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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