[Elecraft] Balanced tuners

[Vic Rosenthal]

David Honey wrote:

> A true balanced tuner has the balun at the input where, once the ATU is 
> propery adjusted, will always be at 1:1 and hence no reactive elements. 

This is not correct.  As you suggest, placing the balun at the input of an 
unbalanced tuner is an attempt to solve the problem posed by operating a balun 
in the output of the tuner, where the impedance is uncontrolled.  However, W7EL 
(I can't find the reference just now) has shown that this method is actually no 
better than the balun in the output!

A true balanced tuner does not have a balun at all.  For example, the Johnson 
matchboxes make the unbalanced to balanced transition by using an unbalanced 
link coupled to a symmetrical parallel-tuned tank circuit that is connected to 
the feedline.  There are several true balanced tuners available: MFJ makes one, 
and I've seen others.  Just Google 'balanced tuner'.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco