Re: [TowerTalk] Delta Loop Info and Opinions?

[Joe Giacobello <k2xx@swva.net>]

Tom, thanks again, and it's interesting you brought up the issue of the 
balun on the input of an unbalanced tuner.  I have some comments about 
that, but I'm going out of town very early tomorrow (Ivan permitting) 
and will get back to you when I return. BTW, I had some correspondence 
with W7EL on the subject and (I think) I copied you.

Will be back to you later.

73 and thanks for help!

Joe

Tom Rauch wrote:

> > Tom, thanks for your reply.  In all honesty when I read
> >    
> the article, it
>  
>
> > made sense to me because if one were trying to minimize
> >    
> the interaction
>  
>
> > between the delta and the tower, minimizing the RF current
> >    
> flow on the
>  
>
> > tower seemed logical.  I went back and rechecked the
> >    
> article to make
>  
>
> > sure I hadn't gotten it backwards, and I hadn't.  I am
> >    
> going to have to
>  
>
> > reconsider the whole issue in light of your explanation.
> >    
>
> I have something on my webpage at:
>
> http://www.w8ji.com/detuning_towers.htm
>
> Basically the drop forms a parallel tuned circuit that
> isolates the section. When you measure the cirrect in the
> drop wire, which is what I believe the book suggests, if you
> set the shunt wire current to zero the shunt wire has NO
> effect!!!
>
> Going from the top of a structure to ground, or if the tower
> is long in terms of 1/4 wl sections, the results are
> different. In that case the only reliable way to detune is
> to measure the overall effect of the structure on pattern or
> re-radiation with a FS meter.
>
> Anyone who has worked with resonant systems knows the
> circulating current is maximum when the system is resonant.
> For example a trap isolating two sections of an antenna has
> maximum current circulating in the trap when the loop
> through the inductor and capacitor forming the trap has
> highest current!
>
> Intuitively, as another example, people think moving a balun
> to the input of a floating network makes balance better and
> reduces balun heating. That isn't correct, yet everyone
> believes it. This is why we have to take everything we read
> with a bit of caution, and not go by first instinct.
>
>  
>
> > BTW, I did mention that the deltas were for 30 and 40M and
> >    
> I had planned
>  
>
> > on vertically polarizing them and feeding them with
> >    
> balanced line.  The
>  
>
> > reasons for using the loops are that I am looking for some
> >    
> gain and
>  
>
> > directionality on 30 and 40M with a low takeoff angle,
> >    
> simplicity and I
>  
>
> > have a lot of experience with quad loops.
> >    
>
> Must have missed that. Loops reduce height requirements, and
> that's a good thing. Just be careful with the feedline. The
> feedline can be more of a worry to decouple than the tower
> supporting the loop.
>
> I'd install it first, and worry about problems later if they
> show up.
>
> 73 Tom
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>
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>
>  
_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

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