Ed will remember the AT&T modems on 80 meters.
I had good luck tracking them down in Petaluma and locating each one to
specific rooms in a development of single-story duplexes.
It was Super Bowl Sunday and when people sharing cable co. services saw
someone with antennas on his car and a "sniffer" (AOR 8000 with an
untuned loop) they were running behind their houses to remove the
illegal taps.
A 3-6 inch loop of rigid or even fairly stiff coax can be directive
enough to find these harmonics and then at lower frequencies march right
up to the source. H-field coupling drops off VERY fast away from a
radiating conductor.
Cortland
KA5S
On 10/28/18 3:54 PM, Hare, Ed W1RFI wrote:
"What is it?" is the wrong question. If someone said that it is a model Z-123 Netstuff
modem, that really wouldn't help much. The real question is: "Where is it?" Finding the
house or location where the noise is originating is what you will get to eventually, so start with
that question.
Many noisy devices can sound similar, so if someone tells you that it is a
Z-123, and it is really a lighting ballast instead, you will be on a wild-goose
chase.
Ed, W1RFI
________________________________________
From: RFI [rfi-bounces@contesting.com] on behalf of donovanf@starpower.net
[donovanf@starpower.net]
Sent: Sunday, October 28, 2018 3:04 PM
To: rfi@contesting.com
Subject: Re: [RFI] Signals on 160
Hi Gary,
Of course, the first thing you should do is turn off all of the AC
power -- including UPSs -- in your own home to determine if any
of the RFI disappears.
I don't think anyone will be doing you a favor by helping you guess
what these signals might be. By far the best way to determine what
they are is to build -- or if necessary buy -- a simple small loop antenna.
A loop antenna has a deep, narrow azimuth null off of each side of
the antenna that allows to quickly identify the RFI source.
Good luck!
73
Frank
W3LPL
----- Original Message -----
From: "Gary Smith" <Gary@ka1j.com>
To: rfi@contesting.com
Sent: Sunday, October 28, 2018 5:31:51 PM
Subject: [RFI] Signals on 160
I've been encountering some strong signals
on 160 recently. I made some approximate
guesses at the frequency using the P3
markers to measure them. Here's the
signals at 1:20PM local time with a center
frequency of 1.848.67
The main signals are about 42 KHz apart.
The lesser spikes in-between appear at
somewhat regular intervals.
http://doctorgary.net/spikes-on-p3.jpg
Here's the measured values of the main
signals
http://doctorgary.net/frequencies.jpg
Any idea what might be the source of
signals spaced like this?
73,
Gary
KA1J
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