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[VE7RF]

Aluminum towers are available, BUT they all use 40 ksi yield strength material, like 6061-T6 etc.  They also use large diam
legs, and thick walled...and ditto with cross bracing..which is heliarc welded.   Modulus of elasticity of aluminum is triple that of steel. Aluminum will flex 3 x times as much, and also twist 3 x times as much..as steel.   It's not an ideal material to build towers from.  Aluminum is a little more than 1 /3 the weight of steel. (2.76" thick alum = 1" thick of steel).   To get some strength from the aluminum structure, it ends up using bigger diam legs, thicker legs, thicker and bigger cross bracing, more cross bracing etc.  Add all that up, and the weight savings rapidly vanishes.  Alum has skyrocketed in price too. Alum is best used for ants.   

[K0UA]

Why build something that is extremely iffy when good used Rohn 25 towers that are still in good shape are available free for the taking in most parts of the US. I have helped take down many, and never paid a dime for any of them. The days of dispatched 2 way radio at small business's is pretty much over since the invention of the pocket cell phone for many small/medium business's. They often still have the towers up because they don't want to pay to have them professionally taken down.  If you and a buddy have the proper climbing belt and gin pole and a 200 foot 1/2 inch rope, you can take them down all day. Chances are even if you don't climb or cant pull a rope, that hams in your area are "squirreling away" tower sections. My buddy that has the gin pole and belt has hundreds of feet of it. I didn't have the place to store any but I sure helped take down a lot of it.  We also passed up a lot of it too.

[N2SR]

Why build something that is extremely iffy when good used Rohn 25 towers that are still in good shape are available free for the taking in most parts of the US.

Because typical hams are cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap.

[K7KNX]

Used towers are a dumpster fire! I have helped scope the inside legs of two different towers, each one showed signs of corrosion.  These were both Rohn 25G that spent their life in the dry climate of southwest Idaho.  There is no way I'd every buy a used tower. The cost difference is less than the deductible for you ER list and followup DR. appointments!

[N2SR]

Used towers are a dumpster fire! I have helped scope the inside legs of two different towers, each one showed signs of corrosion.  These were both Rohn 25G that spent their life in the dry climate of southwest Idaho.  There is no way I'd every buy a used tower. The cost difference is less than the deductible for you ER list and followup DR. appointments!

My 130 feet of Rohn 45G begs to differ.  Purchased used after having been up for ~ 25 years.  I even helped take it down.  Got it regalvanized, and it has been vertical for 10 years now with zero issues.  There was no rust on the on or in the legs. YMMV.


 

[N1AUP]

I am looking for a web site of a ham that detailed the construction of this tower, with physcal measurment and angles. He used for the bending of the conduit some tool for small airplane construction.  I dont remember if he lived in California.

Thanks For any help

Athos
Kp4cb

Here is what I like to do for an antenna support.

I buy a 12 foot, 4x6, pressure-treated post from Home Depot.  I buy a quality, 2x4.  A piece of 10 foot, metal, 1.5 inch conduit and a piece of 1.25.

I telescope the two pieces of conduit about 1.5 feet, and  put a bolt through to keep them from collapsing.

I cut a four foot section of the 2x4, and bolt it with two carriage bolts to the 4x6.  I drill two muffler clamps into the 2x4, and mount the mast atop the 2x4. 

I bury the 4x6 about 3 feet into the ground.

I wouldn't mount a Mosley TA33 monster atop this, but it does a fantastic job for most VHF / VHF verticals, scanner antennas, or even a 10 meter ground plane.

I have three of them up, and they have been working great.

[N1AUP]

Why build something that is extremely iffy when good used Rohn 25 towers that are still in good shape are available free for the taking in most parts of the US.

Because typical hams are cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap.

I wouldn't even take the risk on a used tower.  But that's just me.

[VE7RF]

Several cases in the past, where rohn 25/45 was stuffed into the ground, hole filled  with concrete, and the thin layer of gravel at the bottom of the hole did not suffice to drain water coming down the inside of the hollow legs.
Bottom 2' of tower above the concrete was severely compromised.   In some cases, more concrete poured above the original concrete, to provide enough support, so the tower could be climbed..and dismantled.   

I have seen other towers, where water collected in the legs, then froze, then a 10" tall split up the side of the leg.   This was on tower sections that used pipe ( with a seam)..and had large square plates welded to the top and bottom of all 3 x legs. Typ, a small drain hole was drilled into each leg, just above the square plate.  Hole would plug from debris.

[SWMAN]

Jethro Bodine would be proud of some of you guys.

[K0UA]

Why build something that is extremely iffy when good used Rohn 25 towers that are still in good shape are available free for the taking in most parts of the US.

Because typical hams are cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap, cheap.

I wouldn't even take the risk on a used tower.  But that's just me.

Well, I have had many Rohn towers in my lifetime, and so have my friends, and I know for a fact I have never bought a new section of Rohn 25, and I don't believe any of my friends have either.  One does have to have the ability to look at the section and know when it is time to retire it.

By the way, ALL cars run on used parts. Every last one of them. They are used when you start them for the first time.  AND ALL towers in use today are used towers. The older they are the more "used" they become. Even my current tower has been up about 20 years, and it was built from used tower sections that were at least 20 years old before I put them back up.

[N2SR]

  AND ALL towers in use today are used towers. The older they are the more "used" they become. Even my current tower has been up about 20 years, and it was built from used tower sections that were at least 20 years old before I put them back up.

Where are you getting this information?  If you buy direct from Rohn or DXE means that you are buying used tower sections?   

I know several people who purchased brand new 45G and/or 55G tower that was absolutely brand new. 

[K6OK]

I am looking for a web site of a ham that detailed the construction of this tower, with physcal measurment and angles. He used for the bending of the conduit some tool for small airplane construction.  I dont remember if he lived in California.

Here is the tower you are looking for: https://www.qrz.com/db/WA6KJN/
Scroll about halfway down.  He describes a 36-ft EMT tower he used to have at one time.

I happen to be a Calif. P.E. and I've done tower structural analysis and wet-stamped custom designs for many hams.  I have to say this EMT tower is nicely done, quite clever and somewhat amusing, all at the same time.  EMT has a yield strength of about 20,000 psi while structural steel is 36,000 psi minimum.  Commercial towers often use 50,000 or 70,000 yield steel in the legs.  The low strength of the EMT steel coupled with the relatively small leg diameter of 0.75 inch will severely limit the overall strength of the tower. 

Is there a chance this tower might work as shown?  At only 36 feet and guyed at two levels this contraption might pass muster. I can't dismiss it out of hand without doing a full analysis but the odds are against it.  Regardless, definitely not a tower design I'd recommend, as others have pointed out, EMT is one of the worst materials one could choose for a tower or mast.

73 Jim K6OK

[K6JH]

I am looking for a web site of a ham that detailed the construction of this tower, with physcal measurment and angles. He used for the bending of the conduit some tool for small airplane construction.  I dont remember if he lived in California.

Here is the tower you are looking for: https://www.qrz.com/db/WA6KJN/
Scroll about halfway down.  He describes a 36-ft EMT tower he used to have at one time.

By the time you purchase, bend, drill, and bolt all that EMT, you might as well just go buy some Rohn 25G and do it right. With known specs.

I’m not above using fence top rail or something to make a mast holding a small vertical or dipole or something, but trying to make a full fledged tower seems a little excessive. I just wish the local big box stores would sell 20 ft lengths instead of 10 ft.

[K0UA]

  AND ALL towers in use today are used towers. The older they are the more "used" they become. Even my current tower has been up about 20 years, and it was built from used tower sections that were at least 20 years old before I put them back up.

Where are you getting this information?  If you buy direct from Rohn or DXE means that you are buying used tower sections?   

I know several people who purchased brand new 45G and/or 55G tower that was absolutely brand new.

And after the tower has been up for a month, is it a new tower or a used tower?  And how long does it need to be up for it to be a used tower? Month, year, decade?   Just like all "new" cars that drive out if the assembly plant are cars that now have "used" parts.  How long does it take for the parts to go from new to used?  I don't know.  My point is there is NOTHING wrong with putting up a "used" tower, and they are NOT a dumpster fire as long as the tower sections are inspected and are in good shape for re-assembly. That is my point and I am sticking to it.

[K0UA]

By the way a friend and I built a welded tower from TV "Duratube" and scrap strap steel bars. This was welded up with an old Lincoln 225 stick welder. This was put up at 100 foot, guyed at several points (can't remember how many, but think about 4) and it stayed up for several years as a tower for a local repeater.  Was It a strong tower?  No. Was it a great idea? No. We were young and we did it.

TV Duratube is WAY too thin walled. It was "heck" to weld to with a stick welder. A lot of practice was gained in filling holes with a stick welder in welding the straps to the thin walled tubing. Not to mention the rusting over a few years. I sure would lot rather have some 40 year old Rohn 26g up for a tower than that crap we made.  So do I recommend you make your own tower. NO.  Do I recommend you buy or get for free for the takedown some good Rohn 25g sections? YES.

Also beware of Rohn 20 tower sections. They are thinner and have one less zig zag brace. They will mate with Rohn 25g sections, but they are not as strong. They were intended to be used for lighter duty television arrays not heavy and large ham antennas.