Hi Gary,
Not sure if I can do attachments on this reflector, but attached is a
screen shot showing the quick audio analysis I did on your recording that I
previously mentioned. The red cursor lines are spaced so they indicate a
frequency of approximately 60 Hz.
Just FYI,
Don (wd8db)
On Sun, Mar 21, 2021 at 4:21 PM Don Kirk <wd8dsb@gmail.com> wrote:
> 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> 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
>>
>>
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>>
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|