Hi Don,
Very nice job, I've used similar methods to accurately track down power line
noise at W3LPL. My power company is very responsive when I give them reliable
RFI location information.
I use a Yaesu FT-847 in my vehicle with a short vertical whip antenna to track
power line noise on the HF bands. You don't need a large vertical antenna on
your vehicle because you're usually looking for strong signals. The FT-847 is
particularly effective because it covers all ham bands from 1.8 to 450 MHz, and
it has an excellent S-meter and AM detector. I've tried using my Elecraft K-3
but its S-meter and rather poor AM detector are serious impediments to success.
For locating individual poles I use a handheld Yaesu FT-817 and a six element
handheld 440 MHz Yagi.
73
Frank
W3LPL
---- Original message ----
>Date: Fri, 4 Jan 2013 08:08:11 -0500
>From: Don Kirk <wd8dsb@gmail.com>
>Subject: Topband: Power Line Noise Direction Finding
>To: topband@contesting.com
>
>Hello Topbanders,
>
>For the past few months I have been plagued by what I suspected was power
>line noise on 160 meters, and finally was able to track it down to a power
>line pole 0.66 miles from my house and learned a bunch during the process.
>While this topic has been covered in the past, I thought some info from my
>recent exercise might be useful to others (and a good reminder of what
>techniques work). Here is a link to a simple website I created that
>contains pictures, oscilloscope screen shots of receiver audio, and links
>to video recordings that I made.
>
>http://sites.google.com/site/powerlinenoise/
>
>The factors which really helped locate the noise source were as follows :
>1) My 160 meter pennant RX antennas indicated the noise was originating NE
>from my house.
>2) Ability to hear the noise on 1710 khz on my car radio while driving
>around which helped me zero in on a section of power lines (but it was
>impossible to zero in on a particular pole).
>3) Observing (using oscilloscope screen shot of audio on 160 meters using
>radio in AM mode) that noise frequency was 120 hertz which is typical of
>power line equipment arcing (arcing each half of the sine wave).
>4) Direction finding using VHF AM radio (portable scanner with AM aircraft
>band capabilities listening on 136 MHZ) using a portable 4 element
>horizontal beam and 20 dB attenuator that I was able to switch in as I got
>close to the source.
>
>Notes :
>1) I tried using a portable 160 meter AM radio with portable shielded DF
>loop, but I was unable to zero in on the suspect pole (with 100 percent
>certainty) using this equipment, and it was not until I used the VHF AM
>radio with lots of attenuation that I was able to identify the suspect pole.
>2) VHF direction finding beam worked much better when mounted horizontally
>(peak and null data made much more sense).
>3) I used EZNEC demo to confirm the amount that I need to lengthen the
>elements on my two meter beam in order to maintain the proper beam pattern
>when used on 136 MHZ. I used alligator clips to lengthen the elements and
>this worked out just great (nothing fancy).
>
>73's
>Don (wd8dsb)
>_______________________________________________
>Stew Perry Topband Distance Challenge coming on December 29th.
_______________________________________________
Stew Perry Topband Distance Challenge coming on December 29th.
|