[Elecraft] Balanced solution for KAT500 tuner?

[ab2tc]

Hi,

So are you suggesting using a choke balun on both ends of the parallel wire
feedline?

AB2TC - Knut


Jim Brown-10 wrote
> On 9/29/2012 5:40 AM, Barry, Stephen wrote:
>> Does Elecraft have a balun solution for balanced feeders for the KAT500
>> at 500 watts?
> 
> See the Choke Cookbook that is Chapter 8 in my RFI Tutorial, and the 
> discussion in the preceding pages, for an excellent common mode choke 
> that will satisfy this need.  Use one of the chokes that is bifilar 
> wound with #12 THHN, connected as a parallel wire transmission line 
> between your parallel wire line and the tuner.
> 
> http://audiosystemsgroup.com/RFI-Ham.pdf
> 
> BTW -- the words "balanced feeders" and "balanced feedline" are pure 
> fiction. You will note that I used the words "parallel wire" to describe 
> the feedline.
> 
> The balance of any system, including an antenna system, is defined equal 
> impedances to the reference plane. For antenna systems not on aircraft, 
> that reference plane is the earth, and the transmission line is only 
> part of that system. Most wire antennas that hams are able to erect are 
> unbalanced by their surroundings, which in turn causes the feedline to 
> be unbalanced. Imbalance in an antenna is caused by off-center feed, 
> ground slope, sloping wires, trees, buildings, even the varying ground 
> conductivity around the antenna.
> 
> This imbalance will cause current on the feedline to become unbalanced, 
> which makes it part of the antenna. The feedline picks up noise and 
> couples it to the antenna (because it's part of the antenna).
> 
> For this reason alone, smart hams have learned to use a common mode 
> choke at the feedpoint of an antenna  This decouples the feedline from 
> the antenna, preventing noise pickup (and keeping RF out of the shack).
> 
> 73, Jim K9YC
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