Stan Griffiths wrote:
> >In a message dated 98-04-12 16:41:28 EDT, gwolf@gte.net writes:.
> >
> >> Can one put a Ham IV rotator in Rohn 25 ? I'm asking whether it can be
> >> put
> >> in a non top sections w/o any alterations to the section.
> >
> > Yes, the Ham IV will fit in 25G. You can squeeze it through the braces
> >with the proper application of huffing, puffing and liberal use of American
> >colloquialisms.
> >
> > The question really, though, is where can you fit the AS25G Accessory
> >Shelf/rotator shelf. It will only fit at tower sections junctions or in the
> >open faces of tapered top sections or BAS25G Bearing/Accesssory Shelf.
> >
> > I think W7NI had a scheme/design for a modified AS way to mount the
> >rotator anywhere in the section. An update, Stan?
> >
> >Cheers, Steve K7LXC
>
> As Steve says, the Ham IV will fit in a Rohn 25G section, but once you get
> it in there, it will not slide freely up and down the tower. The bell
> housing is too large to get past the horizontal braces and it will hit the
> diagonal braces as it rotates except in a very specific narrow range of
> vertical positions. So you have to mount it exactly right.
>
> I made a sample shelf out of plywood just to see if I mounted it on top of a
> set of horizontal braces, the Ham IV could sit on this shelf and rotate
> freely, missing the diagonals. It looks like it can. One COULD make such a
> shelf out of steel plate and mount it to the horizontal braces with small
> u-bolts (1/4" cable clamps). It might not be a good idea, however, since
> all the torsion applied to the rotator by the mast would be transmitted to
> the shelf and then to the horizontal braces and then to the welds that hold
> the horizontals to the tower legs. The main question is: Can those welds
> stand up under this type of stress? I don't know the answer to that question.
>
> I am still thinking of making a real steel shelf like this and installing it
> on one of my towers. The next question is: How long does it have to stay
> there without a problem before we believe it is a good idea? The REAL way
> to answer that question is to engineer the project and calculate all the
> stresses and know how strong the welds and horizontal braces are in this
> type of service. This is a job for a REAL PE, which I am not . . . So the
> only approach I can take is to build one, put it up, and wait. Not really a
> very good approach but I don't see another choice for me.
>
> You know, if you took a standard AS25G, rotated it inside the tower 60
> degrees, and bolted it to a set of horizontal braces with 1/4" cable clamps
> used as u-bolts (discard the saddle), you could try this experiment
> yourself. You might have to shim the plate where it rests on the horizontal
> braces of the tower section so it is perfectly parallel with the bottom
> surface of the rotator.
>
> Try this at your own risk, but let us know how it works out, OK?
>
> Stan w7ni@teleport.com
>
> --
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
> Search: http://www.contesting.com/km9p/search
Hi guys, I have a rotator plate available that will fit almost anywhere in
Rohn
25 sections.
It is attached to the legs.
$45.00 plus shipping
73,
Bob WA1ZJE
--
TOWER ACCESSORIES
Rotator plate fits almost anywhere in tower section
Custom antenna mounts made to order etc.
Bob Feltmate WA1ZJE Member of: ARRL, AMSAT, NARC, NEWS
PO Box 21
Norton, MA. 02766-0021 FN41jx
E-mail: wa1zje@ici.net
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|