[TowerTalk] Triband stack - single tower arrays

[c penna]

Hi Mark, Assuming the tower is capable of taking the load  why not go for a
C36XR at full height which will give you a 10-40 capability with the option
of stacking below a C19XR for additional angles @ 10-20m.
Pity its Rohn 25. 73 Clive GM3POI
-----Original Message-----
From: KI7WX@aol.com <KI7WX@aol.com>
To: towertalk@contesting.com <towertalk@contesting.com>
Date: 15 September 1999 04:47
Subject: [TowerTalk] Triband stack - single tower arrays


>
>
>Before posing an unanswerable question, e.g. which array is a better
choice,
>let me thank the many folks who responded regarding K8UR type arrays and my
>80M verticle query.  Many helpful coments.  The gist of things were
verticle
>and sloper arrays for 40M don't make it compared to 2L shortened yagis at
>good heights.  With that in mind, I've reconsidered my tower plans and come
>back to an array that I designed about a year ago in preparation for our
move
>from So Cal to NC.  I think it's time to build this thing and see how it
>works, and will start digging holes after Floyd goes through.  Assuming we
>still have dirt to dig in that is.... In the meantime, I'm curious if the
>collective wisdom of the group can find any obvious flaws in this array
>design outlined below.
>
>Tower: I can go to 90 feet max with guys out to 72 feet but no much more
due
>to lot shape.  Wind here is 70 mph zone (Wake county), but folks that live
>here know that peak winds in hurricane season can be much greater. I
already
>have 70 feet of Rohn 25G so that is the tower choice.
>
>My first inclination was to do a pair of medium boom tribanders at 75 and
45
>feet.  Something like C19 or Skyhawks.  These have nice gain, F/B and with
>~22 foot turning radius they fit the area available very well (can go to
>about 27 feet turning radius without taking out more trees and I don't want
>to do that).  That array is fine, but doesn't cover 40M with a yagi so I'd
>need fixed wire beams or verticle arrays for that band.  Due to the
thickness
>of the trees, wire yagis are going to be hard to get up, and limited to
about
>60 feet or so above ground.  It would also be nice to get up closer to 1.6
>wavelenghts on 20M for the top antenna.
>
>Wanting to cover 10-40M on the tower and have a 2L rotating shorty for 40M
I
>have more or less settled on going to 90 feet with the 25G, guying at
>30/60/90 out to 72 feet.  Antenna choices will be Force 12 C4EXL at the top
>and C3Es at 60 and 30 on swinging gate type mounts.  Only real issues I see
>is limited bandwidth from the shorty 40 and the linear loading (I can live
>with that), the F/B and gain of the C3Es are less than the larger beams
>(compromise of cost, rotating size and windload), and it's getting very
close
>to having too much on the tower.  I can consider leaving off the low C3E,
but
>it'd be nice to have that on SA for DX events and for higher angle stuff in
>domestic tests.  I plan to guy with the anchors as suggested by Rohn
>(concrete deadman) and will use EHS wire with insulators/preforms to break
>the guys to non-resonant lengths.
>
>This seems like a great array for a single tower station on a medium budget
>but curious what do folks here think?  Any obvious miss cues in there or go
>for it?
>
>Cheers,
>
>Mark Curran
>KI7WX
>ki7wx@aol.com
>
>
>
>
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>


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