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[TowerTalk] X9

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Subject: [TowerTalk] X9
From: (Jon Barclay N5JA)
Date: Wed, 19 Nov 1997 21:25:40 -0600
Gary Myers wrote:
> To the "experts" on stacking tribanders :
> Is there a problem/concern with stacking a X9 over an X7? An equivalent
> might be to stack a TH7 over a TH6? This would allow a X9 to be at the
> top with the 2 el 40 add on and 1 or 2 more X7s below it.

I'm not an expert and haven't stacked tribanders, but I have made sure
that when I point two antennas in some desired (designed) direction that
the signals are in phase in order to get some benefit from them.  This
has been to much benefit the last couple of year on 10M using a 4-ele.
on one tower and a 5-ele. on another, and I've heard a number of signals
on the pair that I couldn't hear on either.  Also, by fortune alone,
when the pair is in phase pointed NE it cancels my power line noise from
the SW.

Anyway, all you need is a friend a half-mile or a mile away to provide
you with a reference signal, a couple of dummy loads (or even 50-ohm
resistors, since you'll just be terminating the feedlines from the
antennas), and access to a half-decent dual-trace oscilloscope.  I
terminate the feedlines with the resistors/dummies, and use my old
Tektronix 454 'scope (sub-$300 used) to look at the signals at the dummy
loads (via probes to a tee-connector), while my half-mile-distant friend
transmits a reference signal.  I can easily see the signals from both
antennas and compare the phase of the two.  Then, just adjust the length
of one of the coax cables to get the signals in phase.

I'm currently joining these inside the shack with a WX0B StackMatch to
give me #1/Both/#2 capabilities, and could easily add a half-wave line to
the third port on the StackMatch to enable me to deliberately use the
antennas out-of-phase (see WX0B's notes for BIP/BOP operation at:
for details).

This provides a good sanity check for phasing even like tribanders just
in case the factory swapped the wires on you in manufacturing one of
your baluns.

>From my experience I expect you'd still get the benefit from stacking
the unlike tribanders provided phasing between them was correct.


Jon A. Barclay  N5JA  (ex-AA5BL)

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