First, I would like to thank all that responded to my questions on installing a 40 to 50 ft. tower. You have been a very great help and I feel much more at ease with tackling the job. Hopefully when you purchased your new home you considered a tower installation. Unfortunately, when I bought 22 years ago, I wasn't into radio at all. Now I have to figure out how to fit one on a house/lot that was not laid out with towers in mind. Good luck... Here were my original questions: 1). I was planning on 40 to 50 feet of used 25g. Is there really any need to purchase a new base? Why couldn't you just use 3 to 5 feet of the first section if you follow the cementing recommendations in many of the previous posts? 2). I have heard that there are specs on the distance guys should be anchored from the base of the tower. I am assuming this is to guarantee some special angle at the guy/tower interface. If the required distance from the tower base is not possible but the "special angle" can be maintained, is that acceptable? ...ie: attach the quy wire to a 3 to 4 inch pipe cemented next to the fence line that is tall enough to maintain the guy angle. Rohn sez 80% of the tower height for the guy point distance. You can get by with a bit less if necessary. 3). Since the tower will only be 40 to 50 feet tall, would I be better served with a 2 el 3 band quad than with a triband yagi? I seem to remember reading that quads have a lower takeoff angle at lower heights than do yagi's at a comparable height, have less wind load and have more gain than a yagi with an equal number of elements. Here is a short summary of questions and the answers I received: Q. Can I bury part of the first section in lieu of purchasing a base? A. Seems like many already do this! (Unless they buy a new tower) Q. Can I elevate the guy points? A. Again, lots of folks do. Use strong risers. ie.."I" beams Q. Quad better than Yagi at lower heights? A. I think the jury is still out on this one. Some folks use and like the quad. Most say yagi's are more durable in snow, ice and high winds plus yagi's are easier to install and take down. I have not yet decided which I'll try as of yet. One well known contester listed the pros and cons of the yagi/quad controversy. I really did appreciate that. It was extremely informative. Finally, thank you Trey for providing an excellent resource for us new guys. Getting honest quick response to questions is very gratifying. 73 KC5DVT Wayne email...ehayes@vnet.ibm.com Austin, Texas ========================================================================= Subject: Re: Tower Installation Wayne- Here's some of my ideas... 1. Fine to go with 3-4 feet of the first section in the concrete. Just changes how much you leave behind when you move.... 2. The guying distance from the base has to do with the overall stress loading of the tower. The guy changes lateral wind forces into compression in the tower and tension in the guy. The angle determines the ratios of those forces as a function of lateral forces. To do the job right, you need a professional analysis. Maintaining the angle with elevated guy anchors (you 3 to 4 inch pipe) will maintain the forces the same on the guy and tower. But what about the forces on the pipe? Is it strong enough? Do you know? As always, there are two answers. The hard answer is that you should go hire an engineer. The easy answer is that with light loading, and a PROPERLY installed barcket system, you probably don't need any guys. 3. The analysis of quad performance at low height is somewhat of a bogus arguement, because if the two antennas are installed with the booms at the same height, the quad has active elements at a greater height than the yagi. If you would prefer a real world answer, I just put up a 2 element 3 band quad at 60 feet. It works about an S-unit better than a KT34XA at 40 feet; and about an S-unit worse than a KT34XA at 70 feet. Not bad, considering the difference in cost, hardware, and weight. GL! ========================================================================= > 1). I was planning on 40 to 50 feet of used 25g. Is there > really any need to purchase a new base? Why couldn't you just > use 3 to 5 feet of the first section if you follow the cementing > recommendations in many of the previous posts? Thats what I do for the base. Follow Rohn's drawing on installing the base. The drainage they show can be very important. The tower may transfer some vibrations to the house via the house bracket. This could cause some annoying sounds on windy nights. I think they make some rubber bushings that help reduce this effect. Perhaps they come with the house bracket?? > 2). I have heard that there are specs on the distance guys > should be anchored from the base of the tower. I am assuming this is > to guarantee some special angle at the guy/tower interface. > If the required distance from the tower base is not possible but > the "special angle" can be maintained, is that acceptable? > ...ie: attach the quy wire to a 3 to 4 inch pipe cemented next > to the fence line that is tall enough to maintain the guy angle. Rohn sez 80% of the tower height for the guy point distance. You can get by with a bit less if necessary. > 3). Since the tower will only be 40 to 50 feet tall, would I > be better served with a 2 el 3 band quad than with a triband > yagi? I seem to remember reading that quads have a lower > takeoff angle at lower heights than do yagi's at a comparable > height, have less wind load and have more gain than a yagi > with an equal number of elements. I doubt it makes much difference. A 2el quad will have abt the same gain as a 3el yagi, etc. Its generally easier to put up a bigger yagi. If you have ice loading problems I would go with a yagi. Keeping a quad in the air at QTHs with bad WX can be tough. > I do have a Rohn catalog on order which may answer some of these > questions but I also value real life experience from tower > users/installers. I case you haven't already figured it out Rohn's specs have a safety factor of about 5++ times built in. DISCLAIMER: Don't quote me on the line above! :-) ========================================================================= Subject: Re: Tower Installation ->I would like to install a tower on my city lot but have some ->questions that I have not seen addressed in the last couple ->of tower discussions nor can I find mention of them on KA9FOX's ->home page. Perhaps this knowledgable contest group can shed ->some light on my ?'s. The tower would be attached to the house ->at the eave peak which is about 15' from the ground. ->Ok, now the questions... ->1). I was planning on 40 to 50 feet of used 25g. Is there ->really any need to purchase a new base? Why couldn't you just ->use 3 to 5 feet of the first section if you follow the cementing ->recommendations in many of the previous posts? 40-50 feet of Rohn 25 with a house bracket does not require all that fancy of a base. This will be more than adequate... Get 10' length of 3/4 inch galvanized water pipe. Should run about $5-8 at Home Depot. This stuff will be 1 inch OD. Use galvanized steel .. not the black stuff. It should slide up inside a tower leg... perfect fit. Cut it into 3 equal lengths. aprox 3.3 feet each. Slide each length up inside of the tower legs of your bottom section about 6-8 inches. Mark were the tower mounting holes line up on the pipe. Remove the pipes, drill matching holes. Re-insert the pipes and bolt to the tower section with grade 5 bolts... just like you are bolting tower sections together.. Dig base hole 24 x 24 inches 36 inches deep. Fill bottom 6 inches with sand/gravel. Lift up this bottom section with the pipe extensions and set it into the hole so that the bottom of the tower section is even with ground level. Level and plum the section and pour concrete. You now have a base that as far a I can tell is every bit as good as the Rohn 3' base section or using the base plate for a fraction of the cost. This will work fine for 40-50' 25G with medium loading... and you can even climb it 2-3 sections without temporary. If you ever take the tower down, the only thing you "loose" is the 3 lengths of pipe in the concrete. ->2). I have heard that there are specs on the distance guys ->should be anchored from the base of the tower. I am assuming this is ->to guarantee some special angle at the guy/tower interface. ->If the required distance from the tower base is not possible but ->the "special angle" can be maintained, is that acceptable? ->...ie: attach the quy wire to a 3 to 4 inch pipe cemented next ->to the fence line that is tall enough to maintain the guy angle. Ideally, the angle that all guys for a given level make to the tower should be identical. Generally, this means one constant guy radius for all anchors. But, if the ground slopes, then the guy radius for each anchor should be adjusted to compensate. Likewise, a guy anchor can be elevated to produce the same angle. The further out you can get the anchors the better. ->3). Since the tower will only be 40 to 50 feet tall, would I ->be better served with a 2 el 3 band quad than with a triband ->yagi? I seem to remember reading that quads have a lower ->takeoff angle at lower heights than do yagi's at a comparable ->height, have less wind load and have more gain than a yagi ->with an equal number of elements. This is the general consensus.. but I had a TH6 @ 50' and it worked SUPER! ->I do have a Rohn catalog on order which may answer some of these ->questions but I also value real life experience from tower ->users/installers. Rohn tends to be SUPER SUPER SUPER conservative.. which is good.. but at the same time it can drive you nuts. You don't want to cut corners but it helps to know what is REALLY important and what isn't. ========================================================================= Wayne, Concrete-filled drill stem along a fence line is a very good anchor, provided that it is in the appropriate base. Are you going to house bracket as well? Where in Austin are you planting this tower? Feel free to gove me a call. ========================================================================= Wayne: I have an installation very similar to what you are describing. I started with 60ft of Rohn 25. It is bracketed to an eve at about 17 feet. The bottom 5 feet are set in the concrete base. I was careful to have the bottom sit in gravel so as to allow for drainage. To get the correct angles, I ended up guying it four ways instead of three. I only guyed it at the top. There is a ten foot mast with about 8 feet sticking out the top of the tower. Right above the top of the tower at the 55foot level is a KT34XA, and about 7 feet above it is a rotatable 40 meter dipole. Now, as to your specific questions: 1. I'll let the experts tell you whether to use tower as the base or not. I did and it worked out well. Guess the acid test will be to see how it has held up ten years down the road. It's been great for two years. 2. Many people use heavy pipe extensions to achieve the recommended angles as you have described. It works well as long as you use enough concrete to hold the pipe in place, and the pipe is heavy enough. 3. As to the choice of antennas, the answer isn't as easy. Until I put this tower up, I was a quad person. Probably more for economic reasons that anything else. If you are primarily interested in domestic contests, it shouldn't make a lot of difference. N6NB did an article in QST some years back comparing a two element quad with a three element yagi on various paths, and didn't see the great difference that everyone expected. Seems to me the heights he tested at were 40 and 90 feet. It's probably not entirely fair for me to compare performance of my KT34XA at 55ft with the 2 el quads I have had at 70 ft. There is not doubt in my mind that the XA has considerably gain than the quad did, and my current qth has a very good takeoff angle from north to south by way of east. I am really pleased with the performance of the KT34XA, so if I were to replace it with a quad, the quad would have to be 4 elements. At that, the maintenance of a two element quad left a bit to be desired, and a 4 element quad would be a whole lot worse. I guess given a choice between a KT34XA, TH7DXX, or C3, or a two element quad at 50 feet, I'd go with the tribander. My installation has been effective enough to win the CQWPX and ARRL DX contests in the low power categories for the US last year. Good luck, and enjoy the fruits of your efforts when you're done. See you in SS. ========================================================================= Hi Wayne, Just a quick comment: >...ie: attach the quy wire to a 3 to 4 inch pipe cemented next to the >fence line that is tall enough to maintain the guy angle. I did just that once, and it solved my problems of guying a 80 ft tower on a small city lot. I could even walk under the guywires! My pipe was some 5 inch I think. You need some calculations here. >Since the tower will only be 40 to 50 feet tall, would I be better >served with a 2 el 3 band quad than with a triband yagi? I seem to >remember reading that quads have a lower takeoff angle at lower >heights than do yagi's at a comparable height, have less wind load >and have more gain than a yagi with an equal number of elements. That is the general thinking of most amateurs, who look at a quad as a closed spaced stack. IMHO the radiation angle is only dependent on the height of the center of the antenna. Stacked beams does not pull down the radiation angle, but transfers power from higher loops to the lowest one. The lower loop from a stack is longer (bigger/fatter) than from the upper antenna alone, but its angle is higher than the lower loop from the upper antenna alone. The lower half of the lowest loop is almost unchanged stack or no stack. If your tower is not high enough, stacking or using a quad will not put more power out at low radiation angles. You may check with Terrain Analyzer 1.0 program from K6STI (advertised in QST July 95). One other point: quads are seldom mechanical stable. If you want low angle of radiation you need a higher tower (say 90 ft), unless your QTH is on a hill top. BTW, who says you need low angle of radiation? That depends on which contest you are in. Actually it would be nice to be able to control/steer the radiation angle. That is possible with stacked beams. For serious contesting you might as well move out of town right away due to TVI, noise level and room for rotating pole(s) and beverages. Easier said than done. =:-( ========================================================================= I use I beams that stick 4' out of the ground and 4' in hole filled with concrete. If your only going to put up a small antenna as indicated you should be fine. Several guys in Raleigh use the 4" pipe to elevate the guys. I did it to keep the guys clear of the ground because of the kids running around. As far as antenna I am using a Lightning Bolt 5 band quad. It works great. I have it mounted at 100' (90' tower, 10' mast). The price is right too, it was below $300. 73, ========================================================================= Subject: Re: Tower Installation >I would like to install a tower on my city lot but have some >questions that I have not seen addressed in the last couple >of tower discussions nor can I find mention of them on KA9FOX's >home page. Perhaps this knowledgable contest group can shed >some light on my ?'s. The tower would be attached to the house >at the eave peak which is about 15' from the ground. >Ok, now the questions... > >1). I was planning on 40 to 50 feet of used 25g. Is there >really any need to purchase a new base? Why couldn't you just >use 3 to 5 feet of the first section if you follow the cementing >recommendations in many of the previous posts? Not in my opinion, Wayne. I have used regular tower sections as bases many times with no problems. >2). I have heard that there are specs on the distance guys >should be anchored from the base of the tower. I am assuming this is >to guarantee some special angle at the guy/tower interface. >If the required distance from the tower base is not possible but >the "special angle" can be maintained, is that acceptable? >...ie: attach the quy wire to a 3 to 4 inch pipe cemented next >to the fence line that is tall enough to maintain the guy angle. The main thing is that you do not want the guys to get too steep. The rule of thumb that I use is "no steeper than 60 degrees with the ground." Rohn prefers them even flatter, like 45 degrees or so. Elevated guy posts seem to be a very desirable thing among lots of tower owners, mostly because it gets the guys above ground far enough so that you won't hang yourself on them when walking around in your yard at night or mowing the grass. I don't like elevated guy posts because it is so difficult to make certain they will stay vertical in a strong wind. A strong pull on an elevated guy post tends to pull it over which slacks the guy wire and then you have REAL trouble, like the tower may come down. If the pipe sticking out of the ground does not simply bend under the load, the concrete it is set in may rotate in the ground unless it is set very deep, like 4 feet or so, and even then it has to be a pretty good sized block. I would rather move the guy point down the tower a ways and leave the top 10 feet unguyed. >3). Since the tower will only be 40 to 50 feet tall, would I >be better served with a 2 el 3 band quad than with a triband >yagi? I seem to remember reading that quads have a lower >takeoff angle at lower heights than do yagi's at a comparable >height, have less wind load and have more gain than a yagi >with an equal number of elements. Wow, you have just opened up one of the raging controversies of ham radio. What is better, a quad or a Yagi? Maybe someone has finally modeled each of these with the currently available software and will share those results with you. I had a couple of quads 40 years ago and now I have only Yagis. This I know for certain: quads are MUCH harder to deal with when you are putting them up or taking them down since they are 3 dimensional as compared to Yagis which are 2 dimensional. >I do have a Rohn catalog on order which may answer some of these >questions but I also value real life experience from tower >users/installers. You may find as I have found that you won't get the detailed information you really need from Rohn. ========================================================================= Hi Wayne > really any need to purchase a new base? Why couldn't you just > use 3 to 5 feet of the first section if you follow the cementing > recommendations in many of the previous posts? I think burying the first section in concrete is what most people do. I used a 4' section that I cut off of an old tower at the base. I buried it in a yard of fiberglass reinforced concrete. There was a good 4" or better of pea gravel for drainage at the bottom. I also surrounded the tower with a rebar cage. The tower has been up at 40' unguyed and unbracketed for over 5 years with a small 3L Moseley tribander. It doesn't move, even with my 240 lb. body up there adjusting the rotor. I wouldn't trust a quad in Wisconsin weather. I have no other informed opinions on the age-old quad vs. yagi debate, but I think yagis LOOK a lot better. Too many CBers with quads, I guess...:-) Obviously I can't comment on guy issues, since I have none... Good luck & 73, ========================================================================= >1). I was planning on 40 to 50 feet of used 25g. Is there >really any need to purchase a new base? Why couldn't you just >use 3 to 5 feet of the first section if you follow the cementing >recommendations in many of the previous posts? > No need for a new base, except that you are ruining a good section that could be reused. Of course you can reuse it as a base again also. You only need 3 feet in concrete for your installation. >2). I have heard that there are specs on the distance guys >should be anchored from the base of the tower. I am assuming this is >to guarantee some special angle at the guy/tower interface. >If the required distance from the tower base is not possible but >the "special angle" can be maintained, is that acceptable? >...ie: attach the quy wire to a 3 to 4 inch pipe cemented next >to the fence line that is tall enough to maintain the guy angle. > What you suggest will work fine. In Colorado people often used well casing. You can also fill the pipe with concrete to make it even stronger if you're concerned. Be sure you have a good solid interface to the equalizer plate...like a bolt that goes through the pipe. You do not have a heavy duty application but better safe than sorry (especially since it's next to your house!) >3). Since the tower will only be 40 to 50 feet tall, would I >be better served with a 2 el 3 band quad than with a triband >yagi? I seem to remember reading that quads have a lower >takeoff angle at lower heights than do yagi's at a comparable >height, have less wind load and have more gain than a yagi >with an equal number of elements. > Am sure you'll get lots of comments on this but I would favor the quad if you don't have ice problems. Quads tend to require more maintenance (broken wires, etc) so talk to someone that knows about the best type of wire (maybe the new woven, flexible copper wire). If you go with a tribander, use the KLM KT34XA. 73, ========================================================================= Subject: Re: Tower Installation In a message dated 95-10-03 14:32:21 EDT, you write: > The tower would be attached to the house >at the eave peak which is about 15' from the ground. >Ok, now the questions... > >1). I was planning on 40 to 50 feet of used 25g. Is there >really any need to purchase a new base? Why couldn't you just >use 3 to 5 feet of the first section if you follow the cementing >recommendations in many of the previous posts? > THAT WILL WORK JUST FINE........ :) >2). I have heard that there are specs on the distance guys >should be anchored from the base of the tower. I am assuming this is >to guarantee some special angle at the guy/tower interface. >If the required distance from the tower base is not possible but >the "special angle" can be maintained, is that acceptable? >...ie: attach the quy wire to a 3 to 4 inch pipe cemented next >to the fence line that is tall enough to maintain the guy angle. > THEY RECOMMEND THAT THE GUY POINT DISTANCE BE A MINIMUM OF 80% OF THE HEIGHT... A _GOOD_ GUY BRACKET WILL SUPPORT 35 FEET OF TOWER ABOVE THE BRACKET WITHOUT GUYS... SINCE YOU ARE 50 FEET OVERALL I WOULD PUT THE GUYS WHERE THEY WILL FIT... IF YOU STLL FEEL YOU NEED AN ELEVATED GUY POINT TO GET AN ACCEPTABLE ANGLE, THEN USE I BEAM STEEL, NOT PIPE....CHECK THE SCRAP YARD... >3). Since the tower will only be 40 to 50 feet tall, would I >be better served with a 2 el 3 band quad than with a triband >yagi? I seem to remember reading that quads have a lower >takeoff angle at lower heights than do yagi's at a comparable >height, have less wind load and have more gain than a yagi >with an equal number of elements. > STICK WITH A YAGI AND SAVE YOURSELF A LOT OF HEADACHES...TRUST ME ON THIS WITHOUT A LENGTHY EXPLANATION - OR READ ON4UN'S OR G6XN'S BOOKS... >I do have a Rohn catalog on order which may answer some of these >questions but I also value real life experience from tower >users/installers. > >Thanks, > ========================================================================= Hi, Wayne. Here are my opinions: 1. You're right, you can put the tower right down into the concrete and that will be fine. Often an old bent-up section is used for this, as long as the part that comes out of the concrete is undamaged and it is installed in the concrete plumb. Rohn even sells 4' long sections for this purpose. Of course an undamaged 10' section is fine -- just imbed the bottom 3-4' in concrete. 2. 80% is the recommended guy anchor point distance from the base -- that is, 80% of the tower height. It's a matter of mechanical strength. Ideal would be guy wires that went straight outward, parallel to the ground -- they would have the maximum mechanical advantage. But since towers are generally ground mounted it is assumed that in almost all installations the guy wires go to anchors in the ground. The farther away from the tower they are, the more strength they will add to the tower. Many commercial installations use guying points considerably closer than 80% of the tower height, due to site limitations. They compensate for this by using larger gauge guy wire. Their engineers work it all up on paper to ensure that they end up with a tower and guy system sufficient for the wind load they will have up. They sometimes also use heavier tower, for this same reason. Many hams do as you say, imbed a steel I-beam in concrete in the ground to have a raised guy point. This not only makes the effective guying distance greater and can help you when your lot line is close, but also makes it easier to mow around. One of our locals, N3RR, just put in a nice tower using I-beam raised anchors. Another one that had them, until his station was taken down, was W4QAW. I think W7RM, a well-known multi-multi station, recently rebuilt in Washington State, has them also. 3. There has been much talk, for decades, about the fact and fiction of quads versus yagis. Having had both and having heard much of the discussion over many years, my belief is this: A. The quad's takeoff angle is the same as a yagi at the average height of that quad. Quads are three-dimensional; yagis are two dimensional (basically). Thus, a quad atop a 50' tower will be both lower and higher than a yagi atop that same tower. But the average height of the quad will be the same as the height of the yagi, 50'. Thus, quads do not have a lower takeoff angle; that is an old wive's tale. B. Quads are generally quieter in noisy conditions such as nearby manmade noise or rain or snow static, atmospheric noise, because the quad is a full-wavelength antenna, and a closed loop. I have observed this personally -- running Europe on large yagis, the noise level builds to the point where I can no longer hear the weak callers, but when I switch to the quad the noise virtually disappears and I can hear the weak ones again. Quite an impressive thing. C. There are serious mechanical tradeoffs in going to a quad versus a yagi, though. First, quads can be quite tricky to put up, take down, and maintain on a guyed tower -- becuase of their three dimensionality. Yagis are simple by comparison. Yagis are generally much more rugged mechanically and withstand the rigors of wind, snow, ice, bumping into nearby trees, etc. much better. D. I think it is generally accepted that a 2-element quad is roughly equivalent to a 3-element monoband yagi in performance. Likewise for multi-element quads, add one element to equate it to a yagi. E. Having a quad will give you much more of a conversation piece and you might well be the envy of your friends. F. Quads are lighter weight (hence more fragile) and can be rotated reliably with a smaller rotator. G. Most people would opt for a triband yagi as opposed to a quad. I'll be interested in what you decide and what other words of wisdom you get! 73 ========================================================================= Subject: Re: Tower Installation On Tue, 3 Oct 95 13:29:25 CDT, ehayes@VNET.IBM.COM wrote: > 2). I have heard that there are specs on the distance guys > should be anchored from the base of the tower. Guys should land out 80 percent of the distance up. [Fifty foot tower, plant guys 40 feet out.] > ...ie: attach the quy wire to a 3 to 4 inch pipe cemented next > to the fence line that is tall enough to maintain the guy angle. Instead of pipe with cement in it, get some structural I- beam from a job site. MUCH stronger. ========================================================================= 73's Wayne KC5DVT ehayes@vnet.ibm.com