Message-ID: <20120310092700.dk7nljhbi88sskos@webmail.senselan.ch>
Date: Sat, 10 Mar 2012 09:27:00 +0100
From: traumwandler@sensemail.ch
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Subject: LF: A Matchbox for 136 kHz
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My 1KW TX is a derivative from G3YXM?s Mk 1. It is very SWR sensitive and when
the transistors begin to sing, the end is near ;-)
But the variometer is out in corner of the garden and my shack up under the roof
of this huge 220 year old farmhouse. I was tired to retune the variometer all
the time with weather changes and QSY. So I built an antenna tuner for my shack
with old components from the junk box.
Nothing special, just an L-Tuner with the L in series. The inductor is a roller
coaster with 25 uH and additional coils I can short out. Tuning range goes from
0 to 125uH. The capacitor is a variable 1000pF, plus 5 huge brown mica
condensers I can add with 5 switches: 1/2/4/8/16nF giving me a total capacity
of 32nF.
Now I can adjust the SWR always for a 1:1 and the transistors stay happy. Most
of the time I?m using about half of the max values and the components don?t
get warm with a Kilowatt.
Snow or rain, dry weather or a QSY of some 100 Hz: I stay in the shack without
worrying about exploding transistors. A very useful tool. Also for our future
MF band.
73 de Toni, HB9ASB

PS. Stefan: thanks for the schematics of your TX