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

[Chuck Gooden]

A coil of wire is an inductor with an air core and the principle of of a 
inductor will still apply.  However an air core inductor will not be as 
efficient as an inductor with a core depending on the mu of the material 
used.

Chuck - K9LC



On 12/12/2017 11:52 AM, David Robbins wrote:
> Why must a balun provide isolation?  how can a coil of coax be considered a balun as there is no isolation of the currents on the inside of the coax provided like there can be with a transformer.
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Ward Silver
> Sent: Tuesday, December 12, 2017 17:19
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] common mode chokes, baluns and multiband, doublets
>
>   >  "Balun", def: the most misused and misunderstood word in all of ham radio.
>
> My approach, when discussing baluns, is to present the "balun" as a "function," not necessarily a "thing."
>
> The balun "function" is to transfer power between balanced and unbalanced systems while at the same time providing isolation between them.
>
> Any "thing" that implements the function can be considered a "balun." There are lots of "things" that implement the "function."
>
> 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.
>
> 73, Ward N0AX
>
>
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