[TowerTalk] Bracketed 45G

[Kevin Hemsley]

Steve (K7LXC) wrote:
> My first question is what  heights it's going to be housebracketed at 
> and how much tower will be  above the top bracket (Rohn specs call for 2 
> brackets)? The Rohn specs allow 14  feet above the top bracket and will take 
> aproximately 30 square feet at 75 MPH.  (Obviously you can go up a little higher 
> while de-rating the capacity.)

Yes, Rohn 45G specs call for two brackets. For a 50' tower, upper at 36' and lower at 18'. For 80 MPH wind, this supports 25.9 sq. ft. of antenna area.  The top bracket will be about 26'. This would put the tower height at 25' above the top bracket and we will have < 8 sq. ft. of antenna. The wall is heavily reinforced and we will be putting steel plates on the back side of the wall supporting the brackets.


Thanks,                  
                  Kevin. 
------------------------------------------------------ 
Kevin Hemsley 
kev at ida.net 
NF7J  
  ----- Original Message ----- 
  From: K7LXC at aol.com 
  To: towertalk at contesting.com ; kev at ida.net 
  Sent: Thursday, June 15, 2006 10:20 AM
  Subject: Re: [TowerTalk] Bracketed 45G



  In a message dated 6/14/2006 3:50:27 P.M. Pacific Daylight Time,  
  towertalk-request at contesting.com writes:

  >  I am working on plans for a 50' bracketed Rohn 45 tower. In  going through 
  the Rohn catalog looking at foundation drawings for Rohn 45  bracketed 
  towers, you can either use a base plate or plant a tower section  in concrete 
  for the foundation. Is there a reason not to use one method or  the other? 
  This tower needs to be unguyed and will be bracketed to a brick  building for 
  a community installation. The county wind rating is 75MPH.  The antenna load 
  will be less than 8 sq feet. The top bracket will need to  be a little lower 
  than the Rohn specs. 45G was selected over 25G because  of this. Any 
  recommendations or caveats are  appreciated.


          My first question is what  heights it's going to be housebracketed at 
  and how much tower will be  above the top bracket (Rohn specs call for 2 
  brackets)? The Rohn specs allow 14  feet above the top bracket and will take 
  approximately 30 square feet at 75 MPH.  (Obviously you can go up a little higher 
  while de-rating the capacity.)
   
          In my experience, having  the bottom of the tower in the concrete is 
  much more stable than bolting a  baseplate to the concrete but since the 
  brackets will be taking the side forces,  it doesn't make much difference which way 
  you go. 
   
  Cheers,
  Steve    K7LXC
  TOWER TECH -
  Professional tower services for hams
  Cell: 206-890-4188
  _______________________________________________



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