So you move the loading coil from the base of the antenna to inside the tuner
in the radio (with some coax in between). How does that affect the radiation
efficiency/?
On Thursday, July 3, 2025 at 01:57:33 PM MST, Jim Brown
<jim@audiosystemsgroup.com> wrote:
> https://www.dxengineering.com/parts/cha-ss25
That looks like a great solution, Dave! I strongly suggest against a
loading coil for 40M, using a tuner built into the radio instead, with
or without some top loading. Loss in short lengths of decent-size coax
on 40M is pretty low, even with significant mismatch. An excellent study
in QEX about ten years ago showed that inductive loading at the base
greatly reduces the radiation efficiency, because it's at the current
maxima! The study included the construction of multiple configurations
of loading, and very rigorous measurements.
73, Jim K9YC
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