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Re: Topband: In search of resonance

To: topband@contesting.com
Subject: Re: Topband: In search of resonance
From: Herbert Schonbohm <herbert.schoenbohm@gmail.com>
Date: Tue, 25 Feb 2014 12:52:13 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
On 1/30/2014 11:03 PM, Carl Braun wrote:
If I can't get the antenna to resonate using the L I'd say that I'd consider 
shunt feeding the tower and work out an (omega) matching scheme to match the 
tower to my target freq.  If that's the case, do I mount my upper shunt arm on 
the tower at 67' or at 90'?

Can I run a single drop wire into my panel and then switch the feed between two 
matching networks?  One for 160 and one for 80?

Please advise

Thanks

Carl AG6X



Carl,

Why not just run a slant wire to your shack and feed the bottom against a ground system through an ATU. Don't expect any real drama on 80 meters as the tower is probably to long electrically. ut a slant on any frequency could be modeled to see what you choices are. The only way this could change if you made a decoupling sleeve on the tower so the radiator appear to be between 1/4 and 3/8 wave length. It can work as a duo bander but it will require some extra work and a good vacuum switch since the voltages may be high at the in/out switch point. Some directive in the direction of the slant may occur but it should be be slight. As far as a drop wire shunt is concerned: There should not be any advantage of having the drop wire shunt arm much higher than the approximated sweet point for you tower.


Herb Schoenbohm, KV4FZ

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