The potential for common mode currents on feedlines,
whether they be phased verticals or stacked yagis, or
simply antennas within a few wavelengths of each other
which attach to a common switch....is great.
You absolutely MUST make provision for an RF choke,
or line isolator, or clip-on ferrites, to assure that
the antennas remain isolated. Otherwise, you'll see
your patterns destroyed.
This is a much greater problem than commonly realized.
You also have to remove the RF current from control and
power lines going to the tower base. Everything has
potential to conduct current, and destroy antenna isolation
as a result.
Even the Ameritron switch manuals advise this. Stackmatch
should, as well. (haven't read the manual, Jay...maybe you
say that already.)
Jim/n2ea
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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