Good work and thinking, Don. Sometimes noise is tough to locate.
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/
Listening though narrow filters tends to make all noises look increasingly
the same, eventually with enough selectivity they all become sinewaves. This
is why waveforms on receiver audio outputs, especially with narrow filters,
has limited value. Using your logical deduction, a 120 Hz audio output is
typical of a single phase arc.
120Hz audio tone noise can also be a full wave line rectified, poorly
filtered switching supply. But in that case the noise is frequency periodic
as the dial is turned.
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.
That is pretty much how it always works. Low frequencies get it to the
general line, and increasing frequencies get it narrowed to an area.
I use this unit, although a wide selectivity AM portable all band receiver
would do almost as well:
http://www.w8ji.com/power_line_noise.htm
Locating noise is an application where more bandwidth is usually much
better.
73 Tom
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Stew Perry Topband Distance Challenge coming on December 29th.
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