Gary,
You are planning a very fine installation there! I have a couple of suggestions
for you, based on my similar installation.
That is a LOT of antenna load you will be installing. You should probably be
somewhat more conservative than what you've described. Here are my thoughts:
- Put at least 8-10 feet of your mast inside the tower. 18 feet is way too
much out the top. This is the BIG weakness in your current plan.
- Did you mention what size and material your mast will be? Seriously consider
a 3" Chromoly mast. Make sure it is galvanized. You will not regret this, and
the OR-2800 can handle it.
- Although Rohn only says you need two levels of guys for an 80 foot tower, go
to three sets. This will strengthen the tower for your increased load, and it
may give you a better spot to place your side-mounted antenna[s]
- Use a TA45 guy bracket [aka star guy] at the top of the tower. Rohn 45G will
definitely twist in high winds with that much load on top. The guy bracket will
hold the tower firmly in place.
- Consider a different mix of antennas - WARC on top of the mast and the
OB16-3 lower on the mast. This will reduce the wind load on the mast. Add a big
40m yagi on a ring rotor right at the top set of guys. Tower height of 90 feet
would be better for this setup. I think your budget might not change much with
this mix.
- Put your small tribander at about 60 feet on a sidemount or ring rotor.
You will have an awesome setup if you take care to be somewhat conservative.
On your other questions, I think W9GE has givien you a very good set of
realistic answers.
Check out my tower with a lot of relevant information at www.k1ir.com. Click on
all the links discussing the 40m yagi installation. Buy your guy bracket from
Norm's Fab. He did a great job for me.
73,
Jim K1IR
Jim Idelson K1IR
email k1ir at k1ir.com
web http://www.k1ir.com
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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