[RFI] Topband: Powerline noise question

[Don Kirk]

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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