Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Mounting a Tower on a Deck (Porch)  (Read 326 times)
K8LEC
Member

Posts: 64




Ignore
« on: May 08, 2004, 06:50:15 PM »

I've recently purchased 40ft of Rohn 20G tower that I plan to use for a vertical.  My question is, has anyone had any luck mounting a tower like 20 or 25G on top of a wooden deck?  My deck is extremely strong and solidly built and is on the 1st story, however is over a walkout basement, which is why I want to use it possibly.  Obviously placing the tower at the level of the walkout will make me loose 10-15ft of tower height.  

I know you can put towers on roofs, so I don't see why it wouldn't work, but I thought I'd get some input from anyone who has some thoughts on that idea. Thanks in advance.

73's
K8LEC
Lars
Logged
K0RFD
Member

Posts: 1368




Ignore
« Reply #1 on: May 08, 2004, 07:02:45 PM »

Maybe if you guy it, but man that's a pretty long lever.  I rather suspect that a strong wind with that kind of moment will generate a bit more force than your decking can resist.

I'd stick with building codes and with the manufacturer's guidance on this one.  Because if you don't and something happens, your insurance will never pay off.
Logged
W7DJM
Member

Posts: 1




Ignore
« Reply #2 on: May 08, 2004, 09:37:22 PM »

I'll leave it to the younger math whiz's to calculate the forces here, but my first answer is NO WAY.   Do you understand, first of all, that the forces of the wind and guys are transferred STRAIGHT DOWN on the base of the tower.  In other words, in a high wind, not only will you have

the weight of the tower
the weight of all antennas
the weight of all feedlines
the weight of all control cables
the static weight of part of the guys and hardware

you will have the DOWNWARD force caused by the STATIC tension of the guys, which is going to depend on the number of guys, how close they are to the base of the tower, and how tight they are
PLUS
the downward force caused by the guys transferring the wind side force downward.

The closer the guys are to the base of the tower, the stronger this force will be.

My guess is, that if this is a typical residential deck, any inspector in the world would take one look at that and become ill.
Logged
KR4BD
Member

Posts: 213




Ignore
« Reply #3 on: May 08, 2004, 11:16:44 PM »

Another concern I would have is GROUNDING.  With your tower sitting on a wooden balcony, I would think it would be a fire hazard should it get hit by lightning.

Tom, KR4BD
Logged
N3NDW
Member

Posts: 46




Ignore
« Reply #4 on: May 09, 2004, 07:53:44 AM »

Just do the math. They probably require a minimum of 3-4 cy of concrete to anchor the tower in the ground. considering that the concrete weighs 4000# per yard, the deck is not heavy, or strong enough to support the tower.
Logged
K1CJS
Member

Posts: 5830




Ignore
« Reply #5 on: May 09, 2004, 08:25:02 AM »

Hey man, don't even try it!  Bite the bullit and get another 20 feet of tower if the height is that important to you.  And don't skimp on the concrete footing for the tower, either.  That's the only safe and secure way to put a tower up.
Logged
K8LEC
Member

Posts: 64




Ignore
« Reply #6 on: May 09, 2004, 10:19:27 AM »

Thanks for all the info.  Hadn't even thought of some of the stuff you all mentioned!  First attempt at a tower, hence the small 20G type and only 40', so my ignorance has shown.  We'll stick to a typical concrete structure on the ground!!!  Thanks to all!

73's
Lars
K8LEC
Logged
WB4QNG
Member

Posts: 359




Ignore
« Reply #7 on: May 09, 2004, 10:40:01 PM »

Don't listen to these guys go for it. It could last a life time. Then again you could have a short life when the thing falls on you while your sunning yourself on your deck. Better to go the extra mile and be safe with these things than be sorry.
Terry
WB4QNG
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!