Kelly,
This is not a direct answer to your question but may lead you down a path to
the source.
My first guess at the source of this problem would be an electric fence,
which would be an impulse (broadband) source. Day-to-day variations in
amplitude are also consistent with an electric fence, the variations being
caused by weather (moisture), vegetation, and other physical changes in the
fence circuit. You may only be hearing it over a limited frequency range
because the antenna (the fence) might be a more efficient radiator in your
direction at some frequencies than at others. That effect could also combine
with differences in your system (receiver plus antenna) sensitivity at
various frequencies.
A drive around your area while listening on the AM broadcast band may locate
a candidate source. You could then backtrack from there to confirm that as
the problem emitter. This is a slightly backward approach, but electric
fences are usually easy to find.
Regards,
Stu Benner
www.emcwizard.com
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Kelly Johnson
Sent: Monday, October 02, 2006 7:57 PM
To: rfi@contesting.com
Subject: [RFI] DFing an HF RFI source
I have an RFI source in my neighborhood that I'd like to track down, but
could use some advice.
The noise source sounds like a "click" or small burst of energy at
approximately 1Hz. In other words, I hear a burst of RFI a little faster
than once per second. It seems to be relatively narrow band. I don't hear
it below 17 meters. It is strongest on 17 meters, but I can sometimes hear
it on 15 meters and maybe even 10. I've never heard it above that. I have
DF'd the general direction using my tower mounted HF yagi and the RFI peaks
at about S7 or S8 on 17 meters which is fairly strong, however I can't hear
it when I walk the neighborhood in that direction with my FT-817 and a whip.
I obviously can't carry a 17 meter yagi around the neighborhood. What other
decent antenna can I use to DF something doesn't appear to be broadband
enough reach into the VHF region?
FYI - The strength of this noise source varies from day-to-day and some days
I don't hear it at all, but it's there most of the time.
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