Larry,
I think the formula for this is in ON4UN's books. I had a 100-ft tower and if I
recall his example for this height was a top hat of 6 spokes with a perimeter
wire of 10 feet diameter. Instead I used a 4-el. 6 meter yagi on a 10 or 12-ft
boom that got it pretty close -- needed a couple feet of linear loading at the
base to bring it into resonance. This was a series-fed tower.
73/Jon AA1K
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Larry - K1UO
Sent: Wednesday, February 4, 2015 10:27 AM
To: Topband Reflector
Subject: Topband: Top Loading wires
Could someone tell me the length of top loading wires (4 wires planned) needed
to add to the top of a base insulated 90 foot Rohn 25g tower to maximize the
radiation resistance on 160 meters. I understand there is a point of
diminishing returns on the top loading lengths. The 4 wire angles will be
around 45 degrees or as close as possible. If I knew how to model ,or even
had a modeling program, I would attempt this already relatively simple task to
many.
From 50+ years of practical experience, I am ‘guessing’ maybe 28 feet long each?
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