I just sent this to the fellow in Waco. I'd recommend getting the PC ap
called Zelscope which is a software based scope. It was ten bucks a few year
ago. (there are also several free iphone aps which do this too - audio spectrum
analyzers) Hook receiver to sound Card and you can see the waveform, determine
base frequency. You can then snapshot the screen and show the waveform which
will have certain group of peaks. Arrl would characterize as "3 peak, 4 peak,
5 peak" but you would also see if there are multiple sources of the noise or a
single one.
If this is a single source a MFJ1025 nuller will work nicely to eliminate it
with the proper sense antenna and some twidling of the controls to null out the
crud.
After years of working with ARRL and the power co here we identified 4 sources
of gap noise and they they fixed all but one (because an idiot neighbor blocked
access to the right of way and they haven't got around to dealing with them
yet since the problem isn't affecting safety or other power transmission
issues.).
But now with the sole source of crud I can null it out all the time on most
bands including 160 but as you tune across the band you have to re null since
the line changes the crud noise phase along its length. There are some
frequencies where nulling can't be had (altho by reorienting the sense Antenna
or setting up a second one it can. I have three sense antennas out there for
this purpose.
Sent from my iPad
On Feb 11, 2014, at 15:58, "Bruce" <k1fz@myfairpoint.net> wrote:
> Getting noise from my NW direction. Does not seem to be local. Started
> wondering what, at distance, could be causing it. At times it seems to have
> a rhythm like a motor.
>
> There are a lot of power generating wind mills showing up. Checking through
> Google, they generate DC and convert to 3 phase AC it with an inverter. The
> frequency and phase of the inverter is controlled with a sample from the
> power grid.
>
> Could their inverters have enough sine wave distortion to have harmonic
> energy?
>
> So my question is: Does anyone have first hand knowledge of interference on
> the low bands from power generator wind mills?
>
> Bruce-K1FZ
> www.qsl.net/k1fz/beveragenotes.html
> www.qsl.net/k1fz/pennantnotes.html
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