One caveat with regard to using HFTA for planning stacks. HFTA
overstates the stacking gain for narrow spacings. Choose your stack
spacings based upon other more commonly accepted criteria or model it
with some version of NEC before loading the stack into HFTA.
73,
Dave AB7E
On 6/18/2014 9:35 AM, john@kk9a.com wrote:
69 feet and 138 feet are usually very good heights for 20m. I use similar
stacking heights and I have numerious 20m contest plaques. I have never
used HFTA, does it model stacks properly?
A 200' high 10m beam can be a very good antenna however there are many
nulls so there will be times that is a poor antennas. This should not be
your only 10m beam.
John KK9A
To: "Cqtestk4xs@aol.com" <Cqtestk4xs@aol.com>
Subject: Re: [TowerTalk] Site Elevation and TOA
From: Jorge Diez CX6VM <cx6vm.jorge@gmail.com>
Date: Wed, 18 Jun 2014 10:45:06 -0300
Really is nice to see HFTA suggestions
For a project to put two 20M5 in a stack, I was told by several friends to
put
them at 69/138 ft
HFTA show that this is not the best height and they must be not to high,
59/118
seems to be better
Anyway the practice show me that high antennas are good:-)
Most of the people told me that a 10 mts antenna at 200 ft hight will not
work,
but really this antenna pay off all the work
So now, about the 20 mts stack project, I am in doubt if I need a 118 or
138 ft
tower, not sure what to do :-(
73,
Jorge
CX6VM/CW5W
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