On 12/15/2025 4:44 PM, BOB WATWOSQQ wrote:
If I want to broaden the operating frequency of a common mode choke, can
you stack two different mixes, say a 31 and a 43 to create one common choke?
My many years of research yielded a Cookbook that includes a table of
designs that use multiple chokes in series all on Fair-Rite #31 cores,
to provide wider choking bandwidth and greater power handling.
I do NOT find #43 or other NiZn cores useful on HF because of their
higher Q and the wide manufacturing tolerances associated with all
ferrite products.
My designs are for use in coaxial or 2-wire transmission lines made with
insulated wire touching each other, feeding antennas that are reasonably
well matched the the line. The Zo of that 2-wire line is close to 100
ohms. The chokes are most effective at the feedpoint.
While they can be used at the feedpoint of antennas that are NOT
resonant at operating frequencies, their power handing capability is FAR
lower. Power handling is even worse for off-center fed antennas.
The Choke Cookbook is http://k9yc.com/2018Cookbook.pdf
The tutorial is http://k9yc.com/RFI-Ham.pdf
My website is k9yc.com/publish.htm
73, Jim K9YC
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