Topband: [RFI] Powerline noise question

[Don Kirk]

Rick,

When I mentioned using an AM radio with a 3 or 4 element yagi when within
0.25 miles of the source I should have said that’s up on VHF (like 136 or
146 MHz, etc.) if it’s really power line noise (arcing hardware).

Don wd8dsb

On Thu, Dec 29, 2022 at 11:27 PM Don Kirk <wd8dsb at gmail.com> wrote:

> Hi Frank,
>
> Thanks for mentioning my portable flag, and that's the way to go to get
> close to the area of the suspect pole but I didn't want to toot my own
> horn.  It really is an easy antenna to build and its build is very
> forgiving, and glad to hear it exceeded your expectations.
>
> I do recommend using my portable flag out in the clear in order to avoid a
> distorted pattern such as developing a minor lobe off the backside if
> standing too close to an existing object like a tall metal light pole or a
> house, etc.  When in doubt I use the peak of my portable flag as it's much
> more robust (less prone to getting altered by nearby objects).  The
> unidirectional properties of the portable flag is priceless as well as its
> broadband response.  I use a 680 ohm termination resistor but a 820 ohm
> termination resistor works well too.
>
> 73,
> Don (wd8dsb)
>
> On Thu, Dec 29, 2022 at 10:54 PM Frank W3LPL <donovanf at starpower.net>
> wrote:
>
> > Hi Rick,
> >
> > I recently built a WB8DSB man portable flag antenna (March 2021 QST)
> > for RFI geolocation, its performance far exceeds my expectations.
> > Its narrow deep null quickly, easily and definitively located the
> > source of very troublesome 160 meter RFI to a single power pole
> > more than three miles from my QTH.  Prior to constructing the
> > flag antenna I could locate the RFI to only within a few hundred
> > yards of the RFI source.
> >
> > I built my flag antenna entirely out of materials I had on hand
> > from previous projects including 3/8 inch diameter fiberglass rods,
> > a pair of Advanced Receiver Research P1-30/20VD 20 dB HF preamps,
> > a case of eight AA batteries to provide power to the preamps,
> > a switchable attenuator and a Tecsun PL330 portable HF receiver.
> >
> > I highly recommend this easily constructed RFI geolocation antenna
> > for the toolkit of any serious HF operator.
> >
> > 73
> > Frank
> > W3LPL
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "Richard" <richard at karlquist.com>
> > To: "rfi" <rfi at contesting.com>
> > Sent: Friday, December 30, 2022 3:15:32 AM
> > Subject: [RFI] Powerline noise question
> >
> > I have a powerline noise coming from about 2 miles away, which is
> > nevertheless quite strong at my QTH.
> >
> > Here are the symptoms:
> >
> > 1.  A 120 Hz noise burst at regular intervals, about 0.9 seconds apart.
> >
> > 2.  The noise goes away after a rain; then comes back after things dry
> > out.
> >
> > 3.  Can be heard from 500 kHz up to a few MHz.
> >
> > 4.  The noise is very strong along a road for a few miles.  There is a
> >
> > power line that follows the road.  I haven't been able to localize it
> > better than
> >
> > that so far.  From my QTH, though, it is definitely coming in at a
> > specific azimuth
> >
> > which is consistent with the noisy road a few miles away.  (Using a loop
> > antenna
> >
> > for DF'ing).
> >
> > Any help appreciated.
> >
> > --
> > Rick Karlquist
> > N6RK
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