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## [TowerTalk] stacking antennas & Rohn specs

 To: [TowerTalk] stacking antennas & Rohn specs k4isv@mikwest1.westky.com (k4isv@mikwest1.westky.com) Tue, 15 Jul 1997 02:45:21 +0000
 ```To: > Date: Sun, 13 Jul 1997 02:09:57 -0700 (PDT) > To: Bruce Makas > From: w7ni@teleport.com (Stan Griffiths) > Subject: Re: [TowerTalk] stacking antennas & Rohn specs > Cc: towertalk@contesting.com > >I am installing several Rohn towers and want to stack antennas on the > towers. Being a "good" amateur engineer, I intend to follow the specs in the > Rohn catalog. My question is about the allowable projected area that is > called out by Rohn. For example, if I were to put up 130 foot of Rohn 45G in > a 90 mph area (coastal Maine), the book says that 12.3 sq ft of projected > area of round elements is allowable (C870478R1). I assume that is at the top > of the 130 foot tower. > > > >Now, I want to stack antennas; say one at 60 feet, one at 100 feet and one > at 130 feet. How do I calculate what is the allowable sq footage? Is it as > simple as summing the moment arms (height x sq ft of each antenna compared > against 130 ft x 12.3 sq ft) or is it more complicated? > > > >For example, a 205CA specs out at 9 sq ft, I would hope that I could put at > least three of these, and 3 155CA's (5.2 feet each) on the tower, but it > doesn't look it. > > > > ((60x9)+(100x9)+(130x9)) > (130x12.3) ........... for just the > > 205CA's > > > >If this is true, how can anyone stack more than 3 large antenna's per > tower? Even a 55G installation only allows 14.8 sq ft @ 130 feet. > > > >What am I doing wrong? > > > >Thanks in advance for your ongoing support of my antenna project. 73, Bruce > > Hi Bruce, > > I have yet to meet the guy on this reflector who will admit he knows how to > properly answer your question. Rohn can answer it for you but it will cost > you lots of money, somewhere in the thousands of dollars. It takes an > experienced structural engineer to really engineer a project of the kind you > are describing. > > But, you say, you know other hams who have put up such installations. How > did they determine they were safe? I'll bet they didn't. Most of them have > looked at similar installation that have been up a long time so they used > them as good examples. They have also studied all the data they could get > on failures so they would know what to avoid doing. You either have to step > up to a large engineering bill or take some risk. Studying what has worked > what hasn't will minimize your risk. > > Good luck. > > Stan w7ni@teleport.com > > > -- > FAQ on WWW: http://www.contesting.com/towertalkfaq.html > Submissions: towertalk@contesting.com > Administrative requests: towertalk-REQUEST@contesting.com > Problems: owner-towertalk@contesting.com > Search: http://www.contesting.com/km9p/search Since I have addressed this before I will be brief: on a 190ft rohn 45 i have 2 5 ele 20m - 44 ft boom es 3 4 ele on 26 ft booms; on a rohn 25 180 ft i have 2 6 ele on 40 ft booms and 6 4 ele on 22 ft on 10m i have 4 6 ele on 26 ft booms- on 40m full size 3 ele over a klm 4 ele on a rohn 45 up 170 ft--- my point is simply to say these towers will hold up much much much more than you would expect with proper guying... no engineering-- i just keep adding antennas 73 es have some fun > -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com Search: http://www.contesting.com/km9p/search ```
 Current Thread [TowerTalk] stacking antennas & Rohn specs, Bruce Makas [TowerTalk] stacking antennas & Rohn specs, K7LXC@aol.com [TowerTalk] stacking antennas & Rohn specs, Stan Griffiths [TowerTalk] stacking antennas & Rohn specs, T. A. Russell [TowerTalk] stacking antennas & Rohn specs, k4isv@mikwest1.westky.com <= [TowerTalk] stacking antennas & Rohn specs, Dick Flanagan [TowerTalk] stacking antennas & Rohn specs, K7LXC@aol.com [TowerTalk] stacking antennas & Rohn specs, K7LXC@aol.com [TowerTalk] stacking antennas & Rohn specs, k4isv@mikwest1.westky.com Message not available[TowerTalk] stacking antennas & Rohn specs, k4isv@mikwest1.westky.com