[Elecraft] Suggestions needed - antenna to tuner

[Bob McGraw K4TAX]

Chris;

Add or remove about 6 ft of the open wire line.  See if this helps the 
17M issue.

I personally don't like the idea of using a 4:1 balun and much prefer a 
1:1 current balun.  With the 4:1, without measuring the Z on the coax 
side, it may be the Z presented to the tuner is very low and thus 
outside the range of the tuner.   Additionally, it is most likely with 
almost every ATU, the greatest loss occurs when the Z is low to very 
low.  Hence my reason for using a 1:1 and not a 4:1.

73

Bob, K4TAX


On 2/13/2018 7:55 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.
>
> Any suggestions for how to get it to tune on 17?
>
> 73
> Chris - K1AY
> Punta Gorda, FL
>
>
> On Mon, Feb 12, 2018 at 12:16 PM, John W2XS <jm416 at optonline.net> wrote:
>
>> I replaced my Johnson Matchbox with a Balun Designs tuner balun. The
>> biggest
>> benefit is that the K3 ATU remembers the settings from band to band so the
>> QSY is very rapid. I love watching the DX spots come rolling through on my
>> N3FJP logging program and clicking on them to QSY to that frequency and not
>> have to tune up again. I use it on 80 through 6 meters with an 80m doublet
>> fed with KW ladder line (300 ohm).
>>
>> My recommendation is to keep the piece of coax from the balun to the rig as
>> short as possible.  This is to minimize loss since that line will most
>> likely be highly mis-matched on most bands. There was a QST article not
>> that
>> long ago which detailed the losses in that situation and I was surprised at
>> how high they were.
>>
>> I once had an MFJ balanced RF Ammeter and made measurements of the JMB vs.
>> the balun and they compared favorably.  DJ0IP (referenced earlier) has
>> kindly put those measurements on his website. (This is in the FWIW
>> category!)
>>
>> I have not tried to substitute the tuner balun with another type but that
>> might be a future experiment.
>>
>> 73, John W2XS
>>
>>
>>
>> --
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