[SixClub] tower questions

[Roger (K8RI) on Six]

I'm not sure about guidance, but I can offer some opinions.

When you said "cost effective", I'm assuming you are on a budget of some 
sort.  Every one of us has a budget whether it's formal or informal and they 
vary from using a piece of pipe to, "That thing cost how much!"
You really need to define what you mean by cost effective. Things like 
expected life, reliability, load handling ability compared to what you plan 
on doing, and how much room you have all need to be taken into account.
Oft times, the least expensive route is not the most cost effective.

So, with not much for me to go on I'd say you can approach this from two 
directions.  What you want to do and how much you can afford.

First, I'd strongly suggest you stick with the installation instructions, or 
engineering requirements for any particular tower as stated by the 
manufacturer.  ROHN has a very good catalog and I believe web site that 
includes the engineering specs and ratings for their tower installations. I 
think you will find that most on this group tend to be on the conservative 
side when it comes to safety and regulations.

Having said that and not that I'd recommend it, but for years I ran a 90' 
American Steel heavy duty TV tower with a dirt base. It was holding a 
Cushcraft ATB34 and TV antenna. The system used 4 point guys at three levels 
and was up at three different locations for a total of nearly 30 years 
(using the same physical base). After all that it still wasn't rusted 
although due to wear from climbing it had to be repainted twice.   I really 
wouldn't recomend this approach be used for more than 40 feet and it also 
depends on your soil conditions.  Zoning  and/or your insurance company may 
or may not play a part as well.

The least expensive way would be to find a used tower (guyed) of suficient 
strength "in good shape" of the height required. This really requires that 
some one familiar with the field give the tower a good inspection. Be 
careful of tower legs that have had water freeze inside of them.  Any 
deformed legs or cross braces are also warning signs.  Sure, most can be 
rewelded, but they steel or aluminum, but is something strained the tower 
enough to deform it in the spots found you have to stop and ask what else 
may have been strained, but doesn't show.

Add to the tower an adequate ground system which is usually neglected by 
most hams with typical 30 to 40 foot tall systems.  A good ground system is 
essential for safety and to me that means one rod about a foot out from each 
leg and then a heavy copper cable running out from each leg with a series of 
ground rods.  Again, cost quite often limits the size of the ground system. 
So far the current system has taken lightening strikes an average of three 
times a year.  Since finishing up the ground system I've had no damage even 
from direct strikes.

The next step up would be a new, guyed tower rated for the wind load and 
winds in your area.
Typically, guyed installations are less expensive than self supporting, but 
there are exceptions with some of the shorter installations.  As the tower 
gets taller the amount of concrete for the base gets larger and that amount 
of concrete gets larger faster than the tower gets taller. OTOH as you go 
taller for a self supporting tower the tower gets larger and heavier the 
taller it gets.

Even ROHN 45G is not rated for much as a self supporting tower, but it'd do 
a nice job at 30-40 feet with a small tribander. I mention 45G as one of the 
locals had well over 200 feet of the stuff that was like new and it went 
*cheap*. Of course I only found out about that "after" I had purchased a new 
97 footer, plus acessories.

Self supporting towers and by that I mean towers that are designed to be 
self supporting are usually the most costly route at more than 30 feet or 
so.  OTOH they may be the only route available.

Centrally located in the city of Midland there is a 160, or 170 foot self 
supporting cell tower.  It's the kind that looks like a pole until you get 
close enough to see just how massive the thing is.  It's in the corner of a 
parcel for a grain and food store.  The base is 30 feet deep and I don't 
know the diameter of the hole, but it was dug with the largest auger I've 
ever seen and there are truckloads of concrete in there.

My tower project http://www.rogerhalstead.com/ham_files/tower.htm gives an 
idea as to what I went through to install the system here.  I saved a lot by 
doing the work myself, but my only alternative would have been to hire a 
construction company that does this kind of work.

As an opinion, for a small tribander, or VHF and UHF antennas,  I'd go 40 to 
50 feet using a guyed  ROHN 25G set in as much concrete as they recommend. 
Use guys of the proper strength as recomended by ROHN and in the 
configuration they recommend and don't forget the ground system. <:-))

Good Luck,

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com

> Now could I get some guidence on towers? I never owned
> one before and I was wondering the most cost effective
> ones are? is there even such a thing?
>
> thanks,
>
> Ben, K0BLR
>
>
>
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