[TowerTalk] Shunt fed tower for 80M

[Ron Chambers]

Got a 60ft 25G tower with a small tribander and 40m rotatable dipole at
the top......I hooked up a fairly typical* (38 ft of wire 15" from tower,
125pf series capacitor) shunt feed arrangement and found a nice match
(l.2:1) at 3.880mhz, with about 60khz between 2:1 points.....but at
3.525mhz it is about 6:1 or worse......

Being 99% CW  I have tried in vain to repeat this 'nice' match down at
3.525mhz....I have adjusted the length of the wire and the distance from
the tower, adjusting the capacitor each time......The 'best' I can do is
achieve about 3:1 at 3.525mhz.....

What am I missing?

* The computer program said 29ft of wire should do it.....At that length,
the 'best' match was achieved at 4.800mhz!!...So I moved the attachment
point up the tower.... the freq lowered till it seemed to reach a plateau of
3.880mhz....moving further up the tower makes no difference.....

Ron
K5PN

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