[TowerTalk] Mast slipping

Greg ab7r at cablespeed.com
Fri Apr 20 21:51:06 EDT 2007


Thanks for this post.  I just installed an Optibeam OB12-6 on an Orion 2800
rotor.  A couple days later we had a small wind storm and it did fine.  But
we do get some nasty ones here on Whidbey Island too.  I meant to call M2
and ask about pinning and to side tracked today.  So it seems pinning this
should be fine.  I used a 2-in aluminum mast with 1/4 wall.  I know thats on
the light side but I only mounted the antenna about 8 inches above the
thrust bearing.

Tnx
Greg
AB7R


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of Byron
Lichtenwalner
Sent: Friday, April 20, 2007 6:27 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Mast slipping


I am in the process of replacing my current rotor with a 2800.  I have a
Steppir MonstIR on a 2" mast.
In the attached note Steve suggests pinning the 2800 mast clamps for
everything EXCEPT the antenna I have.

What would you suggest for the MonstIR ?

Byron, W3WKR

In a message dated 4/17/2007 7:24:54 P.M. Pacific Daylight Time,
cmsande at gmail.com writes:

>  I saw some old posts by you (circa 2002) stating that you have  started
pinning the Orion rotators due to slippage.  I have a Orion  RC2800PX
turning a
4L SteppIR and each time we have some wind, by antenna gets  swung out of
position.  This happened again today.

Hiya, Craig --

    It's an Orion design flaw, the mast clamp has 2  problems. First, the
surface where the nuts and bolts seat are dimpled - not  flat. Over time,
the
wind motion causes the washers to pound the dimples flat,  thus loosening up

the
nuts; then the mast is loose and starts moving. The  problem can be
eliminated
by milling or grinding those surfaces flat.

    Secondly only 2-3 teeth of the clamp actually  contact the mast,
resulting in very little clamping. Then you get the teeth  being worn down
as
the mast
moves back and forth and it loosens some more.

You can re-tighten everything and it'll probably  be good for a couple of
years. For a 4L SteppIR, you can also pin the mast.  Pinning works for
everything
except a MonstIR.


>  I have heard good things about the Green Heron Engineering  univeral
rotator controller, which can be re-calibrated in case the mast slips  in
the
rotator, however eventually the coaxial cable loop would start wrapping
around
the
mast if I did nothing more to secure the rotator-to-mast  connection.

    The GH controller is very nice but won't do  anything about the basic
problem.


    What I do for my customers is provide a new  replacement mast clamp that

uses 6 U-bolts to hold the mast and does NOT slip.  It's $120.00 but if you
re-tighten everything and pin the mast, you'll be good  to go.

Cheers,
Steve      K7LXC
Champion Radio Products
Cell: 206-890-4188





_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk



More information about the TowerTalk mailing list