[Elecraft] KX3 connection to doublet question

[Don Wilhelm]

Stan,

The transmission line acts as an impedance transformer, so no one else 
can duplicate the performance and matching capability of your antenna 
unless you specify the feedline length.

For the same reason, if you extend your 450 ohm line, you may create 
some impedances that could be difficult to match.
A few sessions with the TLW software (see www.ARRL.org) will allow you 
to experiment if you know the impedance at the antenna feedpoint.

A common mode choke at the end of the feedline will help with balance 
and keeping RF out of the KX3.

73,
Don W3FPR

On 4/20/2015 11:42 AM, stan levandowski wrote:
> For several years, I've been using my multiband non-resonant 94' 
> doublet, fed with a short run of 450 ohm window line, to a remotely 
> mounted SG234 autocoupler and then a 25 foot run of 50 ohm coax to my 
> KX3.
>
> Has been working with perfection; no complaints, except I cannot 
> operate QRP below 3 watts because that's the minimum RF required for 
> the autocoupler.
>
>
> Now, if I wanted to extend my 450 ohm line and connect it directly to 
> the KX3 and use the KX3's internal tuner, would there be any benefit 
> in a 1:1 isolation balun at the KX3?
>
>
> I can't think of any reason this would be necessary except as a 
> transition from the window line to a convenient coax output to the KX3.
>