[Elecraft] Suggestions needed - antenna to tuner

[Chris Hallinan]

Thanks, Don,

Yes I understand the basics - the doublet is not typically used in a
"matched" configuration, thus the need for the tuner.  If I understand
correctly, it can present from very low to very high impedances to the
tuner.  I will try a 1:1 and/or adding some wire length.  Also, as I
mentioned in my previous post, I've been wanting to get up on the ladder
and scan it with my Array Solutions antenna analyzer to see what it really
presents to the tuner.  That may help me understand what I need to do.

73,
Chris - K1AY

On Tue, Feb 13, 2018 at 9:13 AM, Don Wilhelm <donwilh at embarqmail.com> wrote:

> Chris,
>
> Try a 1:1 balun instead of the 4:1.  You are matching the impedance seen
> at the shack end of the feedline, and that can vary from very low to very
> high.
> The impedance you have to match is NOT the characteristic impedance of the
> feedline.  The 600 ohm line simply acts as an impedance transformer.
> The only time you will see a 600 ohm impedance at the shack end of that
> feedline is when the far end is terminated by 600 ohms, and I suggest that
> is not true of the feedpoint impedance at the antenna.
>
> 73,
> Don W3FPR
>
>
> On 2/13/2018 8:55 AM, Chris Hallinan wrote:
>
>> I have a very similar setup.  K3 -> KPA500 -> MFJ 994BRT 600W autotuner
>> mounted remote -> Balun Designs 4:1 -> 600 Ohm open wire line to 80 m
>> doublet.
>>
>> It works fantastic on 80-20, but will not tune better than about 2:1 on
>> 17.  I cannot use the KPA500 on 17 because the SWR is too high.  Nothing
>> I've tried works.  I'm wondering if it is simply the tuning
>> range/resolution of the MFJ-994BRT?  I like the idea of remote mounting,
>> as
>> I have only a couple feet of coax between the tuner and the balun, thus
>> minimizing SWR-related feedline loss.
>>
>


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