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Author Topic: Rohn 25G tower and base  (Read 6509 times)
N4KD
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Posts: 131




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« Reply #15 on: August 27, 2013, 01:21:16 PM »

This is really off-topic and I apologize. But, to continue, Tom, did you get a concrete truck to deliver the 2 1/2 yards you needed? I'm just curious, as I'm really having trouble finding companies that want to deliver short loads.

Vy 73,
Dave N4KD

I just called up a company near where I live and they wanted around $400 for 2.5 cubic yards of concrete delivered...too rich for my blood...good thing I've got a mechanical mixer! Grin

I figure you'd need about 105 80# bags of Quickrete. Local price is about $3.50/bag. I think I'd take the ready-mix.

And W9GB, I'll have to make it clear that I don't care when it's delivered. That flexibility may be the key.

TU es Vy 73,
Dave N4KD
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K3GM
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Posts: 1767




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« Reply #16 on: August 27, 2013, 01:31:28 PM »

There's approximately forty-five 80lb. bags in one yard.  Sounds like fun!
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WI8P
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Posts: 256




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« Reply #17 on: August 27, 2013, 03:27:55 PM »

I am in the process of installing a used 25G now.  Mine will be 40 feet tall.  The Rohen base dimensions you quoted are for the 40g I believe, as the ones I down loaded from their site say 4' x 4' x 4.5' deep.  Those are the dimensions I used.  I also built a rebar cage on the 5 foot base section before putting it in the ground and pouring the cement.  I used 5, 10' sections of rebar, cutting each piece 3.2' (approx) long.  They are mounted on 12" centers.  To top it off, I used a fiberglass reinforced cement mixture.  Right now, I'm waiting for a crane to become available to mount the top two sections and the antenna.  At my age, I'm too old and fat to be climbing this thing, even though I know it would hold me.  Let me know if you have any questions I can help with.

KB1TOM
Tom

Okay...thanks for the info!  I'm going to go with a base of 3' x 3' x 4' since mine is only going to be 29' tall to be exact.  I'll also install a re-bar cage around the submerged section for added support.  I just don't see how over 3200 pounds of concrete will move with only a 30' tower above it...shouldn't be a problem unless we have a tornado come through.  What I am going to do after it's completely up is monitor it during the first few wind storms this winter.  If I see it swaying at all, I'm going to attach guy wires to it near the top.  I really don't have the room to put guy wires since they would run across my backyard and limit foot traffic, but if it comes to that, then that's what I would have had to do in the first place...

I'll have two options as to getting the tower up...I'll either walk the sections up with the help of a few friends, then lift it vertically and place it over the protruding section, or I'll attach a ladder and carry the sections into position (or borrow/make a gin pole)...I'll let you all know how this turns out...

I did get it delivered, but I also cemented two I-beams in the ground at the same time, so I needed 3 yards.  I also rented the power buggy instead of trying to wheel barrow the cement to the holes.  My back has been saying thanks every day since.
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WI8P
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Posts: 256




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« Reply #18 on: August 27, 2013, 03:34:40 PM »

...I'll either walk the sections up with the help of a few friends, then lift it vertically and place it over the protruding section, or I'll attach a ladder and carry the sections into position (or borrow/make a gin pole)...I'll let you all know how this turns out...

Please do.  By the way, what are you using for a climbing harness, and positioning and fall arrest lanyards?

My tower is only about 11 feet from my property line - but it was the only practical place to put it.  Because of that, I can't use the three wire guy system, and am going with four instead.  Two maple trees are going to be anchor points for two of the tower legs, while the side facing my lot line will have two of it's own.  I sunk two 12' I-beams in the ground and cemented them in place when I poured the base.  Overkill, I'm sure, but with the tower that close to my lot line, I want to make my insurance company and the housing inspector happy.
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WX4SNO
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Posts: 12


WWW

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« Reply #19 on: August 27, 2013, 03:47:26 PM »

Wish I could put an I-beam in mine!  I'll be lucky if I can get some re-bar to sink down into the ground below the concrete base...it's just so rocky here that stuff just doesn't want to drive in...I just broke the handle off my good shovel cause of all the rocks, so I'm done for the day.
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WX4SNO
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Posts: 12


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« Reply #20 on: September 21, 2013, 02:29:42 PM »

Got the 30' tower installed...a complete success and no injuries. Grin  In fact, the process was rather smooth and the only hard part was getting the tower past the 30-70° mark...once we got it vertical it was a piece of cake to lift 6" off the ground and onto the protruding section.  The base was poured over 3 weeks ago and is 3'x3'x3.5'.  Too bad I didn't have a video camera, but my weather webcam caught the whole process minute-by-minute...

http://youtu.be/Jw707DMzsBE

Even my in-laws said it was easier than they thought/looked.  Anyhow, wanted to update this thread and let folks know that it can be done easily and safely...as long as you have the right equipment (several 2x4x12 screwed together and notched, plus some scaffolding) and some friends to help you out.  I wouldn't have attempted this on my own...it would have been a disaster then.  Here's some images that everyone should be able to access:

https://www.facebook.com/media/set/?set=a.10151663528566305.1073741825.637366304&type=1&l=3c122cebbf

73,
WX4SNO
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LA1BRA
Member

Posts: 49




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« Reply #21 on: September 22, 2013, 06:45:20 PM »

Do check big box stores for a cubic yard on sacrete and then tell us if the delivered price was better than mixing it yourself. However, i think sacrete is only 3000 psi mix, you really need to look at the foundation specs, I recall they call for 5000psi mix...
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KC4MOP
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Posts: 729




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« Reply #22 on: September 23, 2013, 03:55:43 AM »

I'm actually not planning on climbing it (I hate heights), rather a group of friends and I will walk the tower up into position...would this not work (small 144/440 and a scanner antenna) for an un-guyed tower that I DON'T plan on climbing?  I won't be bracketing it to the house because I'm interested in keeping the WMO standards for the anemometer (1m tower away from buildings) and I know the Weather Service uses unguyed towers for their meteorological instruments...would I just need a larger concrete base?
Walking 30 feet up to a vertical position is not very good either. It puts a lot of stress on the structure. Get a tree company to install it with their bucket truck and yes, the larger hole is goodness. I lucked out with a contractor who used his back-hoe to dig my hole. $25 and 5 minutes there was this nice big hole. 3 yards of concrete, for my 30 footer.
Fred
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LA1BRA
Member

Posts: 49




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« Reply #23 on: September 23, 2013, 04:37:05 AM »

It turned out the company that delivered the concrete was doing some other work in the area, that's why they were able to add the extra 2 yards to the load, agree, hiring a truck for small loads not cost effective, you might have to wait till there is another job in your area...tom
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