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Tuner Thread

Subject: Tuner Thread
From: John Brosnahan <broz@csn.net> (John Brosnahan)
>My own opinion is the best QRO tuner is an old Johnson KW box. Too bad
>there's nothing like that around any more, but that would be a $3000  tuner
>now!

Tom, I have to disagree with you on this one.  I had three of the Johnson KW 
Matchboxes and all performed with the same limitations.

1)  They can't handle 1500 watts on 10 and 15 meters (and this was to a nominal
50 ohm load).  Late in a contest with high duty cycle CQing to a nominal
Yagi they 
will unsolder their bandswitch connections.  (Why a tuner with a Yagi?  When
operating with multiple antennas and switching between them or combining them
it is very handy to have all of them look like a precise 50 ohm load so any
one or combination of any presents the same load to the amplifier, so the amp
 is not over or under loaded in some conditions.)

2)  Tuning range on 80 meters is minimal.  Cut a dipole for 3.775 MHz and the
tuner may or may not match it at 3.5 MHz--depending on the feedline
length.  Indicating that its range of reactance "removal" is pretty limited.

3)  No 160 meter coverage.

On the plus side: they do make excellent preselector filters in a multi/multi
situation, and for loads that they can match on 40 and 20 meters they do
quite well.

One ham's opinion!  73  John  W0UN

(Did I mention that the VSWR meter is a V (as in voltage) meter that needs to
be reset for each band, not a forward/reflected power meter?   Just a minor
inconvenience but it means one more knob to diddle when changing
bands.)


John Brosnahan  
La Salle Research Corp      24115 WCR 40     La Salle, CO 80645  USA
voice 970-284-6602            fax 970-284-0979           email broz@csn.net


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