Topband: 160 Antenna Struggles

[Charles W. Shaw]

Rip,
         Just to add a bit to the good advice which Herb has already offered:

MECHANICALLY --
         You have 49 feet vertically made from beam parts, and I 
imagine you also have guys to hold it.  Try this:  for a top set of 3 
guys, use about 30 feet of wire each, well connected electrically to 
the vertical with a light weight end insulator on each, then continue 
the guys as far out as possible with rope.  (Dacron about 3/16" 
weathers best and doesn't change length with moisture enough to 
notice.)  Now you have a vertical with a three-pronged top hat.
         If it is possible to adjust the three wire lengths 
conveniently, plan on doing that to put resonance where you want 
it--otherwise use a variable capacitor in series between the coax 
center and the base of the vertical.  (A receiving-type close spaced 
tuning capacitor from an old tube radio will work well with your 100 
watts out.  You can mount it in a plastic box for protection from 
rain and bugs.)
         I very successfully use 4 elevated radials sloping up at a 
45 degree angle.  BUT, they are 20 feet above ground, and I also have 
much more height in the vertical than is available to you.  If 
possible, try several non-resonant (shorter) surface radials (more is 
better) until you get things going.  You may later want to bury 
them.  The idea is to get going, then refine things.  I've never 
built an antenna that was finished--they are always a work in progress.
         With your elevated radials that slope upward, you have 
probably already found that more length is required than a "formula" 
indicates.  As a rough guide, you may need to add a length similar to 
their height above ground--assuming that the vertical radiator is 
already adjusted for a frequency which suits you.
         Have fun.  Antennas are not just "accessories" to the fun of Topband.

73, Chas - N5UL
Hobbs, NM
          
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