You should really model this on EZNEC.
Having done this many times, I can say
that the length of the vertical plus the
length of one of the top wires should be
about 120 feet to hit exact 1830 resonance
without a loading coil. However,
there is absolutely no compelling reason why
this is necessary. A loading/matching coil
is far more convenient if you keep the wire
length to 25 feet. Therefore, it should
never be necessary to put it up and down a
bunch of times to get it "just right". There
is no "just right" with respect to the antenna
proper. Use the taps on the coil to do the trimming
to make the system just right. This has been
discussed many times on this reflector.
Rick N6RK
On 2/3/2018 5:20 PM, Bill via TowerTalk wrote:
Planning on putting up a 160 vertical, but of course a 1/4 wave vertical is out
of the question here in HI since we have a height limitation.
Here's the question: I'm putting up around 50 feet of 3 inch aluminum tubing (left over from various antenna takedowns). I plan on putting up on top of that around another 10 or 15 feet of smaller diameter stinger for a total height of around 60-65 feet. I obviously need to make up for the lack of height and I was planning on making a top hat of four wires coming down from the top of the antenna at around a 45 degree angle. The problem is how long to make each of those wires. My guess is around 25 feet based on my past experience in making Tee-topped 80 meter verticals. However, it is only a guess and I don't feel like yanking the 3 inch pipe up and down a bunch of times to get it just right.
I know some trimming will be necessary since this is not an exact science. I just need an educated guess for where to start with the length. Any ideas?
Bill K4XS/KH7XS
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