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[Towertalk] Force 12 XR-5 SWR problem (?)

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Subject: [Towertalk] Force 12 XR-5 SWR problem (?)
From: (Dave Dunbar, N0RQ)
Date: Thu, 19 Sep 2002 08:48:01 -0500
I have a Force 12 XR-5  (5 band, 10 element "multi-monobander") laying =
on the ground, almost ready to up right after the Trylon 64' goes up =
this Saturday.  However, I'm having an SWR issue that perhaps someone =
has some ideas on.

The SWR across all 5 bands except 15m is either good or quite =
acceptable.  But on 15m, it doesn't look so good.  I checked it while it =
was mounted it at 9' on a sturdy tetherball pole, as well as when it was =
pointing straight up in the sky (the 15m driver would have been about =
12' in the air).  I've checked it using several different types and =
lengths of coax, and I've tried an alternate balun (both Force 12).  =
I've tested with both a rig (FT-900) and an MFJ 259B antenna analyzer.  =
And of course I've double- and triple-checked the assembly, element =
lengths, etc.  It was done according to the Force 12 instructions, which =
were very good.

On 15m, the best SWR is near 21.6, with an SWR of about 1.5:1.  I can =
lower the "resonant" frequency to around 21.3 to 21.4 by lengthening the =
15m driver, but the best SWR I can then get is still almost 2.0.  Nicht =
gut. =20

Is there something I'm missing?  Is the thing simply too close to the =
earth to give me a reliable reading?  Do I put it up on the tower with =
the suggested 15m driver length, or should I stretch it a few inches and =
hope for the best?  (This is my first HF beam and first real tower, so =
I'm kinda nervous about it.)  Comments appreciated!

73, Dave, N0RQ

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