k3bu@optimum.net wrote:
>> Hi TB'ers!
>>
>> Anyone out there with experiences on wideband transformers wich
>> can handle some power?
>> I've been trying to match 20 ohms to 50 ohms for a mobile whip,
>> but no success so far...
My MonstIR Yagi has a 50 ohm to 22 ohm balun that is good from
7 MHz to 54 MHz (I measured it on a network analyzer). In your
case, you only need an "un-un" not a "bal-un". Even easier.
You can simply get a big 43 matl toroid and wind an autotransformer
on it. Make a tri-filar winding and connect the three wires
in series (end of first wire to beginning of second wire, etc).
Then connect the high impedance side across the 3 wires in
series and connect the low impedance side across just 2 of
the wires. Use fairly large wire (14 to 18 gauge) with thin
insulation, to minimize leakage inductance.
Rick N6RK
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