[RFI] Impact of bandwidth when trying to analyze broadband RFI (like power line noise) using the AM audio spectrum

[Michael Martin]

If the noise pattern shown is an active power line noise, I would bet that it is an arcing lightning arrester (LA). A typical sparking source would occur much faster during the positive and/or negative half of the cycle. The spacing between the spikes on each half of the cycle have an increased amount of time between the discharges. I spent years studying lightning arresters trying to figure out why this happens. This is an example I present during my RFI Workshops.
I literally have thousands of these examples and have analyzed the sources and it was an easy figuring out why lightning arresters create this issue/pattern.
Check out RFIservices.com workshops.

That's a very good example.
Thank you very much,
Mike Martin
RFI Services
240-508-3760
51 W Bay Front Rd
Lothian, MD 20711
rfiservices.com
________________________________
From: RFI <rfi-bounces+mike=rfiservices.com at contesting.com> on behalf of Don Kirk <wd8dsb at gmail.com>
Sent: Wednesday, November 26, 2025 3:41:14 PM
To: RFI <rfi at contesting.com>
Subject: [RFI] Impact of bandwidth when trying to analyze broadband RFI (like power line noise) using the AM audio spectrum

As I mentioned in a recent post I have had much better success observing
the AM audio spectrum for power line RFI and other broadband noise when
using a bandwidth much wider than conventional receivers typically
provide.  I now use at least a bandwidth of 25 KHz, and prefer a bandwidth
of 100 KHz whenever possible.  I just created a simple website to show the
impact of a 5, 10, 15, 20, 25, 50, and 100 KHz bandwidth for those
interested, and here is a link to the website:
https://sites.google.com/view/bwforpowerlinerfi/home

Just FYI, and 73.
Don (wd8dsb)
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