what a 1:1 choke balum used for
John Popelish wrote:
Roy Lewallen wrote:
Broadband transformers, which can operate well over several decades of
frequency, commonly use ferrite cores which are essentially resistive
over most of the operating frequency range. The sign of the impedance
is unimportant to the transformer's operation; all that's necessary is
that its magnitude be adequately high over the operating range (and of
course that the core's permeability be adequately high). The wide band
high impedance requirement is virtually impossible to meet with an
inductive core whose impedance is approximately proportional to
frequency, but easily done with cores whose impedance is essentially
resistive.
As long as the impedance is high enough, what is the need for it to be
constant (or even nearly so) over a useful frequency range?
None.
Roy Lewallen, W7EL
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