[Antennas] T match

Tue, 24 Jun 2003 16:50:42 -0700 (PDT)

Groovy, I like it, thanks.

--- David Robbins K1TTT <[email protected]> wrote:
> Ok, if you are really into balanced line that makes
> T matches easy...
> I'm having a hard time trying to picture what would
> happen with a split
> de fed that way.  Normally I would look at an old
> telrex design where
> the de is through the boom and the T sides are fed
> with a coax balun...
> the shields of all the coax are connected to the
> boom in this case,
> though theoretically they probably don't have to
> be... and the center of
> the de is of course connected to the boom so they
> are all theoretically
> at the same 'ground' potential.  Now feeding it with
> balanced line to
> the T should theoretically result in the same
> condition where the split
> ends of the de have essentially zero voltage... I
> know this should be
> true, but still I would connect the split ends to
> the boom.  If nothing
> else this would provide a dc ground for the de and
> may reduce static
> build up and provide a path for lightning besides
> down the feedline to
> the shack.
> 
> I do rather like the telrex feed system, simple
> construction
> mechanically and electrically with no capacitors to
> bother with, and a
> simple 1/2 wave coax balun to get a 50 ohm coax
> feed... and all at dc
> ground.
> 
> 
> David Robbins K1TTT
> e-mail: mailto:[email protected]
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>  
> 
> > -----Original Message-----
> > From: [email protected]
> [mailto:antennas-
> > [email protected]] On Behalf Of Steve L.
> > Sent: Tuesday, June 24, 2003 22:22
> > To: David Robbins K1TTT; [email protected]
> > Subject: RE: [Antennas] T match
> > 
> > Hi,
> > 
> > To be more specific, I normally design and build
> > monoband HF yagis with a continuous DE and T-match
> to
> > get 200Ohms and feed with 450 Ohm balanced line to
> a
> > transmatch in the shack.
> > 
> > I have an existing yagi with a split DE that I
> want to
> > feed in this way by adding a T match and feeding
> w/
> > balance line. Alternately I'm looking for the best
> way
> > to use balanced line and feed this antenna.
> > 
> > I go for a 200 Ohm feedpoint to allow using a 4:1
> > balun at the feedpoint and feeding with coax as an
> > option (although I never actually DO this).
> > 
> > 73, Steve N4SL
> > 
> > --- David Robbins K1TTT <[email protected]> wrote:
> > > >
> > > > I've used T matches on Yagis quite a bit with
> good
> > > > success, but always with a continuous DE, not
> > > split.
> > > >
> > > > Hmmm.... can I use a T match on a split DE?
> > >
> > > I suppose you probably could.  It would be more
> > > trouble construction
> > > wise than just having a solid element and
> shouldn't
> > > really change the
> > > performance as the inside end would essentially
> be
> > > grounded on each side
> > > but through the coax instead of directly to the
> > > boom..
> > >
> > > David Robbins K1TTT
> > > e-mail: mailto:[email protected]
> > > web: http://www.k1ttt.net
> > > AR-Cluster node: 145.69MHz or
> telnet://dxc.k1ttt.net
> > >
> > >
> > >
> > >
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> [email protected]
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> 

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