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[TowerTalk] Lift Mast to Replace Rotator

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Subject: [TowerTalk] Lift Mast to Replace Rotator
From: Keith Hanson <>
Date: Sun, 29 Dec 2019 19:21:50 +0000
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I have had a fair amount of experience swapping rotators.  At one point 
Hygain/MFJ had a pot problem; mine were wearing out in roughly a year.  What I 
did was procure a 2nd "hot swap" rotator so that I could do a replacement in a 
single tower climb.

I place my masts about 1/4" above the rotator bell so that when it is time to 
swap all I need to do is remove the bottom and clamp bolts and tip the HamIV 
out.  The new one is tipped into place, bolts connected and I am ready to go in 
 about an hour.

The key is to clamp the mast at the thrust bearing ( I used a muffler clamp) so 
that the weight of the mast and antennas is held off the rotator.  Once the new 
rotator is in place and clamped to the mast (with the 1/4" clearance) I loosen 
a set screw in the thrust bearing so that full weight of the mast/antenna is 
borne by the rotator.  I immediately retighten the thrust bearing .

When I first started this I used a home made two leg clamp to stabilize the 
mast in the tower, but I ultimately abandoned it because I could swap the 
rotators so quickly that I never had a problem with the mast tipping out of 

This was all with a 3el/40 SteppIR on a 10' Rohn mast.  I finally got sick of 
HamIV and put in a Yaesu 2800; I haven't had a problem in over 10 years now.  I 
still installed the mast on my 2800 with a 1/4" of clearance though.

Keith - AC9S

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