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Hi all,
I want to make a small transmatch (RX, TX up to 10
Watts, or so) to tune LW 41 m (or smaller T-ant) in the range 50 ... 550
kHz.
I am not too good in theory... but I believe that
the most efficient system is the popular loading coil (home made
variometer, and taps to find 50 Ohms match).
The simple variometer (cylindrical coil in another
cylindrical coil) is easy to make and works fine on 136kHz. However, it is
possible to change inductance in the range about 1:2 or 1:3 only, not much
better. Therefore the redudant inductance is too high to fetch the ant to
resonance on 550 kHz.
Solution would be to make a more sophisticated
variometer (best: sphere in sphere) to reach the ratio 1:10 or so.
Or, to use a different kind of network. Pi network,
L network or T network. BTW I would also prefer to use a rotary switch and
solder twenty condensers rather than to make twenty taps on a coil
wound with litz wire...
How did you solve this yourself?
Thanks, 73, Petr, OK1FIG
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