How much antenna mast is safe?

[MB]

Anyone have any idea about how many 10ft. (1.25inch) antenna mast sections you can put together before it becomes unstable or unsafe? I have a 107" antenna that weights 8lbs and has a 125mph wind survival rating. Currently I have it mounted with 12inch wall mounts at 25ft. I am thinking about adding another 10ft section. I have had this 25' section for a while now and it has survived many wind storms. Do you think I will be OK at 35ft?


This is the Radioshack mast I have been using:

Mighty Mast
This mast is great for your heavy-duty jobs. Built with sturdy construction, the 10-foot, 16-gauge steel with its 1¼" diameter is ideal for satellites systems. The gray color matches most DSS satellite systems and blends well with most roofs.

• 16-guage steel; 1¼" diameter
• Sturdy construction
• Gray color matches most DSS satellite systems and blends well with most roofs

 

[buttsrob]

I have had this 25' section for a while now and it has survived many wind storms. Do you think I will be OK at 35ft?

If you're talking about adding another 10 ft without support - I wouldn't risk it. You could probably add guy wires near the top however. I'd just attach them with a hose clamp. That would insure you can stand the same wind load.

 

[MB]

How many guy wires should I use and where should I mount them on the other end?

How would I mount the wires to the hose clamp?

I have no experience with guy wires. Help!!

 

[VernM]

For 35 feet of TV mast, you want to guy it at the half-way point as well as at the top. Radio Shack has the attachment hardware. It it a metal circle with holes for guy wires. It slips down the mast and locks with a hose clamp.

Guys should go out around a 45-degree angle (at least the lower ones) and be secured to sturdy anchors that are either driven 3-feet into the ground or some sort of equivalent sturdiness. For scanner frequencies, you can get by without breaking the guy wires with insulators (to reduce RF resonance problems) but do look at the ARRL guy wire info or some other reliable source to be sure you have done it right. Then sit back and wait, as we hams do,for the wind storm that will bring it down "If your antenna didn't come down in the last big wind storm, it wasn't up high enough." is the ham's mantra.

 

[ReceiverBeaver]

Hi MB, there are guy wire kits available at places where you can obtain antenna hardware. RS should have them although I don't have a catalog number for you.

Yeah you're gonna need need guy wires to go up any higher.

Typical arrangement is 3 wires, spaced out at 120 degree equal spacing increments (triangular). Probably need to locate the mast-guy connection about 3/4's of the way towards the top.

A manufactured mast guy ring is a circular piece of metal with a 1 & 1/4" hole in the middle so it fits around standard mast pipe. Then it has smaller holes drilled in it for attaching the guy wires. You may have to drill a hole through the mast pipe and insert a bolt or something. This will keep the ring in place and keep it from sliding down the mast below the point where you need to locate it.

You do not have to use wire. Smaller gauge rope will do but you should use only Dacron. Dacron is what you see hams using to support their wire antennas. Dacron is the only synthetic cord that is impervious to UV rays from the sun meaning the sun will not rot it over time. Your installation will be more or less permanent. Cotton rope will rot from getting wet & the sun ect....Nylon ski rope will experience UV sun rotting and break down. Dacron is widely available at ham stores, ham coax & wire supplies like The Wireman ect... and on Ebay. It doesn't cost that much.

If you choose wire, use a stranded galanized wire that won't rust.

The "ground end" of the wires typically connect to points on your roof. If your antenna is installed in the middle of your roof then this shouldn't be a problem. If it's on one end of your house, then 2 of the points can come back to your roof but the third will have to go off to a tree or down to the ground.

Roof achor points are usually a threaded "hook" or "eye" screw, a nice heavy duty one at least 4 inches long. They have wood-type threads on them and you make a little starter hole in the roof with a large nail or scratch awl, and them screw them in. A long screwdriver makes a good cheater bar to finish screwing the down as it gets tight.Or you can use a pair of pliers. You shouldn't be able to screw it all the way down by hand. If there's something else on your roof you can use as a tie off point like a chimney...use it....just stay with the ballanced 120 degree layout pattern.

If your 3rd guy can't go to a tree and must come down to the ground, then you'll need a bigger, heavier duty anchor rod of some sort to pound into the ground that will stay in place over time.

To adjust and tighten the ropes/wires, you can make or acquire simple tension adjusters like you might see supplied with camping gear to take up the slack and adjust tarp guys ect..I've seen these homemade out of a small piece of wood with 2 holes drilled in it. Or the proper hardware device is called a turnbuckle. This is a simple doublesided adjustable screw gizmo.

Turnbuckles and the Eye Screws mentioned above are both very common. Any hardware store will have them as well as Big Orange or Lowe's ect....

I hope none of this sounds too complicated or like too much trouble. Guying is what you have to do when you've got too much mast (thereby weight) up in the air to be self supporting. The only other alternative is to watch your antenna system crash and burn with the next gust of wind.

good luck buddy

 

[Hoofy]

MB, how is your current mast set up? Does it run from the ground up near your house or is it free standing. You might be able to add the extra 10 feet without guy wires if you can attach it to a structure or if your current mast is supported near the 25 foot mark.

 

[fuzzymoto]

Just curious. What antenna are you using that will survive 125MPH winds?

 

[Skypilot007]

I currently have an 17ft mast pole (galvinized fence pole) straped to my chimney with a 24ft 10 meter verticle on top of it. No guys, no problems.

 

[MB]

Thanks for all the help guys! Some good information here..

My current mast setup is free standing. About 5.5ft of mast is held to the side of my one story house with a 12" wall mount (which is actually 2 pieces). The rest of the mast sticks above the roof edge about 20 ft. Then the 9ft, 8lb antenna above that. I have had this setup for a while now. It has been through some pretty good wind storms.

For my new setup, I plan on adding another 15ft of mast making the total 40ft. For this setup I will also make sure the mast goes all the way to the ground and I will use two sets of 12" wall mounts. With this setup there should be about 11ft bolted to the side of the house in 4 spots and touching the ground. There will be about 29 ft of mast above the edge of the roof line.

So the new setup will actually be about 9 - 10ft taller then the last setup. The new setup will also have an extra 12" wall mount with the top most mount right near the edge of the roof line. The weight of the new setup will also be resting on a concrete block on the ground as opposed to free standing.

So, I am wondering since my original setup was pretty sturdy and held up to some pretty strong winds, and this setup is only about 10ft taller including some extra reinforcement. Could I get away with just one guy point on the mast? Do you think if I guy the mast at about 20 - 25ft above the roof line I would be ok? I would hate to have 6 guy wires runnig all over. Maybe if I use 4 wires at the 25ft (above roof line) mark. I would place all the wires 90 degrees from each other.

How does this sound?

Or, should I opt for two seperate guy points with 3 wires at each point?

What does everyone think?

MB, how is your current mast set up? Does it run from the ground up near your house or is it free standing. You might be able to add the extra 10 feet without guy wires if you can attach it to a structure or if your current mast is supported near the 25 foot mark.

 

[MB]

Just curious. What antenna are you using that will survive 125MPH winds?

I am using this antenna:

http://www.antenex.com/c_search.asp?txtFunction=browse2&selFamily=FIO&txtSubFamily=VHF+3+dB+GAIN+MODELS

http://www.antenex.com/c_search.asp?txtFunction=browse1&selFamily=FIO&selMarket=.&selApplication=...

It is an Antenex FG1523 3dB VHF-Hi Fiberglass Omnidirectional antenna. It weights about 8lbs and is 107" long. The specs that came with it show a 125mph wind rating. This has been an awesome antenna! I am picking up signals I never dreamed about receiveing. I got a really good buy on a brand new one - I paid around $120 for it, which is about $150 less then retail.

However, I am always looking for something better! I live in a very rural area with a lot of mountains and valleys, so I need a good high gain antenna. 98% of my listening is VHF-Hi. I asked this question in a different thread - but I am looking for a higher gain antenna that will allow me to receive even more. Anyone have any sugestions?

How much more would I gain with a 6dB antenna at the same height as this 3dB one?

 

[MB]

I currently have an 17ft mast pole (galvinized fence pole) straped to my chimney with a 24ft 10 meter verticle on top of it. No guys, no problems.

I wonder how the fence pole compares to the antenna mast I am using strength wise? What is the dia. and what guage is it?

Your setup is a total of 41ft as compared to mine which is 49ft. You must be about 35ft above the top of the chimney while I am going to be about 38ft above the roof line (antenna included). So maybe I will be OK with just one guy point.

What would you suggest?

 

[RISC777]

$0.02 Input

I've got two masts up. One is 35' and the other is about 45'.

The winds I deal with 90 percent of the time run west to east, so the shorter has two guys to offset that wind load (1 pound discone, no real wind load to speak of.) The taller is a telescoping mast which came with rings to attach guys to.

On both I use 1/8" 'wire rope.' Thimbled and clamped at the top/mast end, thimbled to a hook/eye turnbuckle at the roof end. Flat plates with rings for the turnbuckles to hook to. All stainless steel.

The tallest is guyed three ways, not every 90 degrees. It also has a light antenna with no real win load. Oh, and a yagi's on that mast also. Two LMR-400 runs and their weight on that heavier mast of the two.

Both antennas rated at 100 mph, one might be rated for 125. Gusts can approach 60, very ocassionally higher. No issues. Just tied strapped the feedline cables to the masts, weather proofed the cable connects.

Three guy lines works for me, though I won't argue or dispute four might be better in other installs, locals.

 

[MB]

When you say the shorther has two guys, do you mean two guy points or two guy wires?

How many guy points does the tallest one have? I think I understand what you mean when you say "the tallest is guyed three ways" - the tallest has 3 wires about 120 degrees apart - correct?

I am a little confused here, from your post It sounds like the shorter mast is guyed in one spot with two wires and the tallest is guyed in one spot with three wires. Am I correct?

Also, how are both masts mounted to your house?

 

[Hoofy]

I think 3 guy wires would work fine. For everything above the roofline I would use antenna mast because it is usually stronger and lighter. For the mast below the roof you could get by with conduit or even pipe. If the mast above the roof is going to be multiple sections of mast you might want to use a couple of guy positions. Put one near the top and another about half way to the roof line.

If you're going to have it setting on concrete you could build a hinged base (similar to a tilt down flag pole) and then walk the mast up and fasten it to the house. I don't think you would need to add additional stand-offs from the house. With it standing on the concrete the 2 you have on the house should be plenty. I've helped do this several times and it works well.

I don't use wire ties to fasten coax to a mast or tower any more. I use plastic electrical tape because I have seen where the wire ties have cut into the outer coating on the coax.

Consider using UV safe rope for your guy lines it's available lots of places now.

Your question about raising your current antenna verses a higher gain antenna at the same height. I think that only experimenting will give you the answer. There are too many unknowns. You may not see any better reception by raising your current antenna, but you might see a significant improvement. If you have some signals coming in that are marginal then raising it may really improve it. If youre looking for signals that you don't hear now then you may be disapointed. Hills and structures can cause shadows in RF signals as well as transmitting antennas do have nulls. There's no way to tell if you're in a shadow without experimenting.

Take all the info and suggestions that you get and sort out what will work the best for your situation.

Good luck.

 

[MB]

Thanks for the help Hoofy!

I think 3 guy wires would work fine. For everything above the roofline I would use antenna mast because it is usually stronger and lighter. For the mast below the roof you could get by with conduit or even pipe. If the mast above the roof is going to be multiple sections of mast you might want to use a couple of guy positions. Put one near the top and another about half way to the roof line.

I am going to add the new mast tomorrow, and make a decision if I will use one or two guy positions depending on how sturdy it feels.

If you're going to have it setting on concrete you could build a hinged base (similar to a tilt down flag pole) and then walk the mast up and fasten it to the house. I don't think you would need to add additional stand-offs from the house. With it standing on the concrete the 2 you have on the house should be plenty. I've helped do this several times and it works well.

How would I construct a hinged base? With a 40ft mast, I am not sure I would have room to lower it because I have a tree line that is about 30ft behind the mast and other structures nearby. I will have to look into this however..

I know I am really going to have a tough time wrestling around with the 40ft. mast and antenna, the 25ft mast was hard enough! Good thing I have someone to help me.

Do you know if there is any easy way to seperate mast when it is allready locked together? Maybe a sledge hammer and large punch??

I don't use wire ties to fasten coax to a mast or tower any more. I use plastic electrical tape because I have seen where the wire ties have cut into the outer coating on the coax.

I have thought about that before. I used tie wraps on the mast we are talking about. I will change them over to tape when I am working on it tomorrow.

Consider using UV safe rope for your guy lines it's available lots of places now.

I have allready purchased galvanized steel guy wire.

Your question about raising your current antenna verses a higher gain antenna at the same height. I think that only experimenting will give you the answer. There are too many unknowns. You may not see any better reception by raising your current antenna, but you might see a significant improvement. If you have some signals coming in that are marginal then raising it may really improve it. If youre looking for signals that you don't hear now then you may be disapointed. Hills and structures can cause shadows in RF signals as well as transmitting antennas do have nulls. There's no way to tell if you're in a shadow without experimenting.

I guess your right, there are to many unknowns and variables. I will just have to try it and see what happens.

 

[kb2vxa]

Hi MB and all,

Let's put an end to this with the correct answer, please? 10' won't buy you anything so don't bother unless you want to reconfigure the mounting and perhaps the location and go the limit.

I once put up 50' of that Rat Shack mast on a tripod and three sets of three point guys, moments after making a mad dash down the ladder IT happened. The sky darkened, the wind howled and I was stung by what amounted to a Jersey Shore sand storm as I dove into the only shelter close enough, my car. When it was over the mast, monster TV antenna and rotor were still there and the kids in the day room were watching cartoons.

"You could probably add guy wires near the top however. I'd just attach them with a hose clamp."

Yeah, the hose clamp rips away or cuts the guy, either way CRASH. You can use a hose clamp to support a guy ring though but somebody already said that. Don't forget to guy the center, that's where it could buckle if guyed only at the top. You may reconsider that sort of mounting like I said, not only do you have the weight but the downward pull of the guys to consider as well. Wall brackets don't handle much downward force and lag bolts easily pull out unless they're deep into studs, wall anchors can rip the siding right off.

 

[Hoofy]

""Let's put an end to this with the correct answer, please?""

The correct answer is : You don't know that 10 feet won't make a difference.
I have seen many times when 10 feet or less took an antenna out of a null area and put it in the clear.

This guy wants to experiment and has already been told that it may have little or no effect but on the other hand it could make a significant difference. He's looking for some ideas on how to do things not just negative opinions.

OPINION: A conclusion or judgement held with confidence, but falling short of positive knowledge or evidence.

Ok, MB I have found that if I put enough sections of mast together to reach the roof and then go on the roof and continue to add sections while having someone hold the bottom of the mast out away from the house works fairly well. So when you get to the point where the antenna attaches you slowly stand the mast up and have the other person control the bottom of the mast on the ground and walk it toward the concrete pad or anchor point for the base. In this way you will be lifting a little bit at a time and you can attach guy wire positions and tape your coax as you go.

Good luck.

 

[MB]

Well I tried it. I had a really hard time getting the mast up, it took three people. Once I had it up it looked really unstable. Almost like it would buckle at any second. It was so unstable that it looked like the guys would have not even helped. So, I ended up taking the whole thing down and returning it to the way it was originally. So I guess I wasted some money on mast and guy material and wasted a good portion of the day.

Well, I guess you never know until you try!

I am looking for a good 40' tower. Any opinions??

 

[W4KRR]

Well I tried it. I had a really hard time getting the mast up, it took three people. Once I had it up it looked really unstable. Almost like it would buckle at any second. It was so unstable that it looked like the guys would have not even helped. So, I ended up taking the whole thing down and returning it to the way it was originally. So I guess I wasted some money on mast and guy material and wasted a good portion of the day.

Well, I guess you never know until you try!

I am looking for a good 40' tower. Any opinions??

Years ago I had a 40' Rohn tower. It was made up of four of their "25G" ten foot stack sections. I had it on a hinged base so it could be folded over for maintenance, hurricanes, or whatever. It had a single house bracket around 8 feet or so off the ground, and no guy wires. It was up for over 20 years, and I never had any problems. Keep in mind that this arrangement will require a concrete base roughly three by three by three feet deep, i.e., one cubic yard of concrete. Also, if it's on a hinged base, you will need a minimum of three people to "walk it" up or down safely. I actually constructed a winch and pulley arrangement so that I could do it by myself if necessary, but it's still safer with more people, and I don't recommend doing it by yourself.

Now, if you don't want any guy wires or house brackets, try the Rohn BX series. These are free standing towers, and can be had in heights of 32, 40, 48, and 56 feet. I have never owned one, but they should work fine for VHF/UHF scanner antennas. Here is one source for the BX series. Or, do a Google search for "Rohn Towers", or Rohn BX series towers". Good luck!

 

[Hoofy]

Sorry to hear that it didn't work out for you. Too bad you didn't go ahead and hook up the guy wires. It would have made a big difference

We put up a 40 foot mast with an 18ft antenna on top of it. It took 4 of us to walk it up and it was like a noodle until we got the guys connected. It has withstood many blizzards.

As for a hinge system we used a couple of 2 inch pipes driven into the ground about 3 feet with a foot sticking above ground. We drilled a 1/2inch hole about 4 inches down from the top of each pipe and lined up the holes so that we could put a long bolt through both pipes and through a hole in the bottom mast section. Then we walked it up while one person used a rope over a high point on the house to help keep the flexing of the mast to a minimum. Once vertical we connected the upper support to the house while we attached the guy lines.

Good luck on your next try.