• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

getting ready to put in a tower... have a few questions

mr_fx

Sr. Member
Oct 8, 2011
1,537
172
173
Kansas City
I am getting ready to install a 50 foot aluminum telescoping tower with a tilt base... it will have a 7 element 10 - 15 - 20 meter beam, and maybe a 6 meter and 2 meter beams as well as my 8 foot 2m/440 co linear

I may also be setting it up as an 80m vertical, and maybe even a loaded 160 (with a 64 or so ground radials system)

So how much concrete do I need on the base of the tower? And how much concrete would I use on the guy points?

How deep down do I need to dig the hole, and for some reason I recall hearing about filling the bottom of the hole with gravel
 

cycleguru

W9WDX Amateur Radio Club Member
Aug 4, 2013
34
5
18
Yes, the tower's manufacturer should have recommendations and probably even diagrams showing just how to construct the base. I put up a MA-40, 20/40 foot tubular telescoping tower (non-guyed). Dug the hole approx. 3x3x3 feet. Didn't get down the full 3' because I hit rock. I built an internal frame out of rebar and placed it in the hole. It's been a while, but I think I used about 20 to 25 80lb. bags of sack-crete to fill it. While the concrete was still soupy I sank (4) three quarter inch x 18" J-bolts matching the hole pattern in the tower 's base (to bolt the tower down to the concrete pad). I way overbuilt this compared to U.S. Tower's plans, but I live in a wind tunnel.

Hope this helps.

73

Mark K7OWG
 
Last edited:

KG0MN

W9WDX Amateur Radio Club Member
Mar 5, 2010
166
42
38
For my 50" I did 5' x 5' x 5' and I hand dug. Main this to remember is center it in the hole (you would be surprised how many forget this when the tower is close to a building) and then use a lot of rebar that is tied together with wire. Run some vertical, horizontal and at 45 degree angles.
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,875
11,060
823
59
Nova Scotia,Canada
I am getting ready to install a 50 foot aluminum telescoping tower with a tilt base... it will have a 7 element 10 - 15 - 20 meter beam, and maybe a 6 meter and 2 meter beams as well as my 8 foot 2m/440 co linear

I may also be setting it up as an 80m vertical, and maybe even a loaded 160 (with a 64 or so ground radials system)

So how much concrete do I need on the base of the tower? And how much concrete would I use on the guy points?

How deep down do I need to dig the hole, and for some reason I recall hearing about filling the bottom of the hole with gravel


We cannot answer that without knowing the tower model. A tilt base requires a larger base than a simple vertical tower because of the leverage exerted when the tower is tilted over. That is also a fairly large load at the top that you have planned for it making it even heavier to tilt over placing even more stress on the base. Your best and safest bet is to follow the manufacturers recommendations. You will need several yards of concrete for a tilt base and I do not recommend using something like Quickcrete to do it. You will be surprised at just how many bags it will take. Calling a cement company is the way to go. My 64 foot free standing tower took about six yards which is equivalent to over 360 sixty pound bags of Quickcrete. :headbang Needless to say I called Quality Concrete for 6 1/2 yards of 3500 lb. PSI foundation mix.
 
Last edited:
  • Like
Reactions: 1 person

GnG8d

Well-Known Member
Jun 28, 2010
2,037
344
93
Ohio
For my 50" I did 5' x 5' x 5' and I hand dug.

Damn, that's like 4.5 yards and 15,000# of concrete. I went a little over a yard at 3'x3'x4' on my 70' tower, but I'll do 3' dia x 4' deep next time, which is right at a yard. I used screw in ground anchors and Dacron rope for guys.

I've had to clean up 7 trees blown over since then and my antenna is still in the air.
 

GnG8d

Well-Known Member
Jun 28, 2010
2,037
344
93
Ohio
A tilt base requires a larger base than a simple vertical tower because of the leverage exerted when the tower is tilted over.

If the lifting point is mounted in the same hole, I'd say yes. But not if the lifting point is anchored in a separate chunk of concrete.
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,875
11,060
823
59
Nova Scotia,Canada
Damn, that's like 4.5 yards and 15,000# of concrete. I went a little over a yard at 3'x3'x4' on my 70' tower, but I'll do 3' dia x 4' deep next time, which is right at a yard. I used screw in ground anchors and Dacron rope for guys.

I've had to clean up 7 trees blown over since then and my antenna is still in the air.


Yeah but you have a guyed tower. A guyed tower only needs enough concrete to support the weight of the tower. A freestanding tower requires MUCH more concrete in a much larger base. My 64 footer called for a hole 5 1/2 feet square and 6 feet deep. I hit solid slate at 5-5 1/2 feet and bonded the concrete to it using driven rods.
 
Last edited:

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,875
11,060
823
59
Nova Scotia,Canada
If the lifting point is mounted in the same hole, I'd say yes. But not if the lifting point is anchored in a separate chunk of concrete.


Again, it all depends on the tower model. Some have the winch mounted on a short base section and others have it mounted on a separate lifting jig located in a different location. Others simply fire up a vehicle and don't use a winch of any kind. You also have to take into account the forces of the tower pushing back against the base as it is lowered if a separate raise/lower point is used. As the tower approaches horizontal there is a huge amount of force being exerted back towards the lifting point and the base has to provide the support for it. In any event the manufacturer knows best.
 

GnG8d

Well-Known Member
Jun 28, 2010
2,037
344
93
Ohio
I missed a lot here on my phone, but I just cant see the need for 15,000-25,000# of buried concrete for any of these installs. That's insane.
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,875
11,060
823
59
Nova Scotia,Canada
I missed a lot here on my phone, but I just cant see the need for 15,000-25,000# of buried concrete for any of these installs. That's insane.


Cured concrete weighs about 3600 pounds per cubic yard depending on the actual content and reinforcing. My base therefore weighs about 20,000 lbs. give or take. Not at all unreasonable for a free standing tower designed to support 52 sq.ft. of wind loading. It is a Trylon Titan T-500 series.Anyone that is used to guyed towers is often amazed at what it takes to install a free standing tower PROPERLY.All a guyed tower needs is something that will support the weight of the tower and the downward force exerted by the guys. The thing is not so much the weight as it is the area and more importantly the depth of the foundation which should be below the frost level.. This all adds up to a great weight. There is NO WAY a reasonably tall free standing tower will stay up with only a single cubic yard of cement in the base.The leverage exerted on the base is just far too great. It will literally up-end the concrete block. I know of one 64 foot high tower where the owner went cheap on the base. After a good old fashion nor'easter the tower was leaning about two or three feet out of line. The Delhi tower was still straight and the antenna (PDL-2) survived but the base began to lift and rotate in the hole causing a permanent lean. It remained up for a few years after and then was taken down when the operator got out of radio.You can shun the idea all you want about the size of required bases for free standing towers but until you look at the physics of it and read up on the way things should be done you will never fully understand what is going on and the difference between free standing and guyed towers. They are like night and day in their installation requirements and hence both have their advantages and disadvantages. The greatest advantage a free standing tower has is smaller footprint,no guy wires spread out, and no guys to interfere with antenna installations. They do tend to be more expensive however. Personally I prefer free standing and would never own a guyed tower for at least the two reasons I just mentioned about the guys.
 

GnG8d

Well-Known Member
Jun 28, 2010
2,037
344
93
Ohio
I'm not shunning anything, I've read some of the spec sheets and I'm more mechanical than electrical. I completely understand guyed versus free standing versus tilt and the forces exerted. But this all reminds me of industrial overhead cranes which will lift twice their rating and do it safely. I think a lot of these specs are written for the guys living in the Keys with loose sandy soil and not hard packed clay soil. But I don't pay their legal fees either, so common sense prevails.

I want to see the peice of equipment it takes to pull a 25,000# block of concrete out of the ground without digging is all <More audio>
 

Lil'Yeshua

.......
Nov 22, 2012
4,625
305
93
Pageland,S.C.
Enough concrete to counteract wind loads. I have 2 1/2 cu. yrds of concrete that my 31' tower with an additional 7' mast and antenna array totaling 53' in height. It's overkill but it held up in Hurricane Floyd and numerous T-storms. I think that my tower may have the capacity to extend the tower an additional 20'. All of the weight is straight down unless it exoeriences side loading. There are websites that you can go on and find out what size footing is needed as well as on this forum. Footing shape is crucial too. I delivered concrete to cell tower footings. Cell towers have a wide footprint in order to counteract wind load forces acting on cell towers. And average cell tower footing may have over 132,000 lbs. of concrete.

Safety ,safety,safety. You got to think about what if you built a shoddy erected tower and if it were to fall on someone.
 

GnG8d

Well-Known Member
Jun 28, 2010
2,037
344
93
Ohio
An inverse pyramid would work well for dispersing the load while saving weight. I've seen people dig back the walls trying to in effect make a pyramid, but I think and upside down pyramid is stronger if the concrete is up to the task. You don't have to think as much about the direction to load is heading to as much as the direction the load is pulling from.
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,875
11,060
823
59
Nova Scotia,Canada
You don't pull a 25,000 lb block of cement out of the ground. You tip it over by providing a large force at 40,50,70 feet etc, from the base and using the standard ft lb calculations you generate a tremendous rotational torque at the base.Case in point here. My Hygain Explorer 14 presents a wind load of 192 lbs. in an 80 mph wind. Mounted at 65 feet that means 12,500 ft. lbs. of rotational torque at the base plus the wind drag over the length of the tower not to mention the other antennas mounted on it. If the ground has been saturated by rains etc then it can move if it is too small. Of course as with everything there is a safety factor built in and it depends on the soil conditions at each site. Unless one has a degree in soil mechanics or geotechnical engineering and can properly analyze their soil conditions and install exactly to their own local conditions then you pretty much have to follow the general recommendations from the manufacturer. My base is actually a bit smaller than the manufacturer recommends. This is because I encountered a bed of slate about 2 1/2 feet down. The top foot or so of this slate was soft and relatively easy to break out with an electric jackhammer I had rented. Down about 5 feet it was very hard to break up and extract from the hole. I used a pressure washer to wash the sides of the slate bed cleaning out any stones plugging uo the layers. This allowed the concrete to really grab good into the layers of slate. I also drilled a couple holes into the slate and drove some metal rods in at an angle. This anchored the concrete base to the slate bed making for a very strong base even if it was a bit smaller than the recommended size.I also made the hole wider at the base than at the top to make it somewhat bell shaped to make it harder to want to lift. If it had been all sand it would have been a different matter.


This is what I had to contend with. On the left side you can easily see the line where the slate starts. This is before I washed out the loose stones and drilled the bottom of the hole.


img2293x.jpg
 

dxChat
Help Users
  • No one is chatting at the moment.