[Elecraft] Balun suggestions

[Don Wilhelm]

Wes,

I don't mean to be contentious, but under ideal conditions, what Ron 
said is true.  Even though we often refer to the output of the KAT500 
(or any other device that normally connects to a coaxial line, the 
currents on the output should be equal and opposite - which is the 
definition of balanced.
Consider the currents between the center conductor and the inside of the 
shield for coax.  They must be equal and opposite.  It is the common 
mode current on the outside of the feedline that produces any unbalance.

So connecting a balanced feedline to a PL-259 is not so far fetched - 
providing the shell of the PL-259 (and enclosure of the KAT500) is not 
grounded.  If you have decided to ground your KAT500, then you would 
need to use a balun - so "it all depends".  Be aware of "sneak grounds".

73,
Don W3FPR

On 2/4/2016 7:17 PM, Wes (N7WS) wrote:
> I just pinched myself; I'm not dreaming and it's not April 1st, so I 
> guess you're serious.
>
> You are also so wrong on so many points, I'm not going to waste time 
> trying to refute or correct them.
>
> Jim, please ignore everything said below.
>
> Wes  N7WS
>
>
>
> On 2/4/2016 3:05 PM, Ron D'Eau Claire wrote:
>> Your feed line will do the job by itself so no additional "balun" is 
>> needed.
>> Keep in mind that a 1:1 balun is really just a length of feed line, 
>> usually
>> wound on a toroidal core to make the required length shorter than if 
>> it was
>> in open air. The "old-school" baluns were just a pair of air wound 
>> coils.
>>
>> If your balanced feed line is at least 1/4 wavelength long, the currents
>> will be "balanced" (equal and out of phase) at the antenna. That assumes
>> your antenna is perfectly balanced to provide a perfectly balanced load,
>> which "balanced" antennas almost never do. There are just too many
>> variables. So expect excellent results even with shorter feed lines. The
>> amount of radiation (or pickup) from the feed line even at the rig 
>> end is
>> small in any case.
>>
>> Connect one side of the open wire feed line to the KAT100 SO-239 
>> center pin
>> and the other to the KAT100 ground terminal.
>>
>> 73, Ron AC7AC
>>
>>
>>
>> -----Original Message-----
>> K2/100 and KAT100 here.
>>
>> I am changing around my modest antenna configuration now.  I have 
>> been using
>> the K2/100 with my AH-4, and now wish to use the KAT100 with balanced
>> feedline antennas.
>>
>> What balun, homebrew or commercial, if any, should I use?  I almost 
>> always
>> run 5 watts, all CW.
>>
>> 73 de W6OGC Jim Allen
>>
>>
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>
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