[TowerTalk] What is the highest you would setup a Rohn 25 as a temporary tower?

[Grant Saviers]

"with guys of course", the only limit is the spring rate of the trailer 
and the load rating of the tires.  The guy down force can be 
substantial, so you might need to block the trailer so the load is not 
on the tires/springs.  Finding something to tie the guys to will be a 
huge problem.

I have a Will-Burt 42' pneumatic mast guyed into a trailer or the bed of 
my 3/4T truck.  The mast is rated for 10 sq ft antenna, 140lb weight, at 
60mph fully extended.  My calcs show this load will tip over my 3/4T 8' 
bed extended cab 4WD truck (5000#).  For the hydraulic dump 10K# GVW 
dual axle trailer, which weighs 2300#, I have 40" long outriggers at 
each corner of the 6'x10' bed and 3500lb trailer jacks at the end of 
each outrigger.  The outrigger beams are not sized for the max tower 
load/wind speed and enable the trailer to be leveled so the tower is 
vertical.  My plan is to not have the mast up in more than 35mph winds 
which is the max load for the beam section/cantilever length I used for 
the outriggers.  Otherwise, the outriggers need to be long and heavy and 
probably need to be made as a truss.

This mast on the trailer played well at Field Day with a CC A4S at the 
top.  btw the air pressure was only 12psi for full mast extension with 
the A4S and Yaesu rotator.

There are pickup pulled boat trailers from 500# to 20,000# capacity, so 
you need to do some calcs to size the max tower loads. Generally, since 
the legal max width without oversize permits is 8'6", outriggers will be 
needed and that is another structural design problem.

Trailer mounted crank ups and pneumatic masts that go to 100' are 
mounted on trailers, but at that height they are guyed.  I can only 
guess at how one would install the "temporary" guy anchors.  Of course 
these are purpose built heavy duty trailers with truss outriggers, plus 
the guys.  I checked out a trailer mounted 100 footer at a surplus 
auction last fall.  A beautiful piece of engineering was reduced to 
scrap aluminum when a hoist cable failed.

Grant KZ1W


On 7/11/2013 6:44 PM, Eric Cary wrote:
> I have been talking with some friends about setting up a temporary tower on a trailer something like a boat trailer.
>
> Something like this:
>
> http://home.comcast.net/~k8cc/images/100_0137.JPG
>
> http://home.comcast.net/~k8cc/images/100_0816.JPG
>
> What is the highest you would go with a Rohn 25 or 45 tower with guys of course?
>
> 73, Eric N3TD "Touch Down!!!"
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