In a message dated 96-12-01 23:55:09 EST, you write:
>Ijust moved and will erect my tower next month, it's 60 feet high.
>I"m planing to put on it, new antenas that wil be a similar to a TH6 and a
>402CD.
>The 6 element triband it'll be on top and the 40 meters just below, but the
>questions are:
>what is the distance between the antenas?
>I'll be able to turn the sistem using a HAM-IV?
>Any comments and sugestions wil be welcome!
Hello, Amadeu --
Assuming that you are building the tower and antenna installation to the
appropriate wind loading specifications from the manufacturer and that your
mast will survive the same situation, it's been my experience that anything
above about 6 feet (2m) will work. Many antenna manufacturers recommend 8-10
feet. I'd be curious to see what computer says about the stacking distance
and interaction. My experience has been with these antennas that the SWR
will go up as the antennas get closer together but I don't have any comments
on what is happening to the patterns. Anyone have more specific information
on this topic?
The Ham IV will do the job but will probably have trouble turning the
system in a brisk wind due to not enough starting torque. A T2X Tailtwister
or large Create or Yaesu will do it more comfortably. If you have the Ham
IV, by all means use it - you may be lucky - hi.
BTW, this is a very competitive combination of antennas for contesting.
I agree with your proposed stacking by putting the 40M (larger) antenna
at the bottom. It is the one that will need the most maintenance over time
and being at the bottom makes it much easier to remove. An additional 8 feet
of height on 40M is only 6% of a wavelength; perhaps not enough to justify
installing it at the top of the mast to get additional heighth/performance.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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