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[TowerTalk] Orion Mast clamp

To: "T talk" <>
Subject: [TowerTalk] Orion Mast clamp
From: "Dan Hearn" <>
Date: Thu, 11 Jan 2007 08:24:09 -0800
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Some time back I remember reading about a problem with slippage in the Orion
mast clamp. I believe it was on K7NV's web page. When Kurt speaks on
mechanical issues I listen. If it was somewhere else I apologize to Kurt. I
do not find it there now.
  The comment was that the Orion clamp has teeth on the inner surface to
grip the mast. The points of the teeth have very small contact area to the
mast. He suggested that one wrap a piece of emery paper around the mast with
abrasive side out and work the mast or clamp back and forth to dull these
teeth thus giving more contact area. Then remove the emery paper. Obviously
the problem is greatest when we are using the very hard chrome moly masts
since the teeth cannot penetrate the mast surface. The clamp is specified to
work with mast diameters 1 7/8 to 3 OD so it seems to me that the actual
contact area for any one mast size is not very great.
 I have 2 OR2800's in use here. One is used on a 2" mast with a F12 4BA. No
slippage there.
The other is used on a 2 7/8 chrome moly mast supporting a M2 6 el "Big
Stick" This antenna is very unbalanced for wind torque when supported at the
center of gravity and surges back and forth unless pointed directly into the
wind. The clamp did slip once this year after installation in 2001. The
bolts needed tightening and no problems since then.
  If I ever have the rotator down I plan to do the emery paper thing.

73, Dan, N5AR


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