Topband: Fire tower as support for 1/4-wave sloper

Greg - ZL3IX zl3ix at
Wed Nov 22 12:08:42 EST 2006

John Harper wrote:
> Hello,
> I have obtained permission to operate from what I hope will be an ideal 
> location (better than my home QTH) for the upcoming ARRL 160 Meter Contest - 
> a fire tower-like tower, 90 feet tall way up on a hilltop above the 
> surrounding terrain with a building at the base with all the creature 
> comforts. My plan is to put up a sloper. Although I've never used a sloper 
> before on any band, I understand they can be hit or miss as far as 
> performance goes.
> My question is:
> To achieve resonance, is it better to trim the length of the sloper or 
> experiment with the height of where it's fed on the tower?The tower in 
> question is steel, about 20' on a side with a steel stairway going up the 
> center.
Hi John,

Having used a sloper from ZL for 4 years, I changed over to a top drive 
arrangement.  The latter gave me a 3 dB improvement over the sloper.  
You may want to try out top drive.

If os, run the coax up the tower, and connect the screen to the top of 
the tower.  Make a loading coil and attach the inner of the coax to one 
end of the coil.  Attach the other end of the coil to a capacity hat 
made from some wire.  Tune to resonance.

Which ever antenna you choose, don't forget to attach some radials to 
the base of the tower.

73, Greg, ZL3IX

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