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Old May 24th 04, 04:52 PM
Larry Loucks
 
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The LDG tuners will tune a fairly large range and should work in your
application. Look at the QST reviews of a collection of auto tuners for
details. Are you using a balanced feedline? If so, you should use a
1-1 or 4-1 current balun to make the connection to the tuner. If you
are using coax feed use a 1-1 current balun at the feed point.

Knowing just the SWR does not give you the feed line input impedance
which you need to know to understand if the tuner will match. You can
use Eznec to tell you the feed point impedance and a program like TLW to
model the input impedance and calculate the L and C values for a L
network tuner (LDG is a L network tuner). Of course, if you can borrow
an analyzer you can just measure it. Depending on the feed line length
you may just be unlucky and a change in the feed line length will
transform the impedance into something that will match. TLW will help
you figure that out.

I use a LDG RT-11 to feed my 136' dipole and it will match on 160
through 10. I use a length of 450 ohm ladder line to a 4-1 current
balun to the tuner and of course coax to the radio. I selected the
length of the ladder line to insure the match.

Larry

Greg wrote:

I recently acquired an ldg lz 100 and hooked it up as soon as I got
it. The dipole I have now will tune with a manual tuner to below
1.5:1 on 40m-10m. The autotuner won't tune to below 1.5:1 in any
band. Am I doing something wrong or did I just not get a decent
tuner. I oftentimes won't even get an SWR green light to show it has
tuned and when I do, the SWR is high. Should I put a balun on or
what? The dipole is 66 feet long in my attic... but as I stated, it
tunes awesome with the manual tuner. If you want to email me, please
email to The email here is incorrect.