[TowerTalk] Horizontal loop and balun

[Tom Rauch]

> A balun work's best when it see's a pure resistance, or nearly so.  A
> balun at the end of a piece of coax, feeding a length of balanced line
> that feeds an antenna, will almost be guaranteed to see a reactive load.

A choke balun cares less if the load is reactive, only voltage baluns 
(like the W2FMI style) are load impedance critical.
 
> A better idea would be to place the balun at the input of a balanced
> tuner.  If there are difficulties in bringing in the balanced line to the
> tuner, then a small section of shielded balanced line can be employed.

Placing a choke balun at the input of a tuner does nothing for 
balancing of the system, although it does reduce differential mode 
stress on the balun (which usually isn't a problem anyway if you 
use a properly constructed choke balun).

After some discussion of this in another antenna forum, Roy 
Lewallen (W7EL) did an analysis and confirmed this.




73, Tom W8JI
W8JI@contesting.com 

List Sponsor: Are you thinking about installing a tower this summer? Call us
for information on our fabulous Trylon Titan self-supporting towers - up to
96-feet for less than $2000! at 888-833-3104 <A HREF="http://www.ChampionRadio.com">
www.ChampionRadio.com</A>

-----
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com