clamps from gibsons all need to be replaced scrap yard batteries pipe ground rod 55g drums tractor supply W8JI Ham Member QRZ Page The difference between what Rohn says and what is likely to work is pretty large. This is because there has to be huge safety factor on things like the base. 25G, if you really have 25G, will support small antennas like a 2M antenna at 40-50 feet in some pretty strong winds without guying. I have 60 feet on my TV antenna and it has been up for years with no guys. This is beyond their ratings. I sure would not sweat 40 feet of it, because there are hundreds of thousands of TV towers 40 feet tall and they are a whole lot weaker than 25G. I agree with W8JI's comments. Back in the 1970's we installed Lots of Rohn 25G towers, Mostly what we called "50 footers" Which was 4 straight sections of tower, With the first section in a 3 foot cube of concrete, Plus a 9 foot "rocket" top section, For an actual above ground height of 46 feet, Plus the mast above the tower, So a television antenna was 50 feet above ground. ALL of those towers worked well, And the only ones not still standing were intentionally removed. (Rohn specs were for 40 feet above the highest support, So we were exceeding Rohn Specs by 6 feet) With one more tower section added, What we called the "60 foot tower" Some more maintenance is needed to keep it tight....... But none have ever come down over the years. The "70 foot" Rohn 25G tower NEEDS guy wires! At 70 feet freestanding, It will come down. (The tower itself will fail, Not the cubic yard of concrete base.) All of the above examples are of a "straight" tower section imbedded in the standard one cubic yard base. (Be sure to add gravel under and around the legs for drainage!) All concrete is poured against UNDISTURBED soil only. No below grade forms. None of the Rohn base plate units we worked with was very solid. IF you use some kind of tilt over base, DO have a house bracket, Or guy it. Remember your house bracket, Or guy lines will be doing all the "work" of holding it up. K9KJM Ham Member QRZ Page W6UV said: ? Did you climb these 60' free standing towers? YES, In fact I did. Way back in the 1970's. And they WERE shaky when new. I never enjoyed that. For many years now I have no longer climbed such towers freestanding. (I go up about halfway to two thirds of the way up and install temporary guy lines to work on them) But the fact remains that of many such towers around here, NONE have come down unless intentionally taken down. (All were also loaded lightly with a single medium to large size television antenna) A real testiment to Rohn overkill engineering! N5MDT Ham Member QRZ Page Isn't ham radio all about experimenting, modifying, and improving? The original poster is simply doing what hams have been doing for generations. Rohn puts out specs that it knows will work in all locations where the tower will be installed. With a few notes of course for special situations. And they build in a safety margin to protect themselves from liability in the event something unusual is in the terrain or construction materials, etc. Even when the Rohn specs call for one thing, if you simply cannot do it you may alter the installation to suit your particular needs. When you do, all you are doing is releasing Rohn from any liability for damage, and assuming all risks yourself. And, of course, your insurance company may not pay claims for damages if the install was not to manufacturer specs. Common sense helps and having an engineering background does too...but not all of us have those things... I installed a Rohn tower at my temp qth and did not follow the Rohn specs exactly. Put a much bigger antenna on the tower than is recommended, but made some alterations to the install. And, I have no problem climbing the tower. First, I would never use a surface mount ever, for a free standing tower. My tower extends through a 4 x 4 x 4 foot block of concrete poured into a hole dug in otherwise undistrubed soil, into a drainage bed. It is just over 40 feet tall with a Cushcraft A3S+40m add on kit. That is about 6+ sqft of wind load. Then another 20 mast with a 2m beam and a 2/440 omni on top of all that. WAY over specs. BUT, it is bracketed at the 20' level, AND the entire antenna 'array' is on a Hazer that can be lowered to the 20' level in the event the winds are expected to be sustained above 20mph or so. Normally the winds don't get to 70mph unless a hurricane is coming through. What's your average wind speed? 12-15mph? I have taken what I believe to be calculated risks and am willing to accept the consequences should it come down. I think that's what we all do every time we modify a circuit in any piece of ham radio equipment. The tower is only different because it has more severe consequences. What can I say? I live on the edge. N5YPJ QRZ Moderator QRZ Page I've climbed a couple of 25G 60 fters, didn't like the sway too much but it wasn't coming down. I was given a 70 fter a few years back that was missing a guy, I went up about 50 ft to attach the crane hook. I still can't remember why we wound up laying that one down instead of picking it up and tailing it out as the crane lowered it. The guy giving it to me was adamant about getting it down. I believe that Rohn rates the 25g free standing at 40 ft about 2 sq ft wind load and when you get down to 30 ft it's more like 6 sq ft or so. Personally were I putting anything larger that a large 2 meter yagi on a tower over 40 ft I would guy it. Nowadays I can't climb anymore so it's a moot point! KM1H Ham Member QRZ Page I got my tower training when our HS club had access to a 650' tower for field day. I climbed it and put the 2M ground plane on an unused hardline at the big top platform. Later in the Navy Id climb a mast and shinny out the yardarm in a storm to repair an antenna. Heights and movement never bothered me as long as I knew they were rated for what I was doing. The scary moments were free standing 60' Heights aluminum towers. The only time I ever chickened out was to swap a rotator under a TH-6. That thing was all over the place by the time I got to 50'. Someone else did the work and a few weeks later the tower came down in a storm. Carl KM1H Carl KM1H WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page K9FV said: ? Thanks for the pdf file - that's just what I was looking for. I'll save it for future reference. 73 de Ken H> That was the sheet I was referring to, which I have in a notebook at home. My recollection of 40' with just about zero load was correct. 30' is a safer bet. Personally I hate the way unguyed 25G "feels" when climbing it unguyed. I wouldn't climb one above about 20' without guys, they just get too shaky even when new with all very secure bolts. I'd trust one higher with an antenna on it, just not with me on it.:p KM1H Ham Member QRZ Page 36-46' free standing is rather common for 2way users with a VHF/UHF collinear on top and mouted on a flat roof. The ones I still service all got a level of 3/16" guying; some of the installations are scary. An old Navy buddy owns a local 2way sales and service shop but he refuses to climb so I still get exercise....keeps me young and virile:) I dont think Id climb 60' free standing. Carl KC2UGV Ham Member QRZ Page AI3V said: ? Hey Tommy, What happens when those "pretty strong winds" fold that improperly installed tower righ across your kid's bedroom? Rege If you read his post, he gives several scenario constraints (Below 40 ft, light antenna, etc). And, comparing to higher, weaker towers, that have not keeled over; it's a safe bet bet it wont happen. YMMV, however. I have installed over 85 Rohn 25G towers in the past 30 years. Many have been 40-50 foot with the proper base and no guy wires. These have been for the CB'ers and Ham radio operators. These also have anywhere between 3 & 6 element beams. Never have heard of a problem with any of these. I know of a 70 foot Rohn 25G tower that has a 4 element Moonraker beam with no guy wires. It has a 5'x5'x5' concrete base and still standing after 25 years of North Louisiana weather. Ok, back to reality. With good solid ground. Not sandy or marshy ground. And the proper hole dug 3'x3'x4' with a foot of gravel in the bottom and a 1"x6" form around the top. A few pieces of concrete wire wrapped between the tower and earth. This will be suffice for a 40 foot non-guyed tower. With a moderate beam. Been there done that. W5KGT Calhoun,La.