[Elecraft] Balun for KAT2

[Bill Coleman]

On 1/13/02 6:08 PM, Steve Lawrence at Steve.Lawrence@ITWFEG.COM wrote:

>While I didn't conduct testing to measure losses, I reasoned that a simple
>W2DU choke type balun would have lower loss over a transformer type balun
>wound over a toroid. 

Just because it is wound over a toroid doesn't mean it isn't as efficient.

Guanella or W1JR baluns are electrically identical to W2DU baluns, and 
can be just as efficient if properly designed.

>After reading W2DU's book "Reflections" I've really changed my view on
>SWR.  Mr. Maxwell clearly demonstrates that SWR alone is not a reliable
>indication of good antenna match (or performance).  In fact, a low SWR may
>really mean high losses, low efficiency and other undesirable conditions!
>So, I've begun to look toward improving efficiency -- not minimizing SWR.

It's all about loss, not SWR. (Although a low SWR can often reduce 
feedline losses)

>Why?  Well briefly, a 50 ohm dummy load will indicate a 1:1 SWR, yet
>radiate poorly!  All power entering the transmission line is radiated,
>independent of SWR -- less losses (in coax, ground, etc.).  As such, I've
>looked at elements in my antenna system that are low loss.  The W2DU type
>choke balun is in this class.

Coiled-coax type choke baluns are probably the lowest loss of the bunch. 
They are cheap, but their frequency range is somewhat restricted, and 
they can be bulky and heavy.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901