[TowerTalk] Utility Poles

Pat Barthelow aa6eg at hotmail.com
Sat Apr 28 04:01:46 EDT 2007


Folks,

I agree fully with Paul.
When building and maintaining the N6IJ contest station with which the Army 
blessed us at the site, with numerous 70' wooden poles, mostly installed in 
the 60s, I investigated the safety and capacity of wooden poles.  The 
reference manuals for wooden poles that the Army and Power industry had, 
amazed me.

I recall that the Class 1 or class 2 poles that we had, could withstand a 
1200 lb HORIZONTAL  load near the top of a 75 ft pole, buried 11 ft in the 
dirt, with no concrete necessary for a foundation.
(This is assuming the particular dirt we have at N6IJ will withstand the 
loading. which we never did the testing.  The pole strength was awesome.)

I wonder how much wind on, say a  15 square foot antenna would be required 
to push, say 800 lbs?  Take into account the additional square area, of the 
pole, about 12" dia.   Local line men told me that under good soil 
conditions, and maintenance  (preservative injection, as necessary)  the 
tower base stays structurally sound easily 40 years.
Some soils/biologics can cause more rapid deterioration.  Those at N6IJ were 
of that age, and many had little injection taps near the ground level  that 
the crews used to periodically inject additional preservative.   (See 
http://www.n6ij.org for antenna farm pictures )

If you need to determine how deep an existing pole is buried, the 75 footers 
have a data plate mounted the standard 15 ft above the base.  Shorter poles 
sometimes have the data plate mounted 10 ft above the base.  A rule of thumb 
from the manuals, on how deep to bury the pole, assuming the earth is 
capable of strong support, and is properly tamped, was 10 percent of the 
total length, plus 2 ft.

All of our poles had pole steps, making them easy and safe to climb.  We 
were priveleged to have been given permission  to raid a surplus yard at Ft 
Ord for pole hardware which we were able to do minor additional assembly and 
fabrication to make mounts and supports for beams and rotors.  Such hardware 
is probably not cheap to buy, but in small quantities would not be a 
significant fraction of the overall iinstallation.

A major manufacturer of wooden poles is McFarland.
http://www.ldm.com/
They have a very good website, for determining size, weight, cost, for 
poles.
I priced from McFarland,  about 9 years ago a Class 1 (thick) 120'  treated 
preserved pole, with climbing step holes drilled, and delivery costs and 
came up with  a quote total of $7000 delivered to the site  (horizontal on 
ground, at site, erection extra)  It would easily hold ANY ham beam antenna 
at that height, without guys or concrete.  (assuming good structural earth) 
The delivery was from various Forest locations, depending on destination 
location and they charge by the mile.  (120 ft pole has obvious difficulties 
with transportation and McFarland had to plan routes carefully in advance, 
and I think it took 2 trucks.   I think the pole cost was $3K, and transpo 
costs were around $4k from Idaho to Monterey.  The weight was quite awesome, 
I think around 10K lbs.  All details can be found at McFarland's website.  
So, add some additional costs, and say, you could easily get a massively 
strong 120 footer tower installed  for under $10K,  I think that is a lot 
less than a steel tower.


73, DX, de Pat AA6EG aa6eg at hotmail.com;
Skype: Sparky599
Moon or Bust!--Jamesburg Gang Rides Again!
>From: "Paul Darwactor" <phd73 at mindspring.com>
>Reply-To: phd73 at mindspring.com
>To: towertalk at contesting.com
>Subject: [TowerTalk] Utility Poles
>Date: Sat, 28 Apr 2007 03:02:22 -0400
>
>For those who think a utility pole has no utility for ham use, I would 
>submit the following.
>
>I am using a class 3, 65 foot utility pole that was installed new in 1984. 
>It is pressure
>
>treated and requires no maintenance. For the past 23 years it has supported 
>stacked
>
>beams totaling 25 square feet of wind load with out concrete foundation or 
>guy wires.
>
>It's condition is as solid today as the day it was installed. I was told by 
>the company that
>
>provided it that I could expect 100 years of useful life. I don't expect to 
>be around long
>
>enough to test the warranty. Should I need to remove it I can employ the 
>truck that
>
>installed it to spend about 30 minutes to remove it and refill the empty 
>hole. New owner of
>
>the QTH will never know it was here ! For my money it beats the best of the 
>many steel
>
>and aluminum towers I have owned over my past 54 years in Ham Radio, hands 
>down .
>
>Just my severely devalued dollars worth.  YMMV.
>
>73 de Paul W8ZD.........................................
>
>
>Paul Darwactor
>phd73 at mindspring.com
>Why Wait? Move to EarthLink.
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