Hi Pete,
The primary rule when tracking down any RFI or intermod source is
to turn off all power in your home and all UPSs. This includes UPSs
that are easily forgotten such those integrated into tele phone,
laptop computers and network equipment. Its also wise to disconnect
all antennas and control lines to your station.
Only after you've completed that basic first step does it make sense
to start looking outside your home. The same applies to intermod
from external emitters and buzzing harmonics of your own transmitted
signal, all of which can be caused by devices in your own home.
73
Frank
W3LPL
----- Original Message -----
From: "N4ZR" <n4zr@comcast.net>
To: "RFI List" <rfi@contesting.com>
Sent: Tuesday, January 28, 2020 5:05:53 PM
Subject: [RFI] AM Broadcast Intermod?
I'm embarrassed to admit that I had overlooked a noise-maker in my
shack, my 1 TB USB disk drive. I cleaned that up with a few turns of
the DC power cable around a type 31 toroid, and now I've uncovered
something under it. It's a wideband signal (tuning makes no
difference), but sounds very much like a badly distorted broadcast station.
Just on a hunch, I tried tuning across the AM broadcast band, and found
a loud AM sports radio station on 1570 KHz that appears to be
broadcasting the same content - pauses, pitch of voices, etc. all seem
to match.. Unfortunately, just before I could get set up to record, the
voices on 160 suddenly went away. I'm assuming they'll be back, and
while I wait to get a recording I'm wondering:
* Does this sound like intermod, or some other phenomenon?
* Is it the result of something wrong at the station?
* If so, how best to approach them about it?
--
73, Pete N4ZR
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at <http://reversebeacon.net>, now
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