Troy,
With Andrews dishes, you can get away with smaller diameter pipe than spec'd or
other brands such as RadioWaves require. In several cases, This benefit was a
primary factor that led us to bypass our standard product line, in favor of a
radio brand that supported Anderws dishes, in order to meet a cosmetic, space,
or mounting challenge requirement.
It should be noted that from an engineering point of view, mounting to a narrow
tower leg (maybe 2-3", to a 4.5" diameter mast, to a dish, does not strengthen
windloading, as you are still limited to the strength of the weakest link which
is the connection to the narrower 2-3" tower leg, except because the antenna
offsets further away, the leverage is greater, making the force at the narrower
tower leg even worse. I challenge antenna manufactuer's decission to
standarize on 4.5" dia masts, but unfortuantely it is what they usually do.
With that said
A common acceptable practice is to use a short 4.5" dia mast in between the
tower and antenna, as described above. I highly recommend using galvanized
pipe. It can be found at Tessco or Special ordered from local metal/farming
supply stores such as "Standard Supply". Avoid non-galvanized pipe if you can.
It can be really expensive to ship 4.5" pole, which is why its a good idea to
try and find a local supply store. Choices are limited for galvanized
We buy the pole to pole mounts from Valemount Microflect or Tessco. Its
important to buy strong pole to pole mounts, that have significant surface area
on multiple points of the mast to prevent rotation. I will almost always use
more than 2 mounts between the tower and the 4.5" mast. Usually 3 will be
fine, but sometimes I'll double it up to 4, if the antenna is heavilly offset
to one side and resulting in mast tilt. Do not just rely on the stablizer bar
to prevent pivoting. Use good solid pole to pole mounts. Valemounts store
sitepro has a few models to choose from.
One type uses all-thread that passes through 4 v-shaped metal plates, secured
with nuts. This gives the advantage to vary the offset distance between tower
and mast.
This can be helpful to prevent antenna/mount parts from banging into the second
pole, when aligning. I highly recommend using nothing smaller than 5/8"
all-thread.
Obviously this requires a two mount kit, one for top one for bottom. But
doubling up each of the two mount points, increases a mount point from 2 to 4
allthreads, preventing a square that is stronger against twisting/slanting,
than just a single
The antenna will lock down super tight on the 4.5" mast. But you need to make
sure the 4.5" pipe doesn't pivot on the tower.
Usually the way it is installed is. The mast gets mounted to the tower
first, with two mounts on the bottom fastened. Then the 4 ft dish is raised
above the mount, and slid down onto the mast from the top. Then the top pole to
pole mount can be installed. After that is done then the stablizer bar is
installed.
If only mounting a 3" dish, if there is a 3" dia tower leg or wall mast, I'll
usually mount the antenna direct to the tower leg or wall mast, without using a
4.5" pole in between, its actually stronger that way, if its supportable or
jimmy riggable to do that. I know the Andrews 3ft are.
With 4' dishes, its worth following spec and using the 4.5" mast.
Andrews sells the stabilizer bar kits as a standard part number.
With that said...All Trango brand 3 and 4 foot dishes all come with stablizer
bars. If you ever get a chance to look at one, I suggest doing so. It
demonstrates a good design, on how it accommmodates mounting to different
positioned angles mount points. It probably could be replicated from hardware
store parts.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
- Original Message -----
From: Troy Settle
To: wireless@wispa.org
Sent: Wednesday, October 12, 2011 2:45 PM
Subject: [WISPA] Antenna Mounts
Can anyone point me to a specific antenna mounting kit for 3 and 4' Andrew
dishes? I've been advised to mount both on a 4" pipe directly on the tower,
but as this is my first construction project, I'm more than a little lost on
the specifics.
Of course the consultants and contractors on this project are being very
vague with their answers, and about the only thing I've heard from the vendor,
was a mention of "stabilizer bars."
Thanks,
-Troy
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