[CQ-Contest] antenna advice

[Art Boyars]

I've had good luck (see below) with a 200 foot dipole, built to fit the
available trees..  It's fed with ladder line.

K3UA -- always loud here -- makes do with an 80M dipole, even on 160M.  (He
consistently crushes me in SS CW SOLP.)

N3QE used to rely on a single dipole, with clip-lead matching networks to
change bands.  (Look at his results.  Amazing!)

The problem with a non-resonant dipole (actually, any antenna not matched
to its feed line) is that matching it can be a challenge. The impedance at
the shack end of the feed line can vary wildly from band to band, or even
over any one band, and will vary with the length of the feedline.

My dipole runs over and through its supporting trees at each end.  The last
25 or 30 feet on each end comes down vertically. The ladder line hangs down
to form a half-loop between the antenna and the house.  The up and down
motion of the bottom of the loop is a good wind speed indicator.  The
ladder line runs under the eave of the house, parallel to the rain gutter,
for about 25 feet, then bends down about 10 feet to the entry point.  The
length of the ladder line is carefully chosen to match the physical
configuration; nothing to do with antenna matching.

>From the bottom end of the ladder line I have 50 feet of coax to get
through the basement wall and to the rig.  The excess length of the coax is
coiled to make a balun where it connects to the ladder line.  Why a balun?
Because antenna lore seemed to think it was a good idea.

I used that configuration for a few years, then added another balun inside
the shack to improve the matching.  The second balun is 22 turns of RG-58
on an oatmeal box.

"To improve the matching" -- I would not bother to try analyzing my antenna
system to predict the impedance seen by the transmitter (on six bands!).  I
tried using an antenna analyzer to measure the impedance, but had a lot of
QRM from the nearby 50KW AM BC station on 1500 KHz.  Instead, I use a
practical, measurable criterion: Can the auto tuner in my TS-850 match the
antenna system on the contest bands?  The first time I tried it, it
worked.  That's plain luck  (though I did have a plan to sort things out if
it did not work).

The luck is very sensitive to my particular configuration.  One time I
replaced ancient the thru-wall coax with new RG-8, and coiled the first
balun inside the shack instead of at the junction with the ladder line.
That messed up the matching, so I restored the original configuration.
Later, I experimented with the oatmeal balun.  It seemed to make the auto
tuner's job easier, so I kept it.

So, use whatever dipole you can get up.  Feed it with ladder line or
open-wire line.  Get a wide-range antenna tuner, or build matching
networks.  Fiddle with the feed line length. See what works.  Make QSOs.
Have fun.

73, Art K3KU

On Thu, Sep 13, 2018 at 7:11 PM, N9GG via CQ-Contest <
cq-contest at contesting.com> wrote:

> Advice sought for simple wire antenna installation...
> We just put up a center fed wire antenna that loaded up OK on 30, 20, 15,
> 10 for some reason, but poorly on 40 and 80. An external manual tuner
> helped out on 40 but not 80.
> I want to put up a SINGLE WIRE ANTENNA for 80 to 10, or close to it. 20 or
> 40 is usually where I wind up. Since the ropes are up, center fed is what I
> want.
> This will be for a TS-590SG for a little bit of low power unassisted CW
> contesting.
> I've had so many antennas and radios in the past, I can barely remember.
> Please give me your two cents.
> Thanks and GO FRC!!
>                                                   Bob N9GG
> _______________________________________________
> CQ-Contest mailing list
> CQ-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/cq-contest
>