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Author Topic: 40' freestanding tower recommendations?  (Read 818 times)
NORTHCOUNTRY
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« on: January 05, 2007, 09:18:30 AM »

In simple terms I want to put up a 40' tower that is free standing. On top would be basic tribander and maybe a vhf vertical on top of that.  The location is suceptable to pretty high winds.

I do not want nor have the property to permit guy wires.

I understand that some people attach the tower to the house this is a good possibility for me. How does that enhance the freestanding height of the tower?

What length of mast extending above the 40' tower structure is practical to consider?
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W5GA
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« Reply #1 on: January 05, 2007, 09:39:01 AM »

If you'll do a search on Ebay, you'll see lots and lots of free standing towers (search "antenna tower").  Attaching it to the house is something usually done with guyed towers, and it changes where the first guy attachment is in relation to the height of the tower.  If the tower is short enough, it may eliminate the need for guys, depending on tower type.  For a typical Rohn 25 type tower, I wouldn't want to be climbing on it at 40' with only a house bracket.  Too much of a wet noodle, and probably inviting disaster.  Rohn 45 would probably be ok at this height, though.

As for mast length, all towers are rated as to how much wind load they can support.  This rating assumes the antenna will be installed right at the top of the tower with no more gap between the two than what is necessary to allow rotation (maybe a couple of inches?)  The longer the mast, the more derating in the allowable wind load.  Also, the longer the mast, the stronger the mast material needs to be.  It really depends on what tower you decide on.
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N3OX
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« Reply #2 on: January 05, 2007, 09:52:32 AM »

Tom, you got a tower already?  Are PG County permitting requirements easy?

Montgomery county, from what I hear is a real pain in the you-know-what, and requires engineering analysis.

I don't know if that's bled over here yet... but if PG county requires you to hire an engineer, they'll tell you *all* you need to know (and more ;-) )

Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N4ZZK
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« Reply #3 on: January 05, 2007, 10:11:56 AM »

Check out the U S Towers MA-40.  It can be freestanding or attached to the house eaves.  I also have their freestanding MA-850.

My MA-40 is about 10 years old and came with the house bracket which I have used in the past but I use it freestanding currently.  

pix at www.nn4zz.com

73...Al
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NORTHCOUNTRY
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« Reply #4 on: January 05, 2007, 10:28:56 AM »

What type of engineering analysis and permit is required?  

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NORTHCOUNTRY
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« Reply #5 on: January 05, 2007, 10:34:30 AM »

in reply to n4zzk:

thanks and I looked at the tower you show picture of with the 10/15/20 quad on it.  the picture is helpful in visualizing the aesthetic implications.

I am wondering who makes that quad or did you make it yourself?

how would you say the quad fairs compared to a tribander in a high wind location?
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N3OX
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« Reply #6 on: January 05, 2007, 01:19:05 PM »

"What type of engineering analysis and permit is required? "

Not sure... I'm using all temporary structures and renting so I haven't looked into it.

As a homeowner and prospective tower erecter you might want to ;-)

73,
Dan
Riverdale, MD
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Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N4ZZK
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« Reply #7 on: January 05, 2007, 01:25:43 PM »

The quad is made by Cubex.  Mine has fared well over the last 8 years or so but most would say they are not going to suvive high winds and bad weather (icing) as well as a yagi.

I do think they have some advantages though.  They tend to be quieter antennas.  While it's debated often I think a 20/15/10 quad works a little better that a yagi when you are limited to a 40 foot tower (as opposed to say 70 feet).  

73...Al
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WB2WIK
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« Reply #8 on: January 05, 2007, 01:59:12 PM »

I sure know nothing about your county, and their website doesn't reveal much:

http://www.goprincegeorgescounty.com/Government/BoardsCommissions/index.asp?nivel=subfoldmenu(0,0)

I tried to look up zoning ordinances, as these are public and posted on many city and county websites, but evidently not on this one.  You might contact the zoning board via telephone or in person (visit) and get a copy of anything pertinent to the erection of a tower.  If you're lucky, there won't be anything, because they won't care!  But most aren't quite that lucky.

In *most* places, and the places I've lived, at least a building permit is required for a permanent tower installation.  The permit application is completed and filed, and usually a fee paid.  Then, they let you know what else is required: Often, a site inspection by a building & safety engineer who reviews the proposed installation and has the authority to approve it or not.  If "yes," you get the permit and you're good to go; if "no," you get a chance to appeal, usually via a variance or conditional use permit.  That might (not always) require a public hearing.

This all sounds more daunting than it really is.  I've been through it a lot of times, and I've installed a lot of towers.

A 40' freestanding tower isn't a big deal and often falls under the height limit requiring any variance; but they might want to inspect the foundation (footing) for the tower, the manufacturer's specification for the tower, its wind load rating at 70 mph or 80 mph (depends where you are) and the load you intend to place on it.  This is where buying a "new" tower often helps a lot, because all that documentation (including signed & dated blueprints with a P.E. stamp) is available, whereas on "used" towers, it's often not.

I prefer freestanding telescoping towers, myself.  No guy wires, no brackets, just a concrete foundation and the tower itself.  Allows one to crank it up or down as needed, and these models can be *VERY* strong -- they have to be, since they're self-supporting.

WB2WIK/6
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N3OX
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« Reply #9 on: January 05, 2007, 05:06:23 PM »

The MDC section manager, WI3N, lives in Laurel.  He probably knows something about this.

Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KB9CRY
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« Reply #10 on: January 05, 2007, 06:56:56 PM »

Trylon Towers would work as well as AN Wireless.  Those are the only two that I would consider not including crankups.

Phil
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