Yes Jim,
But if we draw the Venn diagram of RF Chokes and BALUN's I speculate there is
something in the overlap, is there not?
Jon
On Oct 31, 2013, at 6:42 PM, Jim Brown wrote:
> On 10/31/2013 2:39 PM, Rick - DJ0IP / NJ0IP wrote:
>> A BALUN and an RF Choke are synonymous. They are the exact same thing
>> (except for the connection terminals).
>
> This is TOTALLY WRONG!
>
> I know of nearly a dozen VERY different things that are described by the word
> "balun."
>
> An RF choke is an inductor, and it some frequency it will resonate with its
> own stray C.
>
> A coil of coax is an inductive common mode choke -- the fact that it is
> inductive makes it a LOUSY common mode choke. It is often called a balun.
>
> A coil of coax wound through lossy ferrite cores is a RESISTIVE common mode
> choke -- resistive because the ferrite core is lossy, because it resonates
> with its own stray C, and the choke has been wound to place the resonance in
> the range of frequencies where we need a choke.
>
> A bunch of ferrite beads on a piece of coax is a common mode choke. Most such
> "string of beads" chokes are inductive, which makes them lousy common mode
> chokes. The original W2DU common mode choke that he called a current balun
> used 100 or more #73 ferrite beads, which are made only in a size that fits
> small diameter coax (RG58), and which DO have the desired low Q (very lossy)
> resonance in the HF bands. These original W2DU chokes are GOOD common mode
> chokes.
>
> A half wave of coax has used as part of the feed of monoband antennas, and
> that is called a balun.
>
> There are arrays of common mode chokes (series/parallel) that used to
> transform impedance and are called baluns.
>
> There are multi-turn transformers that are called baluns.
>
> There are active electronic products that drive video onto CAT5 cable that
> are called baluns.
>
> All of these are VERY different from each other. None of them are an RF Choke.
>
> 73, Jim K9YC
>
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