[AMRadio] Johnson Match Antenna tuner


fkamp at comcast.net fkamp at comcast.net
Sat Aug 7 13:47:18 EDT 2004



Rivpapa1 at aol.com wrote:
> 
> What is the proper adjusting procedure for using a Johnson Matchbox ant
> tuner..There are two controls..tuning and Matching...Which is adjusted first?  tnx

That is a darn good question.  Unfortunately there are no darn good
answers.  It depends on the antenna and what is being matched.

I use a Johnson Matchbox.  I find that I need to twiddle both knobs
while watching the SWR indicator to get a decent match. 

The knob on the left of my matchbox varies the coupling.  The knob on
the right does the actual tuning.

I start by setting the knob on the left to its far left position, then
swing the knob on the right until I see a change in reflected power.  If
I don't see much of a change, I move the knob on the left a little and
swing the right knob again.  It helps to have the band switch in the
proper place.

Once you see the reflected power drop, turn both knobs simultaneously
for a more significant drop.  Do all this at the lowest possible power
level. A level that will give an adequate meter indication.

That is the way I do it.  Sort of a 'twist all the knobs possible' until
you see a drop in reflected power.  If you never get to the point where
there is a drop in reflected power, your antenna impedance may not be of
a value that the box can match.

Regards,
Frank Kamp



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