On 5/31/2020 7:22 PM, Peter Dougherty wrote:
This is a brand-new balun from InnovAntennas, made specifically for this
antenna, received this past Thursday.
The word "balun" has been used to describe nearly a dozen VERY different
physical things, and is thus totally useless as a descriptor of what you
used (or what they sold you). Buy me a case of a good single malt Scotch
and I'll run down the list.
I have extensively studied only one set of those "things," common mode
chokes formed by winding a length of transmission line onto a ferrite
core that is lossy at the frequency(ies) of interest, forming a parallel
resonance in the common mode circuit where the RESISTIVE component of
the low-Q parallel resonance is what makes the choke work.
A good common mode choke does not interact with a well-designed antenna
unless the Zo of the transmission line wound onto the ferrite core is
mismatched to the antenna. And I emphatically do NOT call them "baluns"
because use of that word obscures understanding of HOW they work.
73, Jim K9YC
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