[Elecraft] Slightly Unbalanced dipole?

[Vic Rosenthal]

I’ve measured common mode current when feeding a balanced line with a good DX Engineering 1:1 balun and an unbalanced tuner, versus a real balanced link-coupled tuner (Johnson Matchbox). To my surprise, the currents are closer to equal with the unbalanced tuner and the balun! But the Matchbox seems quieter.
More investigation needed...

Victor 4X6GP 

> On 14 Jan 2019, at 2:44, Al Lorona <alorona at sbcglobal.net> wrote:
> 
> You guys keep talking about coax-fed antennas. Yes, although it may be easy to wind coax around a toroid and put it up at the antenna midpoint, that's not so easy with open-wire line. This discussion was very coax-centric and I wanted to open your minds that not everybody feeds their antenna with coax.
> 
> Balanced feedlines ("window line" or "open-wire" line) can have significant common-mode current. They're not immune to the effect. (I know you know this; I'm saying it for the benefit of all.) A device with high common-mode impedance, located right at the output of the tuner, suppresses common-mode current on a (balanced) feedline. That's it's purpose.
> 
> I'm in agreement with you about the 1/ cause of common-mode current and the 2/ cure for it. I'm simply saying that for convenience's sake, consider putting the choke at the tuner output.
> 
> A choke with high Z to common-mode current, external to the tuner, in a non-conductive box, with as short a connection to the tuner as possible, does quite well at suppressing common-mode current. I'll be happy to share my measurements with you. 
> 
> There is no coax anywhere in my antenna system. So my solution was to put a choke with high impedance to common-mode current right at the output of my antenna tuner. I encourage users of open-wire line to do that.
> 
> Al  W6LX
> 
>>>> In all cases of a radiator fed with coax, 
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