[RFI] Power Line RFI

Doug Rehman doug at k4ac.com
Thu Dec 9 17:05:26 PST 2010


I've been working with my local power company to eliminate power line noise.
We had most of it eliminated until last week when a new noise source popped
up. This new noise source is horrendous (59+30dB on 80m and up to S8/9 on
10m). The power company's RFI guy came out a couple of days ago and tracked
it down to a specific pole.

The pole is about 1000' down the highway from me at a tee roadway
intersection.  Here's a poor attempt at a diagram:



                                                                  QTH
                                                      
------------------------------------------------------------------

------------------      -------------------------------------------
       X2      X1|      |Y1     Y2     Y3        Y4
                      |      |
                      |      |
                 X3|      |Y5
                      |      |


The RFI guy thinks that the noise is coming from X1 (X=other company's
lines; Y=RFI Guy's/My power company). There are no connections between the
two power companies' lines that is anywhere close to this area.

Listening on 2m SSB with the vertical on my truck, I get a very strong (S8)
noise from Y3-Y2-Y1-Y5. The noise drops off as you move from X1 to X2 and Y3
to Y4.  It also decreases as you move from X1/Y1 to X3/Y5.

If the problem pole is indeed X1 (belonging to the other company), would Y2
and Y3 be re-radiating the signal that strong at 144 MHz (remembering that
there is no connection to X1)?

Doug
K4AC



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