The hybrid controllers are designed to work with the impedance of full
sized verticals. You should be able to change the impedance of a shortened
vertical with a match or different coax but I am far from being an expert.
The best way to see the effect of the tower is to model it. When modeling
80m verticals at my station I found that a tower in the middle was not as
bad as one off to the side where the pattern became very skewed.
Verticals are very sensitive to other vertical structures and in an ideal
world you would have the array hundreds of feet away, however most of us
make compromises. Look at K9RS's vertical presentation:
http://gofrc.org/pdf/multi-element_lowband_vertical_6.pdf
John KK9A - W4AAA
To: TOWERTALK@contesting.com
Subject: [TowerTalk] 4 square for 80
From: Bill via TowerTalk <towertalk@contesting.com>
Reply-to: cqtestk4xs@aol.com
Date: Thu, 22 Sep 2016 15:59:46 -0400
This will be my first foray into the world of 4 square xmit antennas.
Plans are to make the elements from wire, suspended from the tower by rope at
about 80 feet. Due to the slope of the ropes from the tower to the
ground, the
elements might wind up a little short. Plans were to T-top them running the
wire parallel to the rope. The elements might be around 60 feet so it would
not be that hard to T top them to make up the extra length needed for 1/4
wave.
I had planned to do the following: Have an elevated ground system a 1/4 wave
radials running from the base of each vertical. Height of the system
would be
10 feet. Radial system would consist of 16 radials for each vertical
using the
Comtek 4 square system to control it.
In talking with the guys at DX Engineering about the planned setup I was
given
the not so good news.
First, I was told you CAN NOT use an elevated ground system with the 4
square.
Second, I was told the tower would interfere with the system. They said I
would have to cage the tower to make it "invisible" to the system. Caging
the
tower is impossible since it is a rotating tower and the cage would wrap
on the
stacks mounted on the tower.
Was he right about all of this?
I can not put up another tower due to tower restrictions (one tower allowed),
so the only way I can get enough height to suspend the wires is to use the
tower I have. The county thinks anything 60 feet high constitutes another
tower, so I can't make aluminum verticals. No trees around either for
supports.
I really am in a bind for 80 if all this is true. An inverted Vee at 80
feet
is far inferior to the 4 square I had planned.
Ideas and thoughts on this?
Bill K4XS/KH7XS
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