Just got a tower..what next?

[AronDouglas]

Someone was about to throw away a 40 foot antenna tower ( new homeowner didn't want the thing on his property). Thankfully I was close by to take the thing off his hands I have the base plate, 3 tower sections and the top antenna mount.

What are the requirements on mounting this thing? Do I need guy wires if I set it in concrete? And how high can I legally go? I have a 16 foot fiberglass flagpole that I want to put on top of the tower to get just a little taller.

I am doing my own research on the side, I just want your opinions as well.

 

[prcguy]

Find out the make/model then see if its free standing or guyed. The mfr can supply you with engineering data for the concrete base or guying requirements.

40ft is not that high and if its a guyed tower you might be able to use a modest concrete base and house bracket if the antenna wind load is minimal but without the mfr info its hard to plan anything.
prcguy

Someone was about to throw away a 40 foot antenna tower ( new homeowner didn't want the thing on his property). Thankfully I was close by to take the thing off his hands I have the base plate, 3 tower sections and the top antenna mount.

What are the requirements on mounting this thing? Do I need guy wires if I set it in concrete? And how high can I legally go? I have a 16 foot fiberglass flagpole that I want to put on top of the tower to get just a little taller.

I am doing my own research on the side, I just want your opinions as well.

 

[mmckenna]

Check with the local agency that does building permits. Some locations (not all) require permitting and inspections for the physical construction work.

I'd also get someone knowledgeable in towers to take a look at it before you put any work into this. I got a "free" tower once and once it was taken down and I got a close look at it, I found a lot of issues with it. Plugged weep holes in various places had caused a lot of corrosion on the inside. Closer inspection found various pin holes where the corrosion had eroded enough metal. I ended up giving it away to another person who was able to use some of the parts and sections that were not damaged.

Just be careful.

 

[AronDouglas]

It looks to be in fairly good condition. Some minor surface rust here and there. It looks like the previous owner had painted it at least once. All weld joints are fine and as far as I can tell, the inside looks okay and rust free.

I think the guy had it setting on his concrete porch (hence the base plate). There are a few eye bolts about 3/4 of the way up the tower, so I'm guessing he did use guy wires. My personal opinion, I would not use wires if I set it concrete. I climbed up the base section (10 foot) and it was very solid. Its built with 1" tubing (think its 1"). I have no information on it whatsoever and I dont know how to get in contact with the previous owner.

This is what I have. American Tower Amerite 25 AME25 40 Foot Commercial Tower with Fixed 3-Prong Base Section (40-AME25-BT) from Solid Signal

 

[mmckenna]

Unlikely you'd want to do self supporting with that type of base. Looking at the specs for the Rohn 25, a very similar antenna, it does specifically say that self supporting is not to be done with the flat bases like that. Even then, they sell the 40 foot towers with guy wires at 38 feet. A tower that small and with that type of base is not going to be stable with just the flat plate mounting on a concrete porch. You are either going to need to bracket it to your house up fairly high, or guy it.

 

[AronDouglas]

I've seen people setting 3 mounting poles into 3 feet of concrete as a base, thats what I plan on doing. I know I'll have to secure the base fairly well, but I was more concerned about the tower itself. Are guy wires meant to keep the tower from bending in the middle or from falling over at the base? If the connection point between the tower pieces is stong enough (they done need wires), then I'll concentrate all my efforts on a good base.

The tower, as of right now, will be set up next to our barn. So that will act as a structural support if need be.

 

[mmckenna]

You really need to consult with the manufacturer. The towers are designed to be installed a certain way. Not following that design can be catastrophic. Installing a tower incorrectly and then having it come down on your house, your car, a neighbors property, etc will not go well. Your homeowners insurance will start looking for ways out of paying, and they'll be specifically looking at the tower installation. I'd really, strongly, encourage you to get some assistance with this. I've got one Rohn 25 at work and used to have another one. Both 40 feet and both guyed. Both supported VHF Super Station Master antennas, about 20 feet tall. Even with the guying, they'd move a bit in the wind. Also, even being "officially" certified as a tower climber, there is no way I'd climb those things.

Free is good, and it sounds like you may have got a good tower, but this is quickly moving into the area where professional help is required. Every year people are killed working on towers, even guys that are trained and do it professionally. I'd hate to see you hurt, killed or damage to your home.

 

[n5ims]

I've seen people setting 3 mounting poles into 3 feet of concrete as a base, thats what I plan on doing. I know I'll have to secure the base fairly well, but I was more concerned about the tower itself. Are guy wires meant to keep the tower from bending in the middle or from falling over at the base? If the connection point between the tower pieces is stong enough (they done need wires), then I'll concentrate all my efforts on a good base.

The tower, as of right now, will be set up next to our barn. So that will act as a structural support if need be.

Please note that this isn't an engineering answer but a simplified one for others to better understand what guy wires do.

Guy wires have several important jobs. First, they apply downward pressure to keep the tower in place. Second, they keep the tower from moving around in the wind. Third, they help guide the tower down into a controlled area should it collapse.

That downward pressure is like a broom handle being held vertical. If you're very good, you can have it stay vertical for a short while just sitting on it's base, but any wind and over it'll go. If you press it into the ground a bit (think a couple of inches here so it'll scale with the height of a tower) and it'll remain for much longer and with a bit more wind. The greater percentage that handle is in the ground vs. that in the air, the more forces it'll remain without falling. This is basically the principle of an unguyed tower. Now if you hold that handle from the top (or near it anyway) it'll remain for nearly as long as you can hold on. This is like a guyed tower.

The guys keeping the tower from moving is a bit more difficult to understand. For a short tower, pretty much all the force (think of the wind here) is from a single direction. Taller towers may have wind from one direction at the base and another near the top. More likely, though, is that the wind may be stronger at one altitude and weaker at another. Similar principle although the forces are a bit less.

That last point above is when things go really bad. Most folks would guess that when a tower falls, it simply falls down where a 1000' tower's top would be 1000' from the base. A good guy design helps to control this fall so the tower will break up into smaller pieces and keep them in a fairly small area of damage (so the nearby house owner doesn't have as bad of a day as the tower owner). This does generally require a tall tower and many guy wires to accomplish so it isn't as big of a worry for most of our towers.

That flat pronged base you have is a fairly weak base design. Don't get me wrong, it generally works fine if properly installed for a short tower holding small antennas. Don't skimp on the concrete pad (6" minimum and thicker is much better!) and the anchor bolts should be strong and correctly installed (best would be to use threaded mounting rods designed for the job placed along with the rebar prior to pouring the concrete). Often a section of the tower is imbedded into a large cube of concrete as the base (think 3' by 3' by 3' minimum) and don't forget to allow for drainage!. This can be a full 10' section but many tower makers sell a short base section designed for this.

Often you can get a "house bracket" that's designed to be securely mounted to a structure (like your barn) and to the tower to help support the tower. For short lightly loaded towers that's often enough. The higher it is placed onto the building, the more support it gives but it must be placed on something strong!

 

[AronDouglas]

I understand what you are telling me mmckenna, I will do more research on what kind of tower I have and what its specifications are. I've worked with a general contractor for nearly 12 years, and one of the jobs I've done is tree topping (it was for freinds mostly). I am not in any a professional, but I do have all the safety gear and some experance. I have assisted in topping two, 100 foot trees before. And believe me, I would not have even considered the job if I hadn't had all the proper gear.

As far as code/FCC regulations, I'm still trying to find out how high I can go in my area. I am outside city limits and I am not in any sort of residential area. So the 200+ acre wooded area around me wouldn't mind IF a tower fell on it Homeowners insurance is an whole difference can of worms that should be addressed in another thread. But if someone is addressing setting up a tower, typically its understood that they have considered homeowners insurance and other like topics. I do appreciate your concern mmeckenna, not very many people do these days.

The physics behind towers and guy wires can be extensive, and I'm starting to learn how big a project this may turn out to be I'm not intimidated by the work or the technical aspect/physics, its just getting the right information. Since I have NO information on this tower, I have to rely on pictures and design. I'll try to get some pictures uploaded some day, but the link I posted is pretty darn close to what I have if not exactly what I have. There are not any tower professionals (HAM operators) in my area, and I am certainly not doing to spend an arm and a leg for a tower specialist to come out and be irritated that hes inspecting a little 40 footer.

As far as antennas go, a CB base antenna and a good wide band scanner antenna is all that will be on it. I really want to get a Hy-Gain SPT-500 Super Penetrator, but worst case is I'll just have a 108" whip instead. And the scanner antenna is yet to be decided on.

 

[mmckenna]

So, for amateur radio and scanners, antenna height doesn't really matter in the eyes of the FCC. The agency that really gets involved here is the FAA. Depending on how close you are to an airport will dictate how tall your tower can be, but in all honesty, unless you are within spitting distance of an airport, a tower 40 feet tall isn't going to be an issue.

Local building codes might play in, so it would be good to at least call your county building inspector and find out if they have specific rules.

If you have any neighbors close by, best consult them. I can tell you that when a neighbor sees an antenna, it and you will get blamed for every single piece of electronic equipment that ever breaks down, poor cell phone coverage, fuzzy TV reception, warts, hernia, receding hair line, etc. If you've got enough land around you, this won't be much of an issue, but neighbors can still get annoyed.

Getting a scanner antenna up 40 feet should be a big help, but make sure you consider getting some good coaxial cable. Same with your CB. Good cable makes a huge difference.

Don't forget to ground the bee-gee-burrs out of it. Lighting and towers go together light peanut butter and jelly.

 

[KSDeputy]

When we built our home, 27 years ago, I had a Rohn 40' tower put up and the concrete base tied to the foundation of the house. It has not moved. I have a lightning rod on the top, I have scanner antennas on two standoffs, plus a weather station. One antenna is for the weather radio as it gets much better reception with an outside antenna. In my younger days, I climbed as high as 25' many times. I have a climbing belt. I put two dusk to dawn lights on the tower. It has three TV antennas on it, so we can pick up stations from the east and west without having to turn one antenna. Since the advent of digital TV, we pick up almost 40 stations & substations.