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@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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