[SCCC] WARC Antenna on a single tower for the contester?

[Dave Hachadorian]

If there is any interaction among the antennas, it will show up 
as degraded front-to-back ratio on the yagis.  You can do a 
simple test of f/b ratio, described here:
http://lists.contesting.com/archives//html/Towertalk/2007-06/msg00508.html

If the f/b is ok, you can be sure that the gain and pattern are 
also ok.

f/b is the most sensitive interaction detector.


Dave Hachadorian, K6LL
Roellbach, Germany





-----Original Message----- 
From: Timothy Coker
Sent: Tuesday, April 19, 2011 9:05 PM
To: CQ Contest ; SCCC
Subject: [SCCC] WARC Antenna on a single tower for the contester?

I currently have a 55' crank up tower with 15' of mast sticking 
out above my
thrust bearing. I have an 80m inverted-v a few feet below the 
thrust
bearing, a F12 C31XR right above the thrust bearing, and a 
Cushcraft XM240
12' above the thrust bearing. I do not have the property for a 
second tower.

I love being serious during domestic contests and enjoy having 
fun during
world wide contests. I enjoy DXing during the interim of the 
contests that
catch my attention. However, my main interests by far are 
contests.

I put up a Cushcraft A3WS in between my C31XR and the XM240 with 
all of the
booms being placed in parallel with each other. I have about 6' 
of
separation in between each of the yagis. I did this because I was 
still
working on getting 100 DXCC entities on 30/17/12, which I have 
now
accomplished. I also knew it would help me build up my DXCC 
Challenge totals
so that I could hit 1,000 for the lumber. That is done. I lastly 
did it with
the fact that I need 67 more for #1 Honor roll, something I am 
still working
on.

The question I have is whether having a three element yagi 
sandwiched in
between my contest antennas is really worth it when my main 
interest lies in
contesting. DXCC stats are cool and I do enjoy getting the new 
band
entities, but it doesn't give me the same thrill as trying to 
place well in
a contest. I have no idea how little or how much interaction may 
be
occurring, but something has to give when extra, un-needed metal 
is around
our antennas during a contest.

The risk of interaction during a contest versus the reward of DX 
during the
off times is at question. While taking the A3WS down would be a 
personal
choice for my own interests, I imagine there must be other 
contesters out
there who have gone through this thought process? Maybe other's 
on the
reflector can weigh in on whether I am thinking short term and 
not long term
as my DX oriented Elmer would tell me. He's only interested in a 
59(9) and
he's out of a pile up... while I want every last bit of energy 
oriented
toward holding a run frequency.

My initial steps towards removing the WARC yagi would be to leave 
the driven
element up as a rotatable dipole mounted in-line with the booms 
of my C31XR
and XM240 so as to minimize any potential interaction. My next 
step would be
to eventually replace it with a rotatable 80m dipole at the same 
point on
the mast.

Am I over analyzing here?

73,

Tim / N6WIN.

Checkout 
http://s192.photobucket.com/albums/z90/tjcoker/N6WIN%20LM354HD/ 
for
my tower install project, password is "73".
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