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[TowerTalk] HDR-300 question

To: <>
Subject: [TowerTalk] HDR-300 question
From: (
Date: Mon, 24 Sep 2001 11:06:00 EDT
In a message dated 9/20/01 10:29:13 PM Central Daylight Time, writes:

<<  I installed a well-used HDR-300 last summer to turn a 5 el 20m Yagi (40ft
boom) and miscellaneous other smaller antennas on the same mast. The HDR-300
moves the stuff around quite well but there's 10-20 degrees of "play" in
direction when the brake is engaged.  Even in fairly light winds the
antennas always seem to be wiggling around.  Not a big deal on 20m but it's
a bit of a hassle with the 9WL 432 beam at the top of the mast...  Is this
"normal" for the HDR-300?  Any way to fix/improve it?

Fred, N9FH


Oh yes!  I have had a lot of painful experience with this!  The problem is 
the quality of the shaft and keyway(s).  I didn't realize until recently that 
there is an interior keyway which can also become elongated and cause this 
problem.  The exterior one is obviously also a potential problem.  The bad 
news is that it only gets worse--the antennas start really thrashing around 
and can cause them to slip on the mast (the quick stops) and/or shear off 
pinning bolts.

There is good news, but its not cheap or easy.

MFJ is totally set up to fix this and will do it cheerfully for approximately 
$265 which is what it cost me including freight.  They put in the harder 
steel shaft and better keys and, of course, generally service the unit.  When 
they do this, you get a vastly superior rotor which should be pretty trouble 
free.  Sadly, it's a huge job to remove the beast with the convaluted system 
of stradling the mounting plate they use, but this is the only answer.  Be 
sure and get MFJ to install the new quick-disconnect system for the control 
lines when they have the unit in house. 

Hopefully you picked this "well used" unit up reasonably, so when you add the 
cost of this repair, you still are way below the cost of any comprable load 

Good luck!

John Baumgarten, N0IJ
Duluth, MN

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