At 14:52 12/11/2005, WX5L wrote:
>For most of us we don't have sophisticated DF'ing equipment but a nifty
>device is the MFJ-852 Noise Locator. It receives in the AM aircraft band
>with attached dipoles but I went s step further. I installed a BNC female on
>the top then purchases a 4 element 2 meter beam installing a male bnc on the
>coax. It gives the 852 remarkable directivity. I have found though close in
>to a strong source you must remove the beam and return to the dipole as the
>front end will overload with the beam. I have even located poles with the
>dipoles unscrewed off the unit. It's that sensitive.
QST some years ago published an article describing a home brew
version of much the same thing.
It used an Aircraft Band AM receiver available at Radio Shack which
was installed inside a metal box for shielding. A 3 element beam was
then designed/built for the aircraft band freq range (~130-135mhz?)
and fed to the receiver thru a homebrew switchable attenuator to make
the signal strength manageable when the noise source is closer.
I used a wooden garden tomato stake for the boom of the beam, #6 ga.
solid copper wire for the beam elements, and mounted the receiver and
attenuator on the back end of the wooden stake. Not very elegant but
seems to work ok and has found several sources of power line QRN for me.
Here's another design from the CTDXCC web
site: http://www.ctdxcc.org/powerlines/
73 Phil NA4M
.--. .... .. .-.. _. ._ ...._ _ _
Phil Duff NA4M & Ann Duff
Georgetown, TX.
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