Hi Jeff,
My consistent practice is to identify the highest frequency where
I can hear the RFI in my shack. I then use my directive antennas
to determine the bearing on which I should search. I can
consistently determine azimuth within better than ten degree
accuracy on any band. I begin my search on that frequency
with the PL-660 in wide band AM mode, walking or driving
along the line of bearing.
The PL-660 has a built in loopstick antenna very useful for
direction finding but active only in the AM broadcast band
(540-1700 kHz). Above 1700 kHz it uses a short retractable
whip antenna (slightly useful for direction finding) or an
external antenna.
Usually (but definitely not always) the RFI can be heard on higher
frequencies as you get closer to the source, in many cases up the
the aircraft band or all the way up to 450 MHz (on a different
receiver). So far my most distant RFI was AC power line RFI
very strong at my QTH that originates four miles away, It was
a serious visible arc on a 34 kV subtransmission line (not a local
13 kV distribution line). The power company was very
motivated to repair it quickly.
This recent RFI was very different than anything I've ever
experienced, I could hear the RFI only on the 160 meter band
(about 1500- 2000 kHz) It sounded like white noise with no
audible 60 Hz (or 60 Hz harmonic) component, The only
way I could locate it was by using the PL-660 S-meter with
the PL-660 in wideband AM mode. It turned out to be a
malfunctioning Travellers' Information Station transmitter
at 1700 kHz. Local hams have an excellent relationship with
the county Office of Emergency Management that operates the
transmitter and they turned it off within hours of being notified
of the problem.
This is only the second RFI that I've experienced that affects
only 160 meters. The first one was very intense RFI that
sounded exactly like classic AC power line RFI but strangely
it affected only 160 meters and the AM broadcast band.
It turned out to be a malfunctioning electric fence charger
one mile away that was stuck continuously on, not pulsing.
Unfortunately the landowner (an electrician!) was very
belligerent about refusing to replace his fence charger, but
some aggressive "social engineering" motivated him to
change his behavior.
73
Frank
W3LPL
----- Original Message -----
From: K1ZM@aol.com
To: donovanf@starpower.net
Sent: Tuesday, February 16, 2016 10:08:22 AM
Subject: Tecsun 660
Hi Frank
I read your emails on your RFI search.
Youmay have mentioned it, but what FREQ BAND did you use on the TECSUN in
your search for the source?
Was it the AIRCRAFT BAND on FM?
The reason I ask is that I have a similar radio - that is very similar to
the radio you used - just made by SONY.
I wonder if I could use it like you did? I am 99% sure it has the aricraft
FM band in it.
Pls let me know when you can.
Tks
73 JEFF</HTML>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|