nice info Jim. This list benefits by work done by you and others.
Kudos to you and all that contribute.
73
Dave wo2x
Sent from my waxed string and tin cans.
> On Nov 23, 2025, at 6:01 PM, Jim Brown <jim@audiosystemsgroup.com> wrote:
>
> The RFI signatures that are most useful in providing clues about the nature
> of the source are wide waterfalls of the IF or RF. NOT audio -- almost all
> noise sources are somehow related to mains power.
>
> Noise that show up as vertical humps of noise spaced from each other in the
> range of 30 - 60 kHz, and that may drift around a bit are some sort of
> power-handling electronics, like SMPS (wall warts, line lumps, chargers, even
> built into products like TVs, stereo gear) and controllers for variable-speed
> drive motors.
>
> Narrow straight vertical lines are from devices like microprocessors.
>
> Horizontal lines are impulse noise, generated by lightning and arcing at
> various forms of hardware on power lines.
>
> About ten years ago, I published an on-line tutorial showing typical
> waterfalls, and NK7Z responded with a lot of excellent work using an
> inexpensive SDR receiver. The first link is to a piece that ran in NCJ, the
> second to slides for a talk I did at Pacificon and Visalia, and to several
> clubs. The talk was later, so includes more graphics.
>
> http://k9yc.com/KillingReceiveNoise.pdf
> http://k9yc.com/KillingRXNoiseVisalia.pdf
>
> 73, Jim K9YC
>
>> I am working on a RFI case that we believe is coming from a nearby home.
>> The owner is a little cooperative, but is not interested in doing a ckt
>> breaker test. The noise exhibits some interesting characteristics that may
>> help us in suggesting he unplug a device. Perhaps someone has seen this
>> before.
>
>
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