Hi Steve,
If I had my druthers, I would replace the 25G with 45G, but this is not to be.
The
installation is at a club station (inherited system). Guess it likes to eat
T2X's.
Haven't been able to get a quantified answer from anyone on the reflector as to
whether or not 25G is up to the job. A few worried groans, but no numbers. Side
load
and oveturning calculations say - yes the installation has positive margin up
to 110
MPH, but nobody seems to know how to calculate for torque capacity.
Post mortem on the current installation indicates that the tower will survive
if the
rotator is put in correctly (we lost some Z bracing welds near the rotator, but
this
appears to be due to the way the rotator was attached).
Mike, W4EF.........................
-----Original Message-----
From: Steve Jackson [SMTP:stjackso@nortelnetworks.com]
Sent: Thursday, May 06, 1999 7:01 AM
To: Michael Tope
Subject: Re: [TowerTalk] Mounting the OR-2800 in Rohn 25?
Mike
Random evil thought, but if a beam is big enough for an OR2800 rotor, is
25G big enough for the beam?
Steve KZ1X/4
(OR2800 & 55G)
* * *
At 10:31 AM 5/5/99 -0700, you wrote:
>
>
>I am trying to figure out how in the heck to get an M2 Orion 2800
"positioner" into
>Rohn 25. The 2800 has a triangular cross section which lends itself to fit
inside a
>"rungless" portion of 25G such as found in the various types of 25G top
sections.
>Unfortunately, I would like to place the rotator well below the top of the
tower (10 -
>12 feet) to minimize the lever arm effect of the long mast outside the
tower working
>against a short piece inside the tower.
>
>One option appears to be to utilize the gaps in the Z-bracing created by
the section
>junctions. In this case, the AS25G rotator plate would be mounted just
below the
>section junction junction (immediately above the highest set of horizontal
rungs on
>the section below the joint).
>
>Since the gap created by section joint isn't quite big enough to
accomodate the
>rotator, I would either have to cut the horizontal rungs just above the
junction
>(lowest set of horizontal rungs on the section above the junction), or
somehow
>increase the spacing between two sections using somekind of spacer tubes.
>An extra six inches (plus overlap) of straight tubes with no bracing would
create
>more than enough room for the rotator, and would make servicing very easy.
>
>Does anyone know if Rohn makes spacers like that I could use to open a gap
in
>the bracing, or should I sharpen my hacksaw? This spacers would need to be
a six
>to eight inch piece of 25G leg material with a standard Rohn 25 swage on
one end,
>no taper on the other, and holes for 25G leg bolts on each end.
>
>Thanks again.
>
>Mike, W4EF.................
>
>
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