[CQ-Contest] Stack Matching/WX0B Stackmatch

Chad Kurszewski WE9V kurscj at oampc12.csg.mot.com
Tue Jun 10 11:52:06 EDT 1997

With the fall of W9JA's (ex-KS9K) 15M tower, rebuild is in process.

I also am planning on rebuilding the stack match box, but am wondering
about the purchase of a WX0B Stackmatch.

My present design always uses at least one quarter-wavelength line to
assure a constant feedline length regardless of what antenna/combination
is selected.  (This "ensures" operation in the same part of the Smith
Chart, thereby not requiring amplifier re-tuning for different antenna
selections.  If the quarter-wavelength line is switched out, you would
be operating in the opposite part of the Smith Chart.)

I have a few questions for the owners of WX0B Stackmatches:

1)  Other than the fact that the transformer doesn't do a perfect match
    for the stack combinations, has anyone noticed amplifier mis-matches
    when switching to a single antenna?  (Or is that the beauty of a
    transmission line transformer?)

2)  Has the shifted SWR curves caused anyone any problems?

        For example:
        Ant.Impedance (ohms)              25              100
        Single Ant SWR                  2.00:1          2.00:1
        2-stack WX0B SWR                1.77:1          2.25:1
        3-stack WX0B SWR                2.67:1          1.50:1

3)  Any reliability issues?

4)  Anything else I should know?


Chad Kurszewski, WE9V         e-mail:  Chad_Kurszewski at csg.mot.com
The Official "Sultans of Shwing" Web Site:  http://www.QTH.com/sos

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