Re: Topband: vertical 160/80m

[Roger D Johnson <n1rj@adelphia.net>]

I have used several versions of this antenna over the years. The
last being the Titanex V-160s. It's approximately 3/8 wavelength
on 80m so the base impedance isn't too high. I also discovered
that there is an easy way to match the antenna on both bands. I
use an inductor from antenna base to ground and a motor driven
series capacitor from antenna base to the feedline. I don't remember
the exact values but I think the inductor is about 12 uH and the series 
cap is an old 500 pf motor driven cap from a Heathkit antenna SA-2550 
antenna matcher. The neat thing is that the antenna is tuned on both 
bands at once. In my Titanex installation, I could adjust it so it was
resonant on the DX portion of 160m and the 80m DX window at the same 
time. Only when I wanted to operate 80m CW did I have to retune the 
capacitor! Of course, it took a bit of fiddling with the inductor
value to achieve this result and it will depend on the actual values
of base impedance on your particular antenna.

73 and DX, Roger




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