Frank,
Great comment about the electric fence, and I previously dealt with an
electric fence case at W9RE and it indeed had a rate of approximately 1
second. It was a very brief discharge every second and if I were to
describe it, it sounded like tick, tick, tick with each tick being spaced a
second apart (the ticks were very brief). We were able to hear it at great
distances just using my old car AM radio that has no noise blanker
technology whereas it could not be heard on a modem cars radio that Mike
W9RE had. I believe most modern car radios have noise blanker technology
that makes them less useful for RFI detection.
Don wd8dsb
On Thu, Dec 29, 2022 at 11:23 PM Frank W3LPL <donovanf@starpower.net> wrote:
> Richard,
>
> I forgot to mention that electric fence RFI typically has
> a definitive repetition cycle similar to what you described
> and often goes away during rain.
>
> 73
> Frank
> W3LPL
>
> ----- Original Message -----
> From: "Don Kirk" <wd8dsb@gmail.com>
> To: "Richard" <richard@karlquist.com>
> Cc: "rfi" <rfi@contesting.com>
> Sent: Friday, December 30, 2022 4:07:12 AM
> Subject: Re: [RFI] Powerline noise question
>
> Hi Rick,
>
> Sorry that my last message was blank as I typed it on my cell phone and
> then accidentally deleted the text prior to hitting the send key.
>
> You can use your MF/HF loop to do some triangulation on the source but you
> often need to get far away from existing power lines to avoid receiving
> conducted signals along the lines versus the signal direct from the
> source. As an example when out in the country I will often walk out into
> the middle of farm fields to get away from overhead power lines when
> obtaining bearings. As you get closer to the source you can go higher in
> frequency if it really is power line noise (arcing hardware). As an
> example you can go to 40 meters then 20 meters and then 10 meters as you
> get closer to the source as a form of attenuation and to also help you get
> multiple wavelengths away from objects that might otherwise skew your
> readings. Adjustable RF gain and/or attenuators are also very helpful.
>
> If it really is power line noise (arcing hardware) you should be able to
> hear the source using an AM receiver with a 3 or 4 element yagi when you
> are within approximately 0.25 miles of the source (and sometimes upto 0.5
> or more miles away). Make sure the yagi is tuned for the frequency you are
> using in order to assure the correct antenna pattern. When you get very
> close to the suspect pole you will typically need to throw in 20 to 30 dB
> of attenuation in order to determine the exact pole (in rare cases you
> might even need 40 dB of attenuation).
>
> One thing that is great is that it sounds like your source has a specific
> pattern that will help you differentiate it from other sources but if the
> pattern is always a very specific 0.9 second pattern that never changes
> regardless of what day you listen, etc. that makes you wonder if something
> else is going on, but the fact that it goes away when it rains is typically
> a good indicator that it's indeed power line noise (arcing hardware).
>
> Don (wd8dsb)
>
> On Thu, Dec 29, 2022 at 10:46 PM Don Kirk <wd8dsb@gmail.com> wrote:
>
> >
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