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[Towertalk] Can my 40' tower be a 160m vertical?

To: <towertalk@contesting.com>
Subject: [Towertalk] Can my 40' tower be a 160m vertical?
From: n4kg@juno.com (n4kg@juno.com)
Date: Thu, 26 Sep 2002 16:59:08 -0600
YES.  IF you can get 1/4 WL (or more) then 30 to 60 radials is
beneficial.  IF you are limited to 1/8 WL long radials, there is
virtually NO benefit above 15 radials.

Tom  N4KG

On Thu, 26 Sep 2002 14:47:07 US/Eastern jperalta@tampabay.rr.com writes:
> Aren't radials also needed to make the shunt fed tower work 
> efficiently? If so 
> what would be the correct length and how many for a respectable 
> installation?
> 
> Julio, W4hy
> 
> 
> 
> > Jim:
> > 
> >      I agree with Phil's recommendations on Jeff's book.  You can 
> get it
> > from ARRL.  I based my Trylon 64's shunt feed on Jeff's design.  
> The key is
> > to have something as a capacitive load at or near the tower top to 
> make the
> > tower appear electrically longer than it is physically.  Your 
> Yagi/40M
> > add-on ought to be a pretty good load.
> > 
> >      Many on this reflector would recommend modeling, but I'd say 
> try it and
> > let us all know.  The feed is nothing more than a wire from the 
> bottom of
> > the tower and connected near the top, keeping it a couple of feet 
> away from
> > the tower itself (I used PVC tubing as spacer material).  Then you 
> feed the
> > bottom of the wire through a variable transmitting cap of some 
> fairly large
> > value in series with the coax center; I keep the cap insulated 
> from ground
> > by mounting it in a plastic weather enclosure (a plastic shoe box 
> from
> > K-mart).  The coax shield gets connected to the tower legs and 
> ground
> > radials.  Tune the cap for min SWR and call CQ.
> > 
> >      BTW, the sloper might have an impact on your ability to shunt 
> feed the
> > tower.  If you can't get the tower to load, you might want to 
> remove the
> > sloper and try again.  (I haven't modeled this, so I'm guessing.)
> > 
> > GL es 73 de
> > Gene Smar  AD3F
> > 
> 
> 
> 
> 
> _______________________________________________
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