|[AMRadio] WTB - MURCH UT-2000A|
w9ac at arrl.net
Sat Jun 12 16:33:35 EDT 2010
> then re-wire it.
I sure would. To a reversible "L" for use with coax lines -- or a balanced
version of the L for open lines.
With the classic C-L-C "T" design, multiple panel control settings can
create an illusion of a low-loss transformation (unless output C is always
maximized for the given load). The T is capable of reasonably low loss when
the L and C components have a Q > 200 and the output C has > 3000-5000 pF of
maximum capacitance where the connection point to the line is under 25-ohms.
Myself, I cannot imagine using common wire antennas where the feedline Z at
any point on the transmission line is less than 50-ohms. That almost always
indicates an electrically short and inefficient antenna unless extraordinary
measures are taken at the tuner and antenna to minimize system loss. Most
off-the-shelf T tuners suffer great losses with low operating Z. Unless its
for mobile use, I really do not want to use antennas that are much less than
a physical 1/2-wave at the lowest operating frequency.
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