[RFI] Introduction - power line noise
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
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
More information about the RFI