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Re: [TowerTalk] Hy-gain 204BA element changes...

To: <>
Subject: Re: [TowerTalk] Hy-gain 204BA element changes...
From: "Clay Curtiss W7CE" <>
Reply-to: Clay Curtiss W7CE <>
Date: Fri, 17 Feb 2006 22:03:36 -0800
List-post: <>
----- Original Message ----- 
From: "Dino Darling" <>
> What I would like to do is move the 1 1/8" tube in one additional
> inch (3" overlap instead of 2") and compensate for the shorter
> half-element by pulling the 7/8" out...but by how much, I don't
> know.  I have 2 1/2" to play with since it is only floating in
> air.  This is where I need your help!  I do know that 1" of 1 1/8
> requires more than 1" of 7/8" to compensate.
Making the 1-1/8" in tubes shorter and the 7/8" tube longer will increase
your resonant frequency.  However since you're only talking 1" change on
both elements. the effect will be minimal.  Just for fun, I ran a simulation
a 4el, 34' boom design that I'm playing with (non-tapered elements).  It's
the same as your antenna, but the results should be similar.  I reduced the
length of all elements by 1" which is extreme overkill for the change that
you are making.  The resonant frequency went up 30 kHz and all of the
other characteristics were unchanged.  The change you're talking about
will proably require that you lengthen the total element length by less than
1/8".  If you leave the total length alone your resonant frequncy might move
5 kHz.  We can't predict the resonant frequency that accurately.  Towers,
wires, other antennas ant height above ground will impact it more than that.

> why mess with it.  My 1 1/8" tubes are bent at the 2" mark and I'd
> guess it would be better if there was a bit more overlap.
If the 1-1/8" tubes are bent at the 2" mark, they will probably bend at the
3" mark.
Are the tubes that the 1-1/8" tubes slide into bent (the tube that is taking
all the
weight of the 1-1/8" tubes)?

> One of these days I may get a copy of YO and learn to use it, or
> build a NEC file for use in Eznec, but for now, I'm useless!  :-)
YO is difficult to get.  I wrote to K6STI in December trying to purchase of
of it and his coil calculator.  He wrote back saying (and I quote):

    "Due to widespread software piracy, I no longer supply software to
     hams.  I quit the business in 1999."

Let us know how your project turns out.

Clay  W7CE


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