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Re: [RFI] 80M mystery noise

To: "'Pete Smith'" <n4zr@contesting.com>, <rfi@contesting.com>
Subject: Re: [RFI] 80M mystery noise
From: "Tim Duffy K3LR" <k3lr@k3lr.com>
Reply-to: k3lr@k3lr.com
Date: Tue, 13 Nov 2007 15:50:39 -0600
List-post: <mailto:rfi@contesting.com>
Hi Pete!

I had a very similar warbler that we used to hear on 160 and 80 meters at
K3LR. Every 4 KHz. Using my Icom R1 handheld CW receiver, a step attenuator
and mobile whips I DFed the culprit. It was my neighbors security system. It
did not matter if it was "armed" or not. A W3NQN AC line filter on the
security system fixed the problem. I believe the switching power supply in
the security system was using the AC line as an antenna.

Tim K3LR

DX Cluster Telnet dx.k3lr.com

-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Pete Smith
Sent: Tuesday, November 13, 2007 3:40 PM
To: rfi@contesting.com
Subject: [RFI] 80M mystery noise

This thing (or rather, thingS) has appeared in the last few months.  It 
occurs at intervals across the CW band, at widely different signal 
strengths, regardless of time of day (high noon, for example), so it must 
be near field or groundwave.  The intervals appear to be roughly every 1.8 
KHz, but the signal strengths vary so much that I'm tempted to speculate 
that it may be a number of identical devices at different distances from 
me, and with slightly different frequency-determining components.  Or, 
conceivably, they are all harmonics of a 1.8 KHz source.  I can't DF it at 
all precisely, due to a lack of sufficiently directive RX antennas (a K9AY 
loop just doesn't cut it hi), but most of them appear to be north of me.

The enclosed recording was done in CW position, on my Mark 5 with 2.8 KHz 
filtering.  Looking at it on Spectran there are two distinct, fairly narrow 
alternating carriers, each of which shifts frequency slightly during its 
"on" period.  I caught one of them with the screen capture, but you can see 
from the waterfall that the other, which is slightly lower in frequency, is 
similar.  Nothing is audible in AM mode.

If you think you might be able to help ID this thing, please go to 
www.pvrc.org/n4zr/80m_mystery_noise.htm to listen to it and look at the 
Spectran signature.  Thanks!

73, Pete N4ZR
The World HF Contest Station Database
Full details on 3300 contest stations
Updated 5/5/07 http://www.pvrc.org/WCSD/WCSDsearch.htm

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