[TowerTalk] tower replacement wisdom

[Charles Morrison]

Having done a 120ft 140 MPH tower last year I grabbed my costs and applied
them to your plan:

NEW PARTS  170ft 130MPH 55G 4-guy levels no insulators

$2500 for new Rohn anchor rods  GAC5755TOP  $825 ea +ship
$400 rebar -pickup
$200 lumber -pickup
$6000             17 new 55G sections +ship  (Find used and save 50%, but
life is reduced.)
$1500             All other Rohn parts   BPC55G APL55G (4) GA55GD    +ship
$ 315              700 ft  5/16" EHS  $0.45/ft  +ship
$ 475             1575 ft 1/4" EHS  $0.30/ft  +ship
$   48               6  5/16" Guy grips / Big Grips $8 ea +ship
$ 108             18  1/4" Guy grips / Big Grips $6 ea +ship
$ ~500           Thimbles, Shackles, End sleeves/ice clips.  +ship
$ 200              Bolt cutters pickup
$ 425              12   3/4TBE&J Galvanized Turnbuckles  $35 ea +ship
$ 100              Safety Wire & parts +ship
$ ???              Grounding +ship

You build guywires  2-3 days 1 man.
Tower crew:     Remove ants & cables
 Tower crew:    Demo tower ( release 1 guy) cut up for scrap, (You could do
all of this & haul away)
$500-1000       One day anchor hole prep $500-1000  Rohn AB3
                        Build rebar cages  1 man 2-3 days
$ ???                6-to-8 yds 4000 psi concrete  +ship
 Tower crew:    Erect tower
  Tower crew:   Install new feedlines and old antennas
=============
Totals:
New Parts discounted retail $13000 + Tower crew ($5000-$10000) + new
feedlines and associate parts + backhoe + shipping + concrete
+ your free labor listed above.
Guess: $25000 to $35000

-Charlie N1RR

On Thu, Jul 18, 2019 at 7:01 PM Matthew Kaufman <matthew at matthew.at> wrote:

> Hoping to gather some community wisdom before embarking on a tower
> replacement.
>
> I have a 2.5 acre property on a slope with what I believe to be a Rohn 55
> tower that was installed as a commercial paging transmitter tower in 1971
> at 150 feet, then extended sometime in the 1980s to 170 feet when they
> switched from VHF to UHF and then 900 MHz paging. (The top (5th) guy level
> was quite clearly added using an existing hole on the anchor and a
> strandvise instead of the big grips that were used for the other guys.)
>
> The tower has withstood at least one lightning strike, the 1989 Loma Prieta
> earthquake, and numerous storms,... but the guys are getting very rusted,
> the tower is rusting (despite a coating of zinc-rich paint a couple years
> ago), and the guy anchors are in unknown condition (though visually "ok").
> I'm not sure how long a tower should last, but it can't possibly be
> "forever".
>
> Two of the guy anchor locations are just above the tower elevation, the
> third is some tens of feet lower. Each guy anchor has a metal rod that
> extends 3+ feet unprotected through dirt and then into a concrete block .
> The tower has a pier pin base on concrete which is below ground level, so
> is in a bit of a well with retaining blocks around it (had been buried
> under the earth when I acquired the property and tower).
>
> I have the following limitations:
> 1. I want to have minimal downtime - the tower has a couple of heavily-used
> ham repeaters, a commercial repeater, and a wireless ISP on it.
> 2. The county would never issue a permit for a tower like this today... the
> property has a use permit for the tower, specified as "18 inch face" and a
> drawing of its approximate location on the property. So I need to somehow
> permit this work as "replacement in kind". A new tower would be limited to
> 53 feet in this zoning district, with a possible variance available to 78
> feet... the trees are taller than that.
> 3. I have no construction drawings for the guy anchors or the tower base,
> and have no way of nondestructively testing the strength of the guy anchor
> rods.
> 4. I'd like to ensure that the tower can support the existing and future
> microwave dish loads, and reduce the twist both for those and the fire
> detection cameras I have up top... so maybe should go to star guying?
>
> So... I need to choose a tower that is roughly 18" face width (possibly
> just Rohn 55 again), and install it at (if I trust the foundation) or near
> the existing tower location, with presumably new guy anchors that must be
> near but not at the existing anchor locations (to minimize downtime), and
> do as much of the removal and installation as possible with a crane (or
> helicopter?). I also need to not break the bank, as this is really a hobby
> tower for me, where the commercial customers are mostly to pay the
> utilities and property taxes.
>
> Thoughts? Alternatives?
>
> Matthew Kaufman, KA6SQG
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