Several folks have pointed me at the Flag antenna article in the March 2021
QST. It looks like a winner. I will get going on that next weekend if needed.
Keep the ideas coming!
73,
Gary "Joe" kk0sd
-----Original Message-----
From: RFI <rfi-bounces+gary_mayfield=hotmail.com@contesting.com> On Behalf Of
Dave Cole
Sent: Sunday, March 21, 2021 10:00 PM
To: rfi@contesting.com
Subject: Re: [RFI] New Interference at kk0sd
There is a very nice article in this months QST on building a very good DFing
antenna with more gain than a loop... See the cover.
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 3/21/21 5:01 PM, Gary wrote:
> Don,
>
> Thanks for the suggestion. The 847 in the video does two
> meters in all modes. A swing of the 2 meter beam yields no noise. I can tune
> down to the airport VOR signal on 118 MHz and copy it clearly with no noise.
>
> I have a portable shortwave receiver and a loop
> antenna that served me well in tracking other issues, but I am not
> hearing the signal with my portable shortwave receiver and loop. I am
> not hearing it with the telescopic antenna either. I have a shortwave
> receiver in my pickup as well. I do not hear the noise when driving
> the neighborhood, so I figure it must be close…
>
> I have an MFJ-852 receiver it seems to go wild when
> broadside to either of my neighbor’s houses, but stays pretty quiet near my
> transformer box in the back yard.
>
> I will look into building a flag antenna for my portable
> shortwave receiver. I think it is a good next step.
>
> My utilities are underground so there aren’t really
> poles to check. I have tried the loop near all the boxes I can find
> with no results yet 😊
>
> 73, Thanks and Keep the suggestions coming!
> Gary “Joe” kk0sd
>
> From: Don Kirk <wd8dsb@gmail.com>
> Sent: Sunday, March 21, 2021 3:21 PM
> To: Gary <gary_mayfield@hotmail.com>
> Cc: rfi@contesting.com
> Subject: Re: [RFI] New Interference at kk0sd
>
> Hi Gary,
>
> I never like to guess what the source of the RFI might be, but here are some
> comments and suggestions.
>
> Do you have a 2 meter beam and a 2 meter radio with AM mode capability? If
> so you might be able to hear this noise from your house since it appears very
> strong on 20 and 15 meters.
>
> I did a quick analysis of the audio in your recording, and it's possibly
> arcing (or switching) which is typically happening at 120 Hz (one time each
> half of the sine wave) but sometimes only at 60 Hz, and every other half
> cycle looks similar to itself (like something is breaking down easier during
> one half of the sine wave versus the other half of the sine wave). The
> arcing is also intermittent (sometimes no arcing/switching during the time
> period of successive 60 Hz sine waves as an example).
>
> Just because you don’t hear it on the AM broadcast band or 160 meters from
> your location does not mean it’s not power line RFI. The more I track down
> power line noise the more I’m amazed how band specific it can be when not
> close to the faulty pole. If you have a cheap portable AM radio you probably
> will hear this junk when you get closer to the source. Using a cars AM radio
> can be hit or miss depending on the design of the radio, as it appears modern
> car AM radios have gotten much better in their noise blanker technology (I
> can hear arcing from a faulty power pole at great distances using the AM
> radio in my 25 year old Saturn, whereas I often can't hear any arcing when
> right next to a faulty pole in other vehicles that are more modern than
> mine). I suspect you will be able to hear this on 135 MHz AM when you get
> very close to the source if you have an HT that tunes down into the aviation
> band where the radio would switch to AM mode or if you have a cheap hand held
> police scanner capable of 135 MHz, etc.
>
> If you have a portable HF receiver I suggest you build a portable flag (see
> March issue of QST) and you will likely find the source of that noise (or
> narrow in on its location) very quickly since it appears to be very strong.
> It’s appears so strong on 20 and 15 meters in your video that you probably
> will not even need a preamp with the portable flag. You should be able to
> hear that noise from your yard and then walk right toward it using the
> portable flag. As you get close to the source you will likely need to reduce
> RF gain or insert attenuation. If it’s power line noise you might need to
> use 135 MHz AM with directional antenna when you get very close to the pole
> to isolate the pole from adjacent poles, and again would need attenuation
> (this assumes its a pole and not an in ground feeder, etc).
>
> Just some thoughts from my end.
>
> 73,
> Don (wd8dsb)
>
> On Sun, Mar 21, 2021 at 2:02 PM Gary
> <gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>> wrote:
> My last problem was tracked down to a neon sign in a neighbors garage. I had
> several months of blissful relatively low noise operation, but now have a new
> RFI issue.
>
> You can see a recording of it here:
> https://www.youtube.com/watch?v=GKf4P44FXMo
>
> I have turned all of the breakers in my home off and run the radio from a
> battery and the noise remains.
>
> My neighborhood utilities are all underground.
>
> There are no solar installations in my neighborhood, and the noise is there
> at night anyway...
>
> The noise is not detectable on the AM broadcast band, but starts around 2 MHz
> and runs to at least 6 meters.
>
> It is there 7 days a week 24 hours a day.
>
> It is not detectable from my pickup when I drive the streets of my
> neighborhood (checking both AM broadcast and Shortwave).
>
> If any one has heard something like this, I would love to hear what you found.
>
> Thank You for your input and help!
>
> 73,
> Gary "Joe", kk0sd
>
>
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