Charles, dfing your noise source at 440 MHz should be an easy one. The
obstacles you have as you know are the wires above you radiating the noise
and affecting the directional ability of your yagi.
If I were you I would opt for walking around all three or four poles. If
you're doing that with an antenna people will be inquisitive but it's rare
that they would tell you your trespassing. Explain to them that you're
looking for something arcing on the pole that could create a fire and power
outages. That's not necessarily the case but it certainly is a possibility.
I would be very surprised to find your problem slack insulators because of
the strength of the noise. Using attenuation at 440 should be extremely
effective. Remember when using ultrasound direct line of sight to the
sources important and the height of the pole could mean attenuation for
you. The Homebrew ultrasound devices don't have an overwhelmingly level of
gain so it's important to get around the pole and as close as possible and
then work your way out. During the triangulation process it's very
important to be away from the pole and A good rule of thumb is about half
the distance between the poles as a distance that you maintain from the
pole One Direction finding. Another thing you'll want to do is point your
440 yagi at the top of a pole that's reading the noise and find the
frequency that gives you the most gain. You may be amazed at how much more
gain you get out of that antenna when you find the exact frequency that
that antenna works best. rotate your antenna from horizontal to diagonal in
your signal level should be strongest when you're antenna is in the
diagonal position. If it is not you are not at the right pole.
Today is my family Christmas get together so I got to run. Best wishes to
you.
Michael Martin
RFI Services
51 W Bay Front Rd
Lothian, MD 20711
240-508-3760
mike@rfiservices.com
www.rfiservices.com
On Sat, Dec 31, 2022, 8:33 AM 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)
>
>
>
>
>
>
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|