When I started to build my 160 station in NH in 1979, my tower was shunt
fed, 70' high and had a 18' Rohn mast at the top. It worked but I was always
in the middle of the pack in pile-ups.
In the early 80's, I secured more tower and decided to add another four
sections taking the tower to 110'. Additionally, I added a 40-2CD and A4 for
top loading. I never did the calculation but electrically this must take me
to over 130'. I also was able to find a LOT of wire at a hamfest and I laid
down almost 20,000' of radial wire.
I used a unipole feed based upon Laport's work and a QST article by DeMaw
and W5RTQ aka K6SE. I ran a 12" wire cage spaced three feet from the tower
to the top and fed the wire with a step-up L network; series L and parallel
C.
The proof is in the results in that this antenna has served me well for the
last thirty years and allows me to work my share of DX.
Due to corrosion, animals and forest growth, my radial field is probably the
weakest link to my antenna at this point.
I did try to use this antenna for 80 and as Tree has pointed out, it is
closer to a half wave and has a far too low takeoff angle.
--
Craig Clark, K1QX
Radioware
PO Box 209
Rindge NH 03461
(603) 899 6957
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