Thanks Jim, that is very helpful. I've tracked down a few arcing poles in the
past and because this one is extremely broadband (no humps or areas of
intensity) and sounds like power line noise (loud buzzing, however it is
extremely constant) I was guessing that it was power line noise.
Others and, some off,list have pointed out that it could be something
electronic or a grow light that is lighting up the whole line.
I'll post back once I can get closer to the utility drop that I located with
the loop antenna!
I really appreciate your input!
David
NY6W
> On Feb 21, 2016, at 5:17 PM, Jim Brown <jim@audiosystemsgroup.com> wrote:
>
>> On Sun,2/21/2016 4:27 PM, David Winarsky wrote:
>> Thanks, what has me puzzled is I have S7 noise on 10 meters and with the
>> loop antenna, I believe I have it tracked to a utility drop for a house 2
>> doors down; however I don't pick anything up on 2 meters or 440.
>
> There's another fundamental principle here that some are overlooking. The
> noise PRODUCED by power systems is nearly always the result of ARCING, so it
> is IMPULSE NOISE. This noise is, by its nature, quite broadband, although its
> spectrum is often shaped by the transmission medium. Impulse noise often
> extends from power frequencies to UHF, but the parts of the antennas that
> radiate it are generally most effective very close to the source. The lower
> frequency components are radiated by much longer wires, and are sometimes
> conducted along those wires as a transmission line, to lower frequencies are
> not nearly as effective for locating the source. When we use an AM RX at VHF
> and UHF, we are using that principle -- when the signal is strong at UHF,
> we're zeroing in on the source.
>
> The above principle does NOT apply to most ELECTRONICALLY GENERATED NOISE,
> simply because it's NOT an impulse. Rather, it's a square wave, usually in
> the high audio spectrum, with a TON of harmonics produced by the rise time of
> the square wave. These sources are FAR less broadband -- they are typically
> harmonics of the square wave intentionally freuency-modulated by random
> noise to get around FCC regulations about power in a single frequency (in the
> digital world, we might describe that modulation as dither). If the noise
> source is a free-running oscillator or clock, it will usually drift (a lot)
> as it warms up, so we hear these noise sources as humps of noise as sidebands
> of a carrier that drift up or down the band. These drifting humps of noise
> are the signature of a SWITCH MODE POWER SUPPLY.
>
> If the noise does NOT drift, they're likely a clock for a microprocessor.
>
> We CANNOT chase ELECTRONIC SOURCES with a VHF or UHF FM receiver, because
> they are NOT impulses, and because they rarely have much spectra up there.
> Rather, we much chase them with an MF or HF RX that can tune to the part of
> the spectra where they are strong, ideally where they are bothering us.
>
> CAPS added for emphasis and clarity. :)
>
> There are experts lurking here who are professional noise chasers and far
> more experienced than I, so I'll defer to them on their methods. I'm simply
> trying to improve understanding.
>
> 73, Jim K9YC
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