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[TowerTalk] OR-2800 replacement clamp for 2" mast.

To: <>
Subject: [TowerTalk] OR-2800 replacement clamp for 2" mast.
From: "Jim Thomson" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Wed, 3 Mar 2010 04:35:15 -0800
List-post: <">>
I see that Steve, K7LXC,   makes a replacement clamp for the OR-2800 rotor. 
Listed under Misc.. on his excellent website. 

Has anyone used these before ?   It appears the clamp  just bolts  to the
existing flat plate on the OR-2800  rotor.    My concern is, there appears to be
no adjustments like the stock clamp.   IE: the old clamp comes in from BOTH  

With Steve's clamp, it appears his retrofit clamp assy is designed for exactly 
a 2" OD
mast.  It appears to be welded across the bottom of the channel steel, so if 
the mast
is slid into place, the bottom of the mast  would hit the weld, and not end up  
with his  [what looks like 1/2" thick steel]  base plate ?   This may be a good 
allowing water to flow out the bottom of the mast. 

Another concern is, what about the stock   1/4-20 SS  bolt, that holds the 
stock base plate
to the internal rotor spline ??   The  stock set up has an option for a 'self 
centering mast'
which consisted of a triangle piece of 1/2"  thick AL.. with a longer  1/4-20 
SS  bolt. 

Either way, the 1/4-20 bolt is used to ensure the two splines stay mated 
With out it, the mast and the new clamp assy, is free  to  completely lift up, 
off the
rotor.  Perhaps the new massive  1/2" thick base plate has a recess on the 
to accommodate the  thickness  of the head of the 1/4-20 bolt ?? 

The stock OR-2800 clamp, has what appears to be a flat on either side, designed 
to accept a 3/8" G-5 or G-8  bolt... straight through both the clamp halves, AND
the mast between em.   IE:   "Pinning the mast"     The  OR-2800 manual warns 
NOT to pin the mast !   "just let it slip, or you will damage the rotor gears" 

Now if the stock clamp has no gripping power, and eventually slips, why not pin 
If Steve's  jumbo replacement clamp is used, [ with 6 x U-bolts/no saddles] , I 
doubt it
would slip either, it's the real deal.   So what's the real  difference ??  

On 2nd thought,  I think it would be VERY  difficult to precisely  drill a 3/8" 
 hole in 
from BOTH  sides of a 3/8"  thick, 106 ksi  chrome moly  mast ? 

Steve, what  does this clamp of yours weigh ??    Is it readily available ? 

Tnx... Jim   VE7RF  

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