Even without a spectrum display, just tuning across the band may tell you
whether it's likely to be power line or electronics. Line noise will be nearly
constant over hundreds of kHz, while that from electronics will show broad
peaks every 10-200 kHz, and will probably drift around. If an electronic source
is fairly stable, you may be able to identify it when tracking just by the
frequency.
73,
Scott K9MA
----------
Scott Ellington
--- via iPad
> On Mar 21, 2021, at 5:14 PM, Gary <gary_mayfield@hotmail.com> wrote:
>
> Jim,
>
> Thanks for the info and links. They were very interesting. It looks like I
> need to invest in an SDR of some kind, as I have no way to produce a
> waterfall wider than a couple KHz right now. I've had such good luck with
> simple direction finding in the past.
>
> Do you think the SDRplay RSP1A is a good option? Have you come across a
> better more portable option?
>
> Thanks for the help and Suggestions! (keep them coming!)
> 73,
> Gary "Joe" kk0sd
>
> -----Original Message-----
> From: RFI <rfi-bounces+gary_mayfield=hotmail.com@contesting.com> On Behalf Of
> Jim Brown
> Sent: Sunday, March 21, 2021 6:29 PM
> To: rfi@contesting.com
> Subject: Re: [RFI] New Interference at kk0sd
>
>> On 3/21/2021 1:28 PM, Charles Plunk wrote:
>> Its sounds like 120hz to me (power lines ). I recorded a segment and
>> run it through Audacity, expanded it out, and can see the spikes at
>> about that rate.
>
> Sound of the noise in an RX can be deceptive. Some electronic noise sources
> SOUND like impulse noise but they are not. The excellent DF advice from
> several very smart guys is exactly right IF it is impulse noise, but because
> most electronically generated noise comes from power handling or control
> equipment (switch mode power supplies in equipment and battery chargers,
> variable speed motor controllers), it will also have very strong components
> at power frequencies. And all power control noise will show the same 60, 120,
> and their harmonics, just like impulse noise.
>
> These power control devices use square and rectangular waves in the range of
> 10-20 kHz to do their thing, and they produce strong harmonics all the way up
> to 10M and beyond. Unlike impulse noise sources, they don't usually get up to
> 2M or 440 MHz where we can chase them with our directional antennas tuned to
> those frequencies -- instead, we must chase them where we can hear them. In
> addition, most of us have MANY noise sources, so it's easy to get on a wild
> goose chase if you don't know which kind of noise you're chasing.
>
> THAT'S why I keep urging folks to study the waterfall FIRST.
>
> 73, Jim K9YC
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