Try it with what you've got, you have nothing to lose and it could work
fine. Since it sounds like you don't have a link coupled (ala EFJ Matchbox)
or balanced-balanced tuner, then you'll probably need to use a balun at the
tuner. Some will say a 1:1, most tuners use a 4:1, and you might need a
higher ratio depending on the impedances of the antenna + line (and you
can't predict these very well until you try them in your real world).
You'll know you'll need the balun if you get RF feedback in your rigs, RF
burns on your lips, can't get a good latch from the tuner, etc.! Try the
setup with low power first, and if you have success, gradually increase
power and see if things change.
If you have troubles with pickup & radiation from the feedline, you may have
to take further steps to better balance it.
Suggest you read some of these articles on these links, they describe your
situation better than I can:
http://www.cebik.com/radio.html
http://fermi.la.asu.edu/w9cf/articles/balun/index.html
http://www.somis.org/bbat.html
73
Dan
K0DAN
----- Original Message -----
From: "Merlin-7 KI4ILB" <merlin-7@sc.rr.com>
To: "k0dan" <k0dan@comcast.net>; <TOWERTALK@contesting.com>
Sent: Friday, February 10, 2006 9:04 PM
Subject: Re: [TowerTalk] ladder line vrs coax
> I was not planing on using any coax at all. My antenna tuner has
conections
> for bal. line.
> Is there a problem using this connection without a balun?
> Also the tuner is grounded.
>
>
>
> > I'd vote for a flat top dipole as high as you can get it, with
ladderline
> > feed (or a variety of loops, as others have suggested). 300 ohm or 450
ohm
> > line will be an easier match than 600 ohm. You can bring the ladderline
to
> a
> > balun, then your tuner. You may have to experiment with different
lengths
> > for the ladderline...1/2 wavelength feedline at lowesat freq is ideal
> (allow
> > for velocity factor), avoid 1/4 wavelength. Also, once in the shack,
try
> to
> > keep your coax lengths as short as possible as well.
> >
> > A grounded tuner is less than optimal for keeping open wire line
balanced
> (a
> > balanced or link coupled tuner is better for this, but you might get
by).
> >
> > Stray pickup by the ladderline should only be a problem if it is
seriously
> > out of balance. If the currents are equal & opposite in both legs, the
> > feedline line should neither radiate nor pick up signals. Make sure both
> > dipole elements are the same size and heigh above ground. Avoid
proximity
> to
> > trees and other objects. Try to have the feedline drop vertically from
the
> > center of the antenna, don't let it run parallel to or get close to the
> > dipole elements. There is plenty on this topic online and in the various
> > handbooks.
> >
> > Goodluck & 73
> > Dan
> > K0DAN
>
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>
>
>
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