[TowerTalk] [Bulk] Installing DB36 atop 75ft guyed tower?

Fri May 8 12:04:45 EDT 2015

At 17.5 sq ft and 160 lbs a DB36 is a lot of antenna.  There are several 
ways for it to get to the top of the tower:

1. crane - easiest & fastest if you have access and are willing to pay 
for an hour of crane time - a recent local LM354 tower lift then lift 
and attach a DB18E, was $400.  I have a quote for my 140' R65 lift, 5 
hours with a 160' 6 ton crane, $1k.  A large sign truck might be 
available for a 70' lift at less than $400.

2. boom lifts are available to 100' from rental yards.  You and antenna 
and tools in the bucket must weigh less than the (usual - check it) 500# 
bucket rating.  A one day rental for an 86' one here cost me about $800 
including delivery and pickup.  An insurance binder might be required if 
you aren't a bonded contractor.  A 40' lift will easily reach the top of 
a nested crank up's mast and are cheaper and easier to rent.  An 
advantage of a boom lift is the ability to work on problems out on the 
boom or elements without taking down the antenna.  Nice when I found a 
boom guy was slipping.  I made a steel bracket to carry my 40m beam 
safely on the bucket on a 40 footer and very carefully and slowly mated 
the boom to the mast on an HDX589.  The antenna was always secured and I 
never left the bucket.  Also, when you forgot something, or have the 
mast to boom plate on the wrong side like I did, a ride in the bucket is 
a lot faster, easier, and safer than a climb.

3. side hoist.  Drop one guy one at a time, with mates slacked and hoist 
the antenna boom vertical up the side of the tower.  Tailing lines and 
handlers are needed, three are ideal to keep the elements out of the 
other guys and boom slightly off the tower, and you need to figure out 
how to get the tag lines out on the elements off.  You will need rigging 
on the mast to tip the antenna over and stabilize it while bolting it to 
the mast.

4. crank up - 17.5 sq ft may require an upsized crank up.  UST will 
upsize sections , eg HDX589 becomes HDX689; a HDX572 and HDX672, but 
prices go up significantly.  The antenna goes up side hoist (boom can be 
horizontal since there are no guys), crane, or boom lift.  A 160# 
antenna plus weight of a strong enough rotator and mast adds a lot of 
load if you want to tilt up the tower with the antenna on the mast.  I'd 
judge that can NOT be done for a DB36 with the UST tower raising fixture 
from the load I experienced on a 589 with an Orion rotator and 20' mast 
installed.  A crane can lift it easily if attached near the top of the 
tower and a ladder or short climb with the sections blocked can 
disconnect the crane.

5. Tram - two types:
A. The pros use a steel cable that runs from the tower to an anchor 
point that keeps the catenary above the guys of concern.  With a strong 
mast the attachment can be on the mast above the antenna mounting point. 
NEVER use a gin pole, they can't withstand much side force.  A carriage 
or for smaller antennas a pulley runs on this cable with a hoist rope to 
the carriage, to the tower, thru a pulley, and to manpower or a winch or 
power capstan at the tower base.  For a 160# antenna a capstan winch is 
probably needed or another pulley attached to the tower base to a 
vehicle (which has some hazards).  Again, rigging is needed to manage 
the antenna getting from the carriage to the mast.  500# chain hoists 
(lever or chain loop) are a good way to manage something as large as a 
DB36. They have short head room, fine inching capability, and shouldn't 
ever be set to freewheel. You never want to try manhandling anything 
heavier than 30# or so or you and the antenna might depart the tower 
together.  K7LXC's Up the Tower has a nice drawing of how this is done.
B. Two ropes are rigged as a bridle to a spreader on the mast.  The 
lines are above the guys of concern.  The antenna elements or boom ride 
on this as a third line to a pulley on the mast pulls the antenna up.  
In either case the center of gravity needs to be kept centered between 
the bridle lines.  Some tag lines are used to keep the antenna centered, 
but this is a difficult and tricky alternative.

Big antennas require very careful planning for each stage of the lift -  
how am I going to get from A to B; B to C, etc. safely with the load 
under control at all times?  Do I have a ground crew that understands 
the process, is physically capable, and communication is clear and 
clearly heard at all times, etc.?  Do I have all the parts, spares for 
dropped nuts or tools?  Is everybody wearing a brain bucket and the 
appropriate safety gear?  What is the backout plan if something isn't 
right - you can be sure of that?  Is the physical endurance of the 
workers up to the job?  Are the tower parts, guys, mast, etc. able to 
safely handle the loads the lifting will place on them?  Is the wind ok 
at the top of the tower?  Any bees or wasps  looking for some fun? etc.

There may be other techniques, but these are ones I've participated in.

Grant KZ1W

On 5/7/2015 18:57 PM, Jim Miller wrote:
> I'm evaluating options for a future station. I'm thinking a Steppir DB36
> with the 80m dipole would be a likely choice atop a 75ft tower. I'm
> evaluating the possibility of either a crankup/tiltover or something like a
> Rohn 55.
>
> I'm wondering how something as complex and heavy as a DB36 would be
> installed on a guyed tower with all the obstruction of the guys. One way
> would be to get a crane.
>
> Are there others?
>
> Thanks
>
> Jim ab3cv
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