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Re: Topband: 2 element vertical for 80m with 1/8wavelength

To: <topband@contesting.com>
Subject: Re: Topband: 2 element vertical for 80m with 1/8wavelength
From: "Ed Sawyer" <sawyered@earthlink.net>
Reply-to: sawyered@earthlink.net
Date: Tue, 19 Apr 2016 14:13:49 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I can't speak to verticals spaced that tightly but I can speak to dipoles
spaced that tightly.  I have 2 phased half wave dipoles spaced 1/8 apart and
fed 180 degs out of phase.  I get nice gain (looks like a solid S unit or
~5db as expected from on the air tests).  But the bandwidth has to be
managed.  The 2:1 BW is no more than 125khz.  No issue on CW when I use my
CW stub setting but a definite issue going from 3850 down to 3600 in an SSB
contest.

 

And additionally, the impedance is very difficult to match.  I have used
open wire line feeders and found the 50 Ohm matching point to tap off - I
believe about 3/8 wave down the feed line for each element.  The impedance
changes significantly as you shift frequency.

 

I have opted to use a remote tuner at the connection point of the 2 feeders
to get full band SSB coverage which works slick.

 

The verticals will present different impedances than the dipoles, but I
would think the complexity of the 1/8 wave separation and phasing would be a
similar bronco to ride.

 

By the way it's a "kick @#s" antenna to EU.  I often get "loudest USA
station" reports when running in a SSB DX contest.

 

73

 

Ed  N1UR

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