I would use a handheld shortwave receiver (Grundig E5 or equivalent)
and take a walk around the house and neighborhood when the
interference is occurring with some regularity. The receiver would be
tuned to the frequency at which the signal is strongest until I got
close then I would either tune off the strongest frequency slightly
and look further for an increase in signal strength or tune to a
harmonic multiple of the strongest frequency to see if the strength is
lower.
The receiver should have some sort of signal strength indicator and an
attenuator. The high end alternative would be something like the ICOM
R-3 with a step attenuator attached via a barrel male BNC adapter and
a small loop antenna to find nulls.
I have tracked down HF interference sources using a small loop antenna
I bought from Antennas & More (If I recall correctly) and an R3. By
walking or driving in a circle (more or less) around the perimeter of
the interference, I was able to find nulls and draw lines on a map.
Where the lines crossed I went in close and found the source.
Sometimes, if you are lucky, pulsing sources will be rich in harmonics
so that when you get in close you can hear them at successively higher
frequencies into the VHF spectrum. If I can hear the source in the VHF
spectrum I can usually DF it with a smallish Yagi and a receiver with
an attenuator.
Good luck!
73,
Frank N. Haas KB4T
-----Original Message-----
Message: 1
Date: Sat, 11 Jul 2009 02:44:11 -0500 (CDT)
From: "Christopher E. Brown" <cbrown@woods.net>
Subject: [RFI] Looking for ideas about yet another noise source
Attempting to track down a bothersome very intermittant noise and
looking for some ideas. Don't have a decent way to record it, but may
need to set something up if I cannot make headway.
Noise is pulse, appears on at least 80-20, strength higher around 20.
On the lower freqs, it is more of a static rush but time compressed,
it is also seemingly random, twice in 5 seconds, nothing for 40 sec,
once, and so on. Seems to be there almost any time of the day or
night.
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