Wow, what a response. There were about 30 responses in less than one day. To summarize, I made a table, sorted by tower height, as to the specifications that were used to construct the anchor. Note how few of the concrete pours are >2 Cu.Yd., which by the way, are the some of the ones designed by a PE. Also, there was an excellent message by Arliss, W7XU, which has some excellent data from Dick, K5IU, a ME who does the Rotating Tower Systems thing. I attached the message in it's entirety below. Conclusions? There's a wide variety of installs, here. Some of them I would probably bet money that they wouldn't survive 80MPH winds. What I forgot to mention is that some of the below examples have gotten pulled out of plumb. Using the same calculations as for an antenna mast, a 4" x 0.25" wall pipe would snap off (bend) at the concrete in my installation if it stuck out of the concrete more than 3'!! (90' tower, 80MPH) And some are using it 6' or even 10' out of the ground! What am I going to do? Dunno. 6" pipe minimum, or W8x15 I-beam, 3-5 feet out of ground, and because of the large overturning/lever action, probably a deep hole, 5-6' deep. Also, like the Rohn standard anchors (4b and larger), I will probably make the concrete wider being "broadside" to the tower and rebar the width of the concrete. Thanks for all the messages! Chad Twr Ant Elevated Guy Post Anchor Data Hght Load Type Size Len In GndOut GndCu.Yds. Size Deep ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- Pipe 6" 10 4 6 4 HDBX I-beam 4" 11 4 7 T/O Pipe 4"x0.25 12 6 6 bell 7 60 Pipe 8"x0.375 10 3 7 0.11 1x1' 3 73 L I-beam 8" 5.5 3 2.5 1 3 75 Pipe 4" Sc40 10.5 4.5 6 0.17 1x1' 4.5 80 M Pipe 4" 6 3 3 0.09 1'dia 3 80 S I-beam 6" web 7.5 4 3.5 1.3 90 S Pipe 6" 8 3 5 0.75 3 90 I-beam 8 4 4 0.11 1'dia 4 93 S I-beam 4W-15 8 4 4 0.16 14"dia 4 100 L Pipe 6"x0.25 9 3 6 1 3.5 100 L I-beam 10W-24 11 6 5 2 3x3' 6 100 Pipe 5"x0.25 10 4 6 1 4 105 M Pipe 6" 8 3 5 0.75 3 120 L Pipe 4" 7 4 3 120 L Pipe 6" 12 6 6 2 3x3' 6 120 L Pipe 4"x0.25 7 4 3 1+ 4.5x? 4 130 I-beam 4" std 10 5 5 0.33 18" dia 5 130 I-beam 6" wide 10 5 5 1.5 5 130 Pipe 3"x0.25 8 5 3 0.06 8"dia 5 130 Pipe 5"x0.25 10 4 6 1 4 140 L I-beam 12" 9 5 4 3 4x4' 5 150 Pipe 7"x0.5 9+ 4 5 4.5 3.5x7 6 160 Pipe 8"x0.375 10 5 5 1.3 3' dia 5 192 Pipe 4" 13 3 10 HDBX is Rohn HDBX self-supporting tower T/O is a Tilt over tower Ant Load: S=small, M=medium, L=large Most measurements in feet. ------------------------ From: W7XU Arliss Reply-To: w7xu@dtgnet.com To: Chad Kurszewski WE9V Subject: Re: [TowerTalk] Elevated Guy Anchors Hi, The following information was from a talk K5IU (a mechanical engineer and owner of Rotating Tower Systems) gave at (I believe) the New Orleans DX convention a few years back: For posts 7-8 ft above ground: Installation Width and Ht. Length Small 2 ft 5 ft Med 3 9 Big 4 10 The above dimensions are for the concrete bunker. The post sits in the middle of the bunker. The top of the bunker is 1 ft below ground level. (Yes, that's right, almost 6 yards of concrete per anchor for a large installation). Post size: Round post, with guys attaching at 7-8 ft above ground Installation Post diameter Wall thickness Small 5" or larger 0.25" or more Med 7" or larger 0.38" or more Big 9" or larger 0.50" or more Wide flange I-beams, with guys at 7-8 ft above ground Installation Wide flange I-beam size, A36 steel Small W 6x12 (6" X 4" - 12 lbs/ft) Med W 8x15 (8" X 4" - 15 lbs/ft) Big W 10x33 (10" X 8" - 33 lbs/ft) What is a medium or big installation? I have a rotating Rohn 25 tower approximately 135 ft high. It has eight 17-el 2 meter antennas on it, stacked one above the other from 30 to 135 ft. The windload of each antenna is 2.7 sq. ft., plus phasing lines, etc. That qualifies as a medium size installation (per K5IU). I have another rotating tower, 140 ft high. Rohn 55. It's designed to hold a 10 ft dia. dish, a 6 ft. dia. dish, a 4 ft dia. dish, 8 long boom (~22 ft) yagis on 432, 4 long boom (~28 ft) yagis on 222, and a couple of vetical beams for 2m FM and 440 FM. That is a big installation. I have elevated guy posts for both of the above towers, and followed K5IU's guidelines for the concrete bunkers. I also did some reading on my own and discussed it with a friend who is a civil engineer -- it takes a lot of concrete and steel to make proper elevated guys. A friend of mine skimped when he put up what is probably a small system (a tribander and 2m beam on 70 ft of Rohn 25) and now his posts are pulled out of plumb. Hope that gives you some ideas. 73, Arliss W7XU