Hi Gary,
I never like to guess what the source of the RFI might be, but here are
some comments and suggestions.
Do you have a 2 meter beam and a 2 meter radio with AM mode capability? If
so you might be able to hear this noise from your house since it appears
very strong on 20 and 15 meters.
I did a quick analysis of the audio in your recording, and it's possibly
arcing (or switching) which is typically happening at 120 Hz (one time each
half of the sine wave) but sometimes only at 60 Hz, and every other half
cycle looks similar to itself (like something is breaking down easier
during one half of the sine wave versus the other half of the sine wave).
The arcing is also intermittent (sometimes no arcing/switching during the
time period of successive 60 Hz sine waves as an example).
Just because you don’t hear it on the AM broadcast band or 160 meters from
your location does not mean it’s not power line RFI. The more I track down
power line noise the more I’m amazed how band specific it can be when not
close to the faulty pole. If you have a cheap portable AM radio you
probably will hear this junk when you get closer to the source. Using a
cars AM radio can be hit or miss depending on the design of the radio, as
it appears modern car AM radios have gotten much better in their noise
blanker technology (I can hear arcing from a faulty power pole at great
distances using the AM radio in my 25 year old Saturn, whereas I often
can't hear any arcing when right next to a faulty pole in other vehicles
that are more modern than mine). I suspect you will be able to hear this
on 135 MHz AM when you get very close to the source if you have an HT that
tunes down into the aviation band where the radio would switch to AM mode
or if you have a cheap hand held police scanner capable of 135 MHz, etc.
If you have a portable HF receiver I suggest you build a portable flag (see
March issue of QST) and you will likely find the source of that noise (or
narrow in on its location) very quickly since it appears to be very
strong. It’s appears so strong on 20 and 15 meters in your video that you
probably will not even need a preamp with the portable flag. You should be
able to hear that noise from your yard and then walk right toward it using
the portable flag. As you get close to the source you will likely need to
reduce RF gain or insert attenuation. If it’s power line noise you might
need to use 135 MHz AM with directional antenna when you get very close to
the pole to isolate the pole from adjacent poles, and again would need
attenuation (this assumes its a pole and not an in ground feeder, etc).
Just some thoughts from my end.
73,
Don (wd8dsb)
On Sun, Mar 21, 2021 at 2:02 PM Gary <gary_mayfield@hotmail.com> wrote:
> My last problem was tracked down to a neon sign in a neighbors garage. I
> had several months of blissful relatively low noise operation, but now have
> a new RFI issue.
>
> You can see a recording of it here:
> https://www.youtube.com/watch?v=GKf4P44FXMo
>
> I have turned all of the breakers in my home off and run the radio from a
> battery and the noise remains.
>
> My neighborhood utilities are all underground.
>
> There are no solar installations in my neighborhood, and the noise is
> there at night anyway...
>
> The noise is not detectable on the AM broadcast band, but starts around 2
> MHz and runs to at least 6 meters.
>
> It is there 7 days a week 24 hours a day.
>
> It is not detectable from my pickup when I drive the streets of my
> neighborhood (checking both AM broadcast and Shortwave).
>
> If any one has heard something like this, I would love to hear what you
> found.
>
> Thank You for your input and help!
>
> 73,
> Gary "Joe", kk0sd
>
>
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>
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