[TowerTalk] BALUN revisited again

[TexasRF at aol.com]

Great answer but applies to a different question. Perhaps to the original  
posting that you deleted?
 
73,
Gerald K5GW
 
 
 
In a message dated 4/7/2016 11:47:50 A.M. Central Daylight Time,  
jim at audiosystemsgroup.com writes:

On  Thu,4/7/2016 8:28 AM, TexasRF--- via TowerTalk wrote:
> Why would you  not just solder the balun flying leads to a PL259  
connector
> for  connection to the dipole connector and be done with it?

First, the word  "balun" is used to describe almost a dozen very 
different things that I  can think of. It's a contraction of "balanced to 
unbalanced," implying a  conversion.

Second, it is ALWAYS good practice to use a ferrite COMMON  MODE CHOKE at 
the feedpoint of ANY antenna that does not intentionally USE  the 
feedline as part of the antenna. The reason is to PREVENT the feedline  
from being part of the antenna, which in turn prevents the feedline from  
picking up signals and coupling them to the antenna. Those signals  
picked up on the antenna may be noise, or from some direction other than  
that favored by the antenna.

Third, the best common mode choke for  the HF bands is one formed by 
winding multiple turns of the feedline  through one or more ferrite 
cores. Simply clamping a lot of cores onto the  coax WILL NOT WORK WELL. 
Neither will a simple coil of coax. See the  references below to 
understand why.

I first did research common  mode chokes in 2004-5, and published the 
results as a technical paper for  the Audio Engineering Society. The 
emphasis there was preventing RFI to  audio systems. After moving to W6 
in 2006, I continued my research and  published the first version of 
http://k9yc.com/RFI-Ham.pdf in 2007. There  have been well over a million 
downloads, and some key elements of the  material has been added to the 
ARRL Handbook. Slides from a talk I've done  for several hamfests and 
clubs are at  http://k9yc.com/CoaxChokesPPT.pdf

73, Jim  K9YC
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