Topband: New Antenna, Need Advice

Jim Brown jim at
Sun Sep 17 11:07:24 EDT 2006

I've successfully moved my top-loaded vertical from Chicago to 
Santa Cruz.

The vertical is really an 80/40 dipole with loading coils to make 
it resonate on 80, and fed with old 72 ohm KW twinlead and no 
balun at the top. On 40, the loading coils self resonate and act 
as traps. When I load it as a dipole, I use a balun at the antenna 
tuner. When I load it as a vertical, I tie both sides of the 
feedline together and load it against radials. 

Here in Santa Cruz, the feedline is almost straight up and the 
dipole section is in the clear. That makes it a lot closer to 
ideal, so it loads like a quarter wave on 160. So far I have 13 
1/8 wavelength radials under it, and bought the wire yesterday to 
do another 12 or so in the next few days. Z at the feedpoint is 
about 32 + j5 at 1790 kHz. It also seems to talk pretty well based 
on only one evening of operating. 

Another nice thing is that it is loads and talks well for DX on 
40. With the loading coils it's acting like a 3/4 wave vertical on 

My question is with respect to loading it on 80. In Chicago, it 
was far enough from an ideal full wave that my tuner handled it 
just fine, but here in Santa Cruz where it's almost a perfect half 
wave (with the loading coils), the Z is far too high. What's the 
best way to load it on 80?  It's only about 25 ft from the shack, 
so a ladder line stub as a transformer is not very practical. 


Jim K9YC

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