TT:
Steve's correct (as usual.) The Trylon side mount shown will not allow
rotation of a center-mount HF Yagi.
Let me offer an alternative:
http://www.trylon.com/pdfs/Working%20platform.pdf . This is the work
platform for the Titan series of towers. Perhaps one could purchase (or
fabricate) two support angles for two consecutive tower sections and install
a top bearing plate and rotator plate on homemade platforms.
The issue with the Titan tower series is the taper - about three inches
of reduced face width in each section. The homemade platform would have the
center of the upper bearing offset from the tower face a few inches more
than the lower rotator plate. Also, this design (offset from a tower face)
will have a restriction on the azimuth angles through which the Yagi can be
rotated, compared with a design that has the axis of rotation off a tower
leg as shown in Steve's referenced web page.
With the work platform configuration a swinging gate type of rotating
assembly could be installed on the Trylons. But always keep the element
spacing in mind when you're designing the mount. And read the 2002 QST
article (issue?) about side-mounting large Yagis. And remember (last one, I
promise) - the Trylon Titan series is a light- to medium-duty design. I
wouldn't put too big a Yagi on it.
73 de
Gene Smar AD3F
-----Original Message-----
From: K7LXC@aol.com <K7LXC@aol.com>
To: spelunk.sueno@prodigy.net <spelunk.sueno@prodigy.net>; rich@n7tr.com
<rich@n7tr.com>; towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Sunday, January 05, 2003 12:16 PM
Subject: Re: [Towertalk] Side-Mount on Trylon T400-80?
>In a message dated 1/4/03 10:23:18 PM Pacific Standard Time,
>spelunk.sueno@prodigy.net writes:
>
>> Trylon's commercial web page lists such side-mounts:
>>
http://www.trylon.com/lightdutytowers/selfsupporttwrs_accessories.asp#side
>.
>
> Well, yes and no. This illustrates a sidemount that is mounted on the
>face of the tower. It's okay for a fixed sidemounted yagi but I think
Rich's
>question had to do with being able to rotate them.
>
> In order to rotate them, the sidemount needs to be installed so the
>sidemount/antenna is on the leg - not the face. Here's a drawing that
>illustrates the basic parameters - <A
>HREF="http://www.reprise.com/antronics/sidemount_clearance.asp";>
>http://www.reprise.com/antronics/sidemount_clearance.asp</A>. Without
knowing
>how much clearance is required (since Rich didn't say at what altitude and
>thus how much tower face you need to deal with) for where he was going to
>install an antenna or how much between-element clearance he'll need to do
any
>rotating, it's not easy to come up with a conclusive answer. I've heard of
a
>'stretch' design for the C31XR that adds some needed clearance between
>elements but this dimension becomes the crux parameter for any sidemounted
>yagi.
>
> It's easy to fabricate a sidemount and swinging-gate for any tower
>including the Trylon Titan - you just need some angle steel or aluminum,
some
>pipe, and some U-bolts.
>
> A good way to see what you need is to draw the proposed installation on
>some graph paper.
>
>Cheers,
>Steve K7LXC
>TOWER TECH -
>Professional tower services for commercial and amateur
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