> Hello - I am intending on putting up a tower at my new home in Bandon,
Or. I
have 40 acres and it is surrounded with 70 foot high timber. When I saw the
layout and I thought I would put up a 150ft tower. I will not be doing this
often, so I want to put it up once and have it stand. General TIA wind
ratings for the county are 80mph, with "special areas" - and of course I am
in one of those special areas which has ratings of 110mph.
> Right off the bat I excluded putting up a Rohn 25G, opting instead for
a 45G
- but then a buddy of mine said that he would go for a 55g.
> I intend on putting up a big M2 or Mosley multi-bander (15sqft) and a 40
meter three element (20 sqft).
> I know of folks that have these sorts of setups, but when I take a look
at
the Rohn wind load I was really surprised.
> A Rohn 45 150 foot 130mph rev G / 110 mph Rev F shows it will only allow
10.4 sqft of load.
> So, I thought a Rohn 55 would do the trick but it shows:
> Rohn 55 150 foot 130mph rev G / 110 mph Rev F shows it will only allow
16.6
sqft of load.
> Are the specs WAY too conservative or should I put up a really HUGE
tower to
accommodate what I want to do?
Hiya, Chris --
You should get out like gangbusters since you're close to saltwater.
First, you should read my UP THE TOWER book - The Complete Guide To
Tower Construction - available from many ham dealers and will answer just
about all of your questions including some you haven't thought of yet.
In it you would find that in the General Notes is a note that says
that Rohn has deducted 8.0 square feet for symmetrical mounts which is common
in commercial applications. If you add the 8.0 sq.ft. back in, you'll see
that you'll have significantly more tower capacity. You're welcome.
Also, please DO NOT install a Mosley antenna. In a landmark tribander
on-the-air test that N0AX and I conducted, we found that Mosley (Measly?)
antennas under-perfom the competition. One model even had negative gain on
one band. The whole report is available from championradio.com and will give
you a complete picture of antenna performance.
I have a customer in Bandon - Dan Bissell, W7WVF - you may know him.
I'll be down there in the next few months to do some work for him so maybe
we can get together then.
I've worked on over 260 amateur and dozens of commercial sites so have
plenty of experience.
And congratulations for using TowerTalk. It's saved many a newbie
tower owner lots of grief thru the wealth of experience of the members.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for amateurs
Cell: 206-890-4188
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