly wired cul 
de sac. At last resort I took my BC battery radio and held it
 next to every metal box in the sub-division until success. You
 could even hear the arc when you got close enough as a plug
 inside the metal box was not plugged in all the way.
  One of this contractors new tools is a 300 MHz receiver
 feeding a laptop computer with GPS. As you drive around
 it measures the interference levels and marks the map where it
 was loudest. Pretty slick, but not applicable to all really low
 frequency problems. 
   Good luck with your problem and borrow a radio with AM at
 450 MHz and a beam and I think you will do a lot better.
Lee  K7TJR  OR 

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