Topband: KLM antennas on shunt fed towers

[Tom W8JI]

> Anyone have problems running a KLM antenna with the 4:! balun and elements 
> insulated from the boom (stock KLM config) on a shunt fed tower for 160? I 
> ask because I have a 6 element 10 on the top of my shunt fed tower and 
> now, after running a kw on 160, the antenna's swr has gone over 2:1 where 
> before it was pretty flat at about 1.2:1 or so. Any ideas?

You probably ruined the balun from 160 current. The best cure would be 
installation of RF chokes from elements to boom on all of the elements. 
Anything over a few dozen ohms on 10 meters works for the parasitic 
elements. They are not critical.

For 10 meters, I would use a good 4:1 voltage balun with the coax grounded 
to the boom, or you can use a 4:1 current balun if you use a center tapped 
choke of at least 1000 ohms and less than 2000 ohms on ten meters with tight 
mutual coupling across the winding.

It would not be difficult to build some.

Remember the half-wave of coax makes a voltage balun, so you might as well 
just save space and get more bandwidth by using a standard compact 4:1 
voltage balun.

73 Tom