The losses in a 160 meter vertical antenna system are almost
completely controlled by what you do for the antenna's counterpole
(radials or counterpoise) and the electrical characteristics of the
dirt under the antenna. So the most important thing, the overwhelming
thing, you have not described at all. What are you connecting the
coax shield to? Describe the counterpoles for your two antennas in
detail.
73, Guy.
On Sun, Jul 8, 2012 at 10:54 AM, Steve Flood <kk7uv@bresnan.net> wrote:
> I have a 73.5-ft. wire vertical over a decent field of radials (about 60 or
> so, 50 to 120 ft. long).
>
> I have configured this vertical two ways over the past several years and am
> wondering if they are equal enough in radiated power that I should just use
> the simpler of the two.
>
> The configurations differ only in the topload "T", and the feedpoint
> matching.
>
>
>
> Configuration 1: 70-ft. flat horizontal topload wire with vertical
> attached at center. Feedpoint is 25+j0. Matching is through a 2:1 UNUN
> wound as per Sevick on a FT-150K.
>
>
>
> Configuration 2: 186-ft. flat horizontal topload wire folded back on itself
> to fit in a 60 x 6-ft space. (From the center vertical attachment point,
> each topload leg goes out 30 feet, turns 90 degrees for 3 feet, then turns
> back on itself another 90 degrees and goes 60 feet. Looks like a
> squared-off "S".) This resonates the antenna below 1.8Mhz with a feedpoint
> Z of 37 +j245. Matching is through an L-network. My intention was to
> increase radiation resistance and efficiency and move the current maxima
> away from the feedpoint and to the center of the vertical for lower takeoff
> angle.
>
>
>
> My question is how much am I losing in each system. Is the UNUN
> more/less/same loss as the L-network?
>
> I run 1200 watts and the L-net components are sized adequately. A 1-minute
> keydown produces no arcing, and the coil and cap do not get hot.
>
>
>
> Thanks,
>
> Steve KK7UV
>
>
>
>
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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