Bob, AD5VJ asked a question about a concrete base for a Rohn tower.
When Bob, NA6T posted this reply I thought the amount of concrete sounded a bit
high. I checked the Radian site and sure enough that is what is listed. So I
drug out my old Peoria Rohn Catalog, circa 1983 and researched base dimensions.
Peoria Rohn specs call for a 2' X 2' by 4' deep hole for the tower that Bob,
AD5VJ is installing. It calls for guy anchors of 2' X 2' by 1' deep.
Which raises the question: Did Radian re-engineer the base dimensions or did
the fear of litigation cause Radian to up the numbers?
I've installed two towers for myself, both Rohn 25G, both in the 30' to 40'
range ( I use a full section for the base) and both were planted in 2' X 2' X
4' holes. Neither came down (yet). In fact the one I have now is planted in a
2' round by 5' deep hole dug by the local electrical contractor with a auger in
about 15 minutes for $75 (THE way to do it).
Second question: Have I been overly lucky or is 4' X 4' X 4' a bit of overkill?
Clint - W5CPT
----- Original Message -----
From: Bob Smith
Sent: Tuesday, June 26, 2007 12:13 PM
Subject: Re: [TowerTalk] TowerTalk Digest, Vol 54, Issue 105
if you look at the self supporting Rohn 25 Tower detail drawing on
the link below you will see that the
foundation will be about 2.4 cu yards.
Then in the descriptions on the page click on the "Foundation Details"
There are about 36 'redi-mix' bags in a cu. yard ( 2/3 cu ft per bag)
so you are going to need a whole lot of bags of redi-mix. Call a
truck and get the concrete dumped in
the hole. You will also need rebar, either single lengths or you
can wire up a cage with the rebar. I've found
threaded Galvanized rod that is 5/8" or 3/4" in dia that is about 4'
long that I've used for the vertical sections that the
tower base is bolted to. This way you can drop the complete cage
into the hole, level it and pour the concrete
in the hole and everything is done. Be sure to have good drainage
from the base to the ground so you will not
have any standing water on the base. Be sure the base has a good flat
area of concrete to sit on.
The other way is to use a section of rohn tower in the hole and just
pour the concrete around the tower section.
Also be sure that the bottom of the hole as good drainage with sand
or gravel in the bottom of the hole. This way
any water that gets inside of the tower sections drains out the
bottom of the tower in the hole. Don't do like a
lot of people do and just put the tower section or cage on the floor
of the hole in the dirt and pour the concrete
I've got some pictures of a cage I use for rohn25 if you would like
to see them, drop me a line and i'll send them
hope this helps,
Robert Smith Consulting
"Wireless Installations -- Government, Businesses & ISP's"
F.C.C. Licensed-Commercial & Amateur Services
ARRL Life Member
1-707-964-4931 w/answering machine
Fort Bragg, California 95437
"On The Air-Conditioned Mendocino Coast, In REAL Northern California"
No trees were destroyed in the sending of this message.
However, a large number of electrons were terribly inconvenienced.
Date: Mon, 25 Jun 2007 19:17:36 -0500
From: "AD5VJ Bob" <email@example.com>
Subject: [TowerTalk] Ready Mix Cement
Content-Type: text/plain; charset="us-ascii"
I am planning a tower installation (40 feet Rohn 25) and am wondering
how deep the hole should, how big in diameter and how many
bags of ready mix cement I should buy to fill the hole.
Also wondering if I should use rebar and if there is a brand of
cement better than any other brand and what mixture of cement or if
the one for standard sidewalks, driveways, ect will work or if there
is a special mixture to use for a tower installation.
It is my first tower to erect.
Probably one set of guys wires (size, type of material??)
I will be mounting an old refurbished Hornet tribander, Ham IV rotor,
TitanDX vertical at the top and a VHF/UHF vertical on the
73 fer nw es gud DX,
QSL VIA: BUR, LotW, e-QSL
Old calls: WY5L/KH3-KE5CTY-N5IET
Member: CTDXCC, NTCC, STXDXCC
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