what you want to build is a bandpass/reject tunable filter.you can tune it
to notch out the offending bcb station while letting everything else through

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"Michael Lawson" wrote in message
...

"Michael" wrote in message
...
I just wanted to share the results an antenna experiment I did
tonight. In
the rain, no less.

The antenna was simple. 300 feet of solid core 20 gauge copper wire.
I ran
it from the 500 ohm connector of my R-75, out of the shack and all
the way
into the back yard. The yard extends about 200 feet, so I had to
double the
wire back in the direction of the shack for 100 feet.

No mater what I tune the dial to, I'm getting splashed from the
local 50
kilowatt am stations. The preselector doesn't clean it up either.

Every time I exceed 200 feet of wire, I have the same problem.

Weird...

You might want to put a high pass filter in place between
the longwire and the preselector, nulling out the AM band
as much as possible before the preselector. When I lived
closer to the antenna for WCKY 1530, I homebrewed one
that got rid of the AM BCB band. You can find the schematics
for one in the ARRL handbook or one of Joe Carr's Tech Notes
on DXing.com: http://www.dxing.com/tnotes/tnote06.pdf

--Mike L.


--Mike L.

Wrapping the antenna wire back on itself as you do with "Frankenstein"
or forming the G5RV into a quasi-rectangle is liable to result in an
antenna that performs no better than a single wire as long as the
maximum dimension, especially in directions in the plane of the shape
and perpendicular to the longest side. However, I have heard people
extol the virtues of a bedspring as an antenna - an extreme example of
winding on itself. Of course, the more wrapping about you do, the more
the wire approaches a solid, the limiting condition. Looking at
Frankenstein, I'm reminded of a fat dipole, something like the
"butterfly" antenna element frequently used at UHF. If you connect the
free end and all the criss-crosses to the feed point, it certainly
would be. With an overall length of 82 ft per the diagram, it would
probably have a major lobe pointing straight up around 6 MHz. Height
above ground will control the gain at lower elevation angles while the
slight inverted Vee shape will broaden the lobe towards the narrow
ends. At higher frequencies, the major lobe will divide into smaller
lobes at lower elevations. The fatness factor will moderate the
impedance range of the antenna around its 6 MHz resonant frequency.

I rather doubt that either your G5RV or the Frankenstein are great DX
antennas, the way they are laid out. Both are liable to favour short to
medium distances below 10MHz and are unlikely to provide the necessary
low elevation angle sensitivity for really long DX in all desired
directions at any frequency. I think you would be better off with less
wire, laid out straight to take advantage of directional properties.
Three mutually orthogonal antennas with a switch would be great. Attach
a vertical antenna, say a CB whip or longer, to your chimney, as high
as possible, for one. Run two independent dipoles in a cross pattern,
even an X like you have would be a good compromise, from the chimney.
Then you can switch among them for best reception - often one will
stand out above the others because of direction, polarisation,
frequency, and arrival angle of the incoming signal will best match one
antenna.

Regards,
Tom