I have suspended a T antenna from two 50' foot towers and a 50'drop
wire...adjust the T to give a good match on 1.8 against ground. (A few
radials will do. Them with two additional drop wires on insulators off
set on the T one cut to length for 3.5 and angled to the same feed
point...and another for 40 meters....You can get some on 160-40 that
preforms well with a modest ground radial system. I made mine from THNN
wire and even put in some CAT 5 Cables of various lengths. Not the best
RX antenna here but it works well on TX.
Herb, KV4FZ
On 11/4/2016 12:18 PM, Tom Osborne wrote:
Hi Kirk
To get the feel of a vertical, could you try shorting the feedline of the
dipole together at the shack end and load it up as a top loaded vertical
(with some radials of course)?
Might be better than a really short vertical. 73
Tom W7WHY
On Thu, Nov 3, 2016 at 10:41 PM, Kirk Kleinschmidt via TowerTalk <
towertalk@contesting.com> wrote:
Hi, gang,
I'm in a bit of a race against the clock (the winter clock), and I'm
trying to get a vertical up in the back yard that might be useful on
160-40. (Never used a vertical before, but I wanna.)
Assume that I have plenty of 50-foot radials or a 500-square-foot
galvanized ground screen (Rochester reportedly has excellent ground
conductivity).
My other antenna (until Spring, when towers can go up) is a 102-foot
doublet fed with open-wire line, up about 40 feet (not exactly killer on
the low bands for DXing). The vertical doesn't have to be "the final
design," as it can be changed in the Spring, but it does have to be quick,
as my pre-winter window is closing soon.
I am thinking about feeding it with an SGC or Icom autocoupler for ease of
multibanding, but I would consider making dedicated feeds for various bands
(100 W max for this first winter season).
The main vertical element will be a 30-foot length of aluminum irrigation
pipe, either 3 inches or 6 inches in diameter. I'm not sure yet, as I don't
know which will be available to me. The 6-incher is 70 miles away, the
3-incher is 120 miles, and I have to transport these pipes with a Ford
Focus and an 8-foot utility trailer (and lots of back roads).
30 feet is close to a quarter-wave on 40, of course, and I can add a
top-mounted loading coil. a top-mounted trap, a capacitance hat near 30
feet (like a 20 meter quad loop mounted parallel to the ground), or a
22-foot fiberglass "whip" with heavy-gauge aluminum wire inside (or a
combination).
Without presenting "too-crazy" impedances on one band or another, is there
a "magic formula" for something like this, or is the frequency span just
too great?
As always, thanks,
--Kirk, NT0Z Rochester, MN
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
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