Posted by
Don Wilhelm-4 on
Jun 05, 2010; 11:14pm
URL: http://elecraft.85.s1.nabble.com/K2-ATU-and-43-ft-Vertical-tp5144100p5144202.html
Paul,
That is not an easy question to answer, and for your particular case, we
do not have enough facts.
It would be necessary to know the configuration of the radial field for
that vertical, then plug that information into an antenna modeling
program to find the impedance at the feedpoint to the antenna for any
frequency of interest.
After that, you must specify the feedline (both the type, the velocity
factor and the length), as well as the details of any matching network
at the base of the antenna. It is not a simple question, and the right
answer is "maybe"
Once all that information is available, the feedpoint impedance at the
shack end of the transmission line can be calculated.
With the feedpoint impedance at the shack end known, then the L network
values to match it to 50 ohms resistive can be calculated. A look at
the specifications for the KAT2 indicate the maximum inductance
available and the maximum capacitance. If the required inductance and
capacitance for the calculated L network is less than the maximum values
available for the KAT2, then the answer is a definite yes.
A 43 ft vertical is a bit short on 80 (but not impractical). There was
a recent article in QST with a tuner at the base of a 43 ft vertical to
provide a good match on 80 and 160. A 43 ft vertical is a 43 ft
vertical, and the major difference between them is the effective
electrical diameter of the radiator, the mechanical construction, and
the price - take your pick. There is no magic in the 43 ft. length
except it is practical to erect without a large crew tugging on guy
lines, many can simply be "walked up".
73,
Don W3FPR
Paul Huff wrote:
> Does anyone have any experience with trying to match one of these 43-ft
> verticals, that are being offered by several manufacturers, using the K2s
> internal ATU? Is it able to find a match on 80-meter CW? Are there any
> particular brands of 43-ft verticals that you like or don't like? Most of these
> verticals that I have seen are in the mid to upper $300 range, except for the
> fiberglass one from S9 Antennas. Any opinions on that particular antenna?
>
> Thanks in advance for any information offered.
>
>
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