I addressed a similar problem two summers ago. I used a home brew
0.5-meter shielded loop with its extremely sharp nulls to isolate which
pole of five was the culprit. I coupled the small loop through a BB
transformer to a hand-held scanner using AM demodulation tuned to a
broadcast-free frequency to serve as a receiver. The setup worked quite
well.
Dave - WØLEV
On Sat, Dec 31, 2022 at 1:33 PM Charles Plunk <af4o@twc.com> wrote:
> Being as we are on the subject :-) You guys have skillfully helped me in
> the past locate some awful nearby 120hz sources and I appreciate it.
>
> I have been casually tracking a 120hz source since the summer. Casually
> because it is distant (other side of the neighborhood ~ 1800' away) and
> I can mitigate it with noise blankers etc ~90% of the time. I located it
> to within 3 power poles. All 3 have bell end insulators and a couple of
> the spans are slack. Its likely old hardware probably 60's (I have good
> reason to believe this). Single phase 7.2kv (only other on the poles is
> cable/phone). Houses all around.
>
> I did match the pattern by re-transmitting the station audio. But cannot
> determine, with HT/Yagi's, which pole for sure its coming from as its
> well conducted throughout all 3. And it maybe more than 1 of them. Up
> close I can hear it on 440mhz on all 3 poles. Not enough real estate
> without trespassing to back far enough off to get out from under the
> lines to triangulate which pole better (if it is a single pole or not 2
> or 3).
>
> I did request they replace the insulators on all 3 poles (and tighten
> the spans) as they are about the only hardware on all 3 poles on the
> 7.2kv. That was back in the summer. Have not heard back from them (and
> they have not done last time I was by there) and I have not pressed it
> admittedly.
>
> Should I press them to do all 3 or try to isolate to a single pole or 2?
> Even using attenuator's I doubt I will be able to determine with
> certainty which pole as all 3 had a close signal strength. I have not
> tried the flag antenna. I could try that and attenuators to isolate
> before I contact them again. Or setup something higher in frequency.
> Unfortunately could not hear anything with ultrasonic. Any other
> suggestions?
>
> Thanks
>
> Chuck
> W4NBO
>
> FT60 on AM mode
>
> FT817
>
> 2 meter handheld yagi
>
> 440 handheld yagi
>
> QST homebrew ultrasonic dish (has worked well on other sources)
>
>
>
>
>
>
>
> _______________________________________________
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> http://lists.contesting.com/mailman/listinfo/rfi
>
--
*Dave - WØLEV*
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