On Mon, 01 Jun 2009 14:14:53 -0400, Bill Tippett wrote:
> I *believe* the DXE style physically breaks the flow of common
>mode current through the shield by using isolated transformer
>windings through a 1:1 binocular core transformer.
A real transformer certainly does break that current path. BUT --
any asymmetry between the windings, as well as any stray
capacitive coupling between the windings, provides a path between
windings for common mode current.
The highest quality audio transformers (for example, www.jensen-
transformers.com) are wound with a foil barrier between windings
that functions as a Faraday shield when properly wired to external
circuitry.
>It would be interesting if someone could define "extremely high
>isolation impedance". :-)
I've done my part by publishing graphs of measured data and
documenting exactly how measurements were made. :)
BTW -- I object to use of the word "balun" to describe what is
really a two-winding transformer (for example, in Carlos's
otherwise excellent description of his RX antenna). Likewise, I
object to use of the word "balun" to describe what is really a
common mode choke. Using the wrong word leads to confusion and
muddy thinking.
73,
Jim K9YC
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