[TowerTalk] Beam Interactions

[Joe Subich, W4TV]

Look up gamma matching a yagi boom for 40 meters.  Both K4RO and N4KG
have written articles on it over the years.  N4KG's appeared in one of
the ARRL antenna compendiums (I think), K4RO's info is on the web:
http://www.k4ro.net/tcg/pix/40boom.html

Use your TH7 and you will not have to deal with added wind load or
increased interaction if you move the A3WS closer to the TH7.

73,

    ... Joe, W4TV


On 2014-08-13 9:34 PM, Don wrote:
> Wow, what a great site, every day I see some new idea or learn something
> new.
>
> Until I moved from Portland to the OR coast, the beams I've had up have
> been single triband beams. In my present location,however, I installed a
> Hy-Gain HG70-HD tower, topped with an old TH7DX 10/15/20 tribander, and
> some 8 feet above it, a Cushcraft A3WS for 12/17. The mast is 20 feet
> and topped with a 16 foot Decibel 2M monopole. The tower and beams have
> withstood winds up to 80 MPH without damage, a velocity in gusts not
> uncommon during the winter. The tower is usually only up 2/3 of the OA
> possible height.
>
> Setting that stage, I was following the discussion re 40 M beams with
> drool. Then I remembered I have an old KLM 7.2-1 rotatable dipole
> sitting in storage and thought why can't I incorporate that with the two
> beams.  I had always hoped back 20 years ago to be able to find a second
> KLM and make a 2 el as KLM (then in CA) suggested and gave specs on in
> their manual. Didn't happen.
>
> My current thought was to drop the A3WS down to maybe 3-4 feet above the
> TH7DX (minimal interaction) and mount the 40M rotatable dipole at the
> mast top, above the A3WS and below the 2M monopole. I'm willing to live
> with some degradation since at my age (78,) I'm not likely to be putting
> up more towers and antennas, regardless of how great the location is.
> The mind is willing, the body ain't. It is all I can do to just do the
> layover of the tower for antenna work.
>
> So, the question - is the latter idea feasible? Does anyone have
> suggestions on a better arrangement?
>
> Don W7WLL
>
>
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