[Elecraft] Slightly Unbalanced dipole?

[Bob McGraw K4TAX]

Al:

Al et al;

I do agree.   And in fact my 250 ft center fed antenna  with 75 ft of 
window feedline terminates at the operating position into a Balun 
Designs 1171T. Then a coax jumper of about 2 ft long, which is actually 
a model 8232 from The Wireman, Common Mode Choke between the balun and 
the output of the KAT500 tuner.

I was asked recently on another discussion group why I used both a balun 
and a common mode choke.  The balun itself does not provide adequate 
common mode choking ability for all bands 160M - 10M.  Since I must use 
a coax jumper between the balun and tuner, why not just make it a common 
mode choke.    All seems reasonable and simple...... like me.  Thus one 
cable and 2 connectors and a quantity of ferrite beads does double duty.

And yes for my coax center fed antennas I use a 1:1 current balun, which 
is no  more than a length of coax with a number of ferrite beads at the 
feed point in a PVC enclosure that serves as the center insulator.   I 
forget the brands and models.   They have been up on the tower for 
several years.

73

Bob, K4TAX


On 1/13/2019 5:42 PM, Al Lorona wrote:
> By the way, whenever Jim says, "...a very good common mode choke at the feedpoint of an antenna...," he means an antenna fed with coax. For the rest of us, of course, that choke would (should) go at the output of the antenna tuner, whether in the shack or close by.
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> Al  W6LX
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>