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[TowerTalk] Force 12 C4SXL - Intermittent SWR

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Subject: [TowerTalk] Force 12 C4SXL - Intermittent SWR
From: (Albert C. Burnham)
Date: Sat, 20 Jun 1998 20:16:25 -0700
I am having a peculiar problem with the C4SXL:

When not using my amp, there is an intermittent SWR jump from resonance
(around 1.3:1) to around 2.5:1.  This may or may not be affected by wind;
I'm not positive.  But this problem occurs on all bands covered by the
beam, including 40 meters. (Actually, the SWR jump is more pronounced on
40 meters; when the SWR is high, it is around 5:1 or 6:1).

<bold><italic><underline>But when the amp is turned on, the SWR falls to


One possibility is bad coax or connectors, I suppose; however, there are
TWO separate runs of coax to the beam, one for 40 meters, and one for the
other bands.  And, as previously mentioned, this problem occurs on all
bands covered by the beam.

I also use a wire antenna, and the problem does not occur on it.  The
wire antenna is wired through the same circuitry as the beam, ie, coax
switch, amp, low pass filter, SWR bridge, tuner, etc. -- this would seem
to eliminate internal shack wiring as the cause.

There is a Force 12 balun for 40 meters, and one for the other bands.  I 
doubt that there could be two bad baluns.  Also, if a balun were bad,
putting more power to it would probably make the problem worse, rather
than better.

One obvious solution is to always run the amp.

But I would like to eliminate the problem.

Any constructive comments/suggestions will be greatly appreciated.

With thanks and 73,



                         (@ @)


                   Albert C. Burnham, K6RIM

                   409 Summit Drive

                   Corte Madera, CA 94925


                   Phone:       (415) 924-6783

                   FAX:         (415) 924-6678




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