[Amps] Baluns / UNUNs in QRO

Tomm Aldridge KD7QAE at ARRL.NET
Fri Jan 21 14:09:01 EST 2005


Rather than put an antenna tuner in series with my amp, why not add a 
wide band RF impedance transformer to the output of the amp and go 
directly to the feedline?  Seems that adding the plate tuner in series 
with the antenna tuner is just compounding losses.  For example, I run 
450 ohm ladder line to my (non-resonant) antenna.  It is now fed by a 
balanced-balanced tuner (2 26uH motorized rollers and 2 500pF variables 
that can be moved from input to output as Z determines) that is fed by 
my solid state 50 ohm out rig.  It seems to me that I could just design 
the plate tuning circuit to match 4k to 450 and add a 1:1 current mode 
BALUN to the output of that and be done rather than going from 4k to 50 
to BALUN to 450 as would be the case with the current 50 ohm output designs.

Am I missing something here?



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