Bill,
I have a wire element 80m 4-square that is suspended from two catenary
ropes from the top
of my tower (125 ft.) positioned to the South of the tower. Closest 2
elements are about 90 ft. from
the tower. I also use the Comtek box.
>From what I've experienced I wouldn't worry about broad-banding the
elements. Initially, I switched
in some linear loading when going from SSB to CW. This arrangement was
abandoned when I didn't
experience any TX or RX detriment by just using it without the loading
all the time. Realize that the
Comtek phasing box will broadband the array by absorbing any mismatch
in the 100W port resistor.
So your rig/amp will see a low SWR even when moving from the CW band
to SSB band. (Note:
I have the elements tuned for midband at 3650 KHz.)
Also realize that the optimum element spacing is lost when you move
away from the design frequency.
So the bottom line is that the array will always be a compromise and
you'll never achieve an ideal
antenna. But it is far and away superior to the alternative. If your
final design is a little too close to
your tower or your land slopes too much, live with what you're capable
of putting up. Besides, the KH6
callsign is good for another S-unit.
Regarding AL elements vs. wire. The AL elements will more than likely
require one or two levels of guying
whereas the wire elements will not. This may not be a consideration
for you but for me I didn't want the guy
wires getting in the way of other backyard activities.
Good luck with the project.
Kris N5KM
---- original message -----
Date: Tue, 8 Mar 2016 20:37:58 -0500
From: cqtestk4xs@aol.com
To: TOWERTALK@contesting.com
Subject: [TowerTalk] 4 square for 80
Message-ID: <1535905fdc4-1848-17a4d@webprd-a22.mail.aol.com>
Content-Type: text/plain; charset=utf-8
I've always had real high towers and no restrictions on the amount of
towers I could have. Out in KH6 it is different....one 90 footer on
one plot of land. Since that is a hard and fast rule, the quad loop
systems for 80 meters I've had on the mainland won't be nearly as
effective...according to HFTA. I really can't get enough height for
them to be real barnburners.
So....I've decided to try a four sqaure. Soil here is clay and stays
wet most of the time, plus I have enough room to lay out a good radial
system. The grouind undulates a bit and slopes about ten feet or so
in the direction of the Pacific which is about one mile away. The
antenna site sits at 1100 feet so the slope once it gets off the
antenna site is great...about 1 foot drop for every 5 feet of
horizontal.
I've decided to go the Comtek route for the control.
Several questions:
First, any thoughts as how the terrain where the antennas are located
will affect operation? Also, any thoughts on how the big slope from
the antenna location to the ocean will affect the signal. On HFTA it
is a big help on 80 with dipoles etc. but I'm not sure how it will
affect a vertical system.
Second, I have two ways to go on the construction of the verticals. I
can fabricate aluminum full size quarter wave verticals which of
course will provide decent bandwidth, not as good as four towers, but
better than wire verticals. One problem is the location. The closest
element would be about 30 feet away from the tower whcih has seven
Yagis stacked on it. The other three verticals are about 70-90 feet
away(all to one side of the tower). Guy wires are not the issue
(Phillystran), but the tower is. I have no way to model this thing so
it's pure guesswork how much the tower and other antennas (40-6
meters) will affect the signal.
Last, I could run four ropes from the tower at 84 feet and make wire
verticals in a four square pattern around the tower. To increase
bandwidth I am planning on running the vertical wires in a "cage".
from what I've read that is the way to increase bandwidth. The
problem with this of course is the proximaty to the tower. All four
wires would be within 33 feet of the tower and the seven HF/VHF
antennas. So, the vertical system would "see" the seven antennas and
the 90 foot tower. Again it is guess work on my part as to what
effect they would have on the four square. No guy wires to consider
since I am using Philly. The other issue is I am afraid the 80 meter
verticals would screw up 20 meters on my triband stack.
My gut feeling is the aluminum 1/4 wave verticals located slightly
away from the tower would be less affected by the tower/antnennas.
However, for ease of construction I really would like to do the
vertical wires around the tower.
This is my first foray into four squares so I would really like some
opinions from guys who have experience in these matters.
Mahaho for the help!
Bill K4XS/KH7XS
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