[Elecraft] Balanced solution for KAT500 tuner?

[Jim Brown]

On 9/29/2012 9:12 PM, Robert G. Strickland wrote:
> What I'm curious about is whether some such device, at the feed point of a doublet,
> in turn fed by window line is of any use [assuming an appropriate tuner at the radio
> end of the line]. You have said, accurately so, that a current choke at the feed
> point of a dipole [let's leave off-center fed antennas out of it at this point], in
> turn fed by coax,

In all of this discussion, I have not used the word "coax."  You have 
read that somewhere else.

> keeps RF from flowing on the outside of the coax and subsequently
> becoming "part of the antenna" and in turn picking up noise/etc. Another way of
> phrasing my question is, does the coax situation apply to open feeders, also?

YES!  That is EXACTLY what I have repeated, over and over again.  It has 
NOTHING to do with coax.  Coax, if it is not decoupled by a common mode 
choke, simply ADDS to the imbalance that is already present.  EVERY 
transmission line needs a common mode choe at the feedpoint to decouple 
the line.

Off-center fed antennas, like the so-called "Windom" in all of its 
variations, are WILDLY unbalanced. As a result, they are notorious for 
being NOISY, for putting RF in the shack, and for toasting common mode 
chokes.  It is a complete fiction to feed with with parallel wire line 
and CALL it balanced, and decide that it needs a balanced tuner! The 
antenna is unbalanced, so the feedline is unbalanced, and a balanced 
tuner does nothing except transfer dollars between the purchaser and the 
seller.

In the old days, when RFI did not exist (few of us are old enough not to 
remember TVI in the 50s), the Windom MIGHT have been a good idea.  
Today, with RF noise sources everywhere and home stereo rigs full of Pin 
One Problems ready to  bring RF into equipment and detect it, Windom 
antennas are a really bad idea.

73, Jim Brown K9YC