[TowerTalk] common mode chokes, baluns and multiband, doublets

Jim Brown jim at audiosystemsgroup.com
Tue Dec 12 13:12:49 EST 2017

Hi Ward,

The problem is that all of these "things" work better or worse than 
others, are more or less frequency-sensitive than others, and have 
unintended consequences.

For example, the coil of coax and quarter wave sleeve are VERY frequency 
sensitive and the coil of coax is quite sensitive to the length of the 
transmission line. Coax through ferrite beads depends STRONGLY on which 
beads are used, and the operating frequency.

73, Jim K9YC

On 12/12/2017 9:19 AM, Ward Silver wrote:
> For example, here's a list of "things" that are all considered to be 
> "baluns":
> - coil of coax
> - coax wound on ferrite cores
> - coax through ferrite beads
> - quarter-wave sleeve
> - Guanella transmission-line structure (a.k.a. "current balun")
> - Ruthroff transmission-line structure (a.k.a. "voltage balun")
> - half-wave transmission-line structure
> - etc
> Some of the "things" also implement impedance transformation, but 
> impedance transformers don't necessarily perform the balun "function," 
> adding to the general confusion. 

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