On 1/2/2012 2:35 AM, Steve Hunt wrote:
> It only requires the realisation that the outer surface of the coax
> braid can - and does - act as an "unintentional" antenna wire to see the
> wisdom of using a choke.
I like the way you phrase your response with those questions. I also
emphasize those concepts, but using different words.
But it's also critical to convey the concept that a parallel wire line
can carry considerable common mode current, thus doing exactly the same
thing, if the antenna is unbalanced. The words "balanced line" are
misleading, because current on the line won't be balanced if connected
to an unbalanced antenna or unbalanced rig. That's why I am careful to
talk about parallel wire lines, not balanced lines, and it's why common
mode chokes are just as necessary with parallel wire lines as with
coax. The only difference is that with coax, the need is more obvious
and easier to explain.
73, Jim K9YC.
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