[Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

[Don Wilhelm]

David,

I have seen several responses that suggest changes to your antenna 
setup, but not one that I can "warm up to".

The choice of a 1:1 balun vs. a 4:1 balun depends on the feedpoint 
impedance and has nothing to do with the fact that the characteristic 
impedance of the ladder line is 450 ohms - the impedance at the shack 
end of that feedline is what is important. If you do not understand what 
is going on, I direct you to the antenna article on my website 
www.w3fpr.com,

I would strongly suggest that you measure the electrical length of the 
feedline plus the length of one side of the radiator for all bands of 
interest.  Avoid those sum lengths that are close to a multiple of a 
half wavelength.  Most autotuners do not have the range to work into the 
high impedance presented by a half wavelength - that goes for 1/2 of a 
dipole (plus feedline) as well as for an end fed antenna.

73,
Don W3FPR

On 10/26/2012 10:23 AM, David Bunte wrote:
> Ron -
>
> This is not an area where I have much experience, but with 450 ohm ladder
> line I would have thought you would use something other than a 1:1 balun.
>
> A few years ago I experimented briefly with an 80 meter dipole, fed with
> 450 ohm ladder line.  I tried it with a 1:1 balun and with a 4:1 balun.  An
> LDG AT-7000 tuned it very easily on 80 through 10 meters while using the
> 4:1 balun... but had trouble on some bands with the 1:1 balun.
>
> Dave - K9FN
>
>