[bash]

Well, I've got 5 sections of 10ft and a top section approximately 9ft for my use. I'll probably just go with 40ft total, but my problem is getting it reassembled. I know it fits, because I just took it down, but it doesn't seem to line back up when doing a trial run with it laying down.


Does anyone have any secrets that they'd like to share about assembling or installing an antenna tower? I think what I'm using is similar to Rohn 20 except it has the tubular braces between each (3) uprights instead of the zig-zag bracing like Rohn uses.


Thanks in advance,

 

[SeanKelly]

How about some pictures? (Not that they'll help, but I just go ga-ga over antenna towers.)

 

[[email protected]]

Well Bash, what comes down, should go up.


Have you thought about how you will be erecting the tower? Section by section from the ground up? Or assembled on the ground and levered into place? With 40 or more feet of tower, assembling first and erecting second can be a HUGE task. My suggestion is to assemble one section at a time from the ground up. Again with that much tower, securing the first section in a concrete base is an excellent idea. With that done, you have a stable base from which to erect the sections one at a time, adding a few wall brackets as you go up (assuming this is not a free-standing tower installation). Using a gin-pole to hoist the sections into place is an easy process, and much safer than trying to pick them up above your head and align the tubes for insertion. You can fashion your own gin-pole with a 10' section of electrical conduit or EMT. Simply bolt a pulley onto one end and use vice-grips to hold it in place on the lower section.


As far as the dry fit on the ground, don't be alarmed if the individual sections don't match perfectly and slide together easily. There's too much variation from level over the length of the tower to allow that to happen. Call it "ground effect"...


Good Luck!

 

[BarryO]

Try finding a friend, or a friend of a friend, who is a ham radio operator. In other words. someone who has experience doing this type of thing to help you out. There are alot of ways to get seriously injured here.

 

[MAX HD]

bash,


The tower you have is probably a tubular bracketed model commonly used for tv antennas.Here's a site that has some good info....


Towers
http://www.tvantenna.com/products/tv...ng/towers.html


When I put up a bracketed tower two years ago I hired a guy with a bucket truck to lift the sections into place,while I worked on the tower,bolting the sections together.Even then I had to use a tapered punch,and wiggle the sections a bit, to align the bolt holes.Do not re-drill bolt holes.


Remember..SAFETY FIRST!

 

[Don Landis]

In my younger days I built towers up to 140 ft for ham and TV antennas.


The trick is in setting up the first 10 ft section and getting a stable base that will begin the tower plumb. Use a concrete base pouring with some galvanized pipe that will slip inside the three pipe sections. Make sure these pipes are at lease 2 ft long beyond the base. Bolt them on with holes drilled that match the tower holes. Now dig the hole for the base that you will pour the concrete into. Make sure the base is about 50% larger in area and at least 6 inches below the pipe sections you just inserted into the base. Attach the top section temporarily to the first base section. and attach some temporary guy wires (3 at 120 degrees apart) to the top section and attach a plumb line to the center thrust pipe where the rotator gets mounted. Now you should be ready to erect the first section. Use two 2x4 pieces of wood as a cross support to sit the tower om over the hole and fix the three guy wires to support the top section from falling over. The three pieces of pipe will extend into the hole you dug but not touch bottom. The bottom cross rungs of the tower will be suspended above where the concrete base will be when poured by the 2 2x4 supports that straddle the hole. Use more shims to suspend the base as necessary to make sure that the end of the 10ft base section where it joins the pipes is about 1 inch above where the surface of the concrete base will be. Now center the tower base. and adjust the 3 temp guywires so the tower is plumb using the plumb line that runs down the center of the tower from the top and fine tune the base slightly so the plumb bob is in the exact center of the triangle of the tower. IT is important that the tower be suspended over the empty base hole in a perfectly plumb placement and steady with the temp guys before proceding to pour the base. Using a level along side of the tower is not a good way to do this because it can never match the accuracy of the plumb bob in the center of the tower. Next pour the concrete base being careful to not move the base in the process and watching the suspended plumb bob to be sure. If you do move if just use a sledge habber on the base in a tapping motion to get it plumb and centered again before the concrete set up. Allow the concrete to set for 24 to 36 hours before proceeding. Once the concrete has hardened, remove the temp guywires and the top section. Replace with other sections one at a time until finished. With a steel tower you can probably do about 30 ft befgore attaching the first guywire permanent set. Then guy every 10 ft..

To position each 10 ft section I used a wood mast made from light weight spruce wood 2x3x 16 ft long. I had fabricated two steel metal straps that were U shapped that would slip over the towers top two cross pipes and had web strap that would fix the pole to the top tower section so far assembled. Mount a pulley to the top and use rope to make a flag pole like hoist to pull the tower sections up so you can guide them into place without using brute strength to lift the heavy steel sections over your head and try to slip them into place. With the hoist doing all the weight lifting and a good ground person working the rope you can easily guid the section over the top section and slip it on. Once mounted tap it down into place and line up the holes and bolt it. Now climb to the top, and attach a set of permanent guy wires. You may eyeball the alignment for tower straightness at this point but by adjusting the tension of each guywire with a turn buckle it should align easily. Now climb up and remove the hoist pole and attach to the next section and repeat the process.

If you ever need to remove the tower you can all the way down to the three pipes that are embedded into the concrete base.


Some towers have a prefabbed base plate that gets bolted into the concrete. This is a bit different and you pour the base first and then sit the prefabbed base kit on the concrete to template the holes where concrete screw anchors are drilled into the concrete. Once this is done there are leveling screws in this type of base that you adjust to plumb the tower using the previous procedure with the plumb bob as before. Most prefab bases will come with instructions that aid in mounting according to their particular design.

Safety-

Don't climb unless you are familiar with construction type procedures and have great respect for safety regarding working at lethal heights. Be physically fit for climbing work. Always wear a climbers belt with double attachment to the tower, one goes around the tower and the other safety lanyard clips on when you are in place. Never unattach both at the same time. Each should support your weight if you slip while the other is off. Wear construction boots to support your footing without fatigue or stress. Wear a hard hat and goggles. Getting whacked in the head or eyes at height is very serious compared to a similar injury on the ground. Be careful of power lines near by and do not plan a construction of a tower that may come in contact with these lines. In some communities it is a code violation to errect a tower that can fall over a power line.

 

[bash]

Don,


Great info!!!! I picked up several pointers from that. I and all others who plan to install a tower in the future are sure to benefit from that. Thanks again.

 

[RickRS]

I think you should also be using rebar to reinforce your concrete base. I suggest you look at this link for some more ideas: http://www.qsl.net/n1lo/towers.txt It the tower page from "Nylo's Notepad" a ham website.

 

[Don Landis]

That's a good reference site and offers more detail on some of the stuff I presented in brief. I was a bit surprised at some of the engineering overkill in parts there and if doing a small 40 - 50 ft tower a yard of concrete with rebar cage is just a bit over the top. I used to use a 20 " round hole about 24 inches deep in NY State, well below frost line, to erect 100 ft towers. These were guyed at 30 ft and every 10 ft up because they were Aluminum. On steel towers I would guy every 20 ft. The concrete base was adequate without rebar but I did use a 6 inch square wire cloth in a cylinder that the pipes were wire twisted to for support and strength. Some of those aluminum towers I built back in the early 70's are still standing. BTW- I have a 70 ft aluminum tower stored here in my back yard that I really should sell. Aluminum towers never age but they do not have the lateral strength that steel does. They also weigh far less and never rust ofcourse. Some of the newer galvanized towers last a long time too but back in the 70's nobody made a good galvanized tower, not even Rohn.

 

[RickRS]

What can I say, I'm an engineer Must must be in the genes, or something, that we get carried away at times.


Do keep in mind that I'm not a tower builder, have only one that I ever done. I'm not a mechnical or civil engineer (electrical) so I can't comment on the difference between rebar and re-enforcement mesh, but using the re-enforcement mesh would certainly add strength to your base over using nothing but concrete. The website's recommendations are similiar to Rohn's for their towers.