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[TowerTalk] 10 m / 15 m interaction?

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Subject: [TowerTalk] 10 m / 15 m interaction?
From: sbookout@mail1.mnsinc.com (Steve Bookout)
Date: Thu, 16 Oct 1997 10:17:21 -0400
Hi guys,

Looking for the voice of wisdom and practical experience here.

Last weekend I put up my 5/5 stack on 15 at 40/80 feet, with a 105
Hygain 8 feet above the top antenna.

I had gotten the info off the Hygain homepage on modifying the antenna
for optimum CW performance.

At 2 electrical half waves of coax the 10 meter SWR is no better than
1.8:1.  

We pulled it all down and on 4 foot saw horses the SWR is fine, although
the curve is a bit low (to be expected on the gnd).  I hung the antenna
by the gin pole rope vertically on the side of the tower with the
reflector about 8-10 feet off gnd.  SWR is fine.  1:1 at 28.025 or so. 
Nice and broad, but not flat, which would cause suspicions.

Any hints?

My concerns are that my 15 is on a 36 foot boom, close to a 10 meter
full wave.  But, the boom would be at right angles to the 10 meter
elements, kinda like a 40 meter rotated 90 degrees.

I'm 99% sure it interaction, not some mechanical problem.  

If it is the boom lenght of the 15, I could extend some alum tubing out
one end or both ends to make it 40 or so feet. 

I would like some advice from those in the know.  These antennas are to
large to be putting up/down multiple times, because of my errant
speculation.  Besides it wears out the help.

After several tiring hours, we were back at square one, with a tower
with no antennas on it! (had to bring the 15's back down to add an inch
and half to get them down where they belong; 21025).

Any thought would be appreciated.

73 de Steve, NJ4F


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