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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