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Re: [TowerTalk] TowerTalk Digest, Vol 119, Issue 6

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Subject: Re: [TowerTalk] TowerTalk Digest, Vol 119, Issue 6
From: "James Wolf" <>
Date: Sun, 4 Nov 2012 12:39:11 -0500
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There is also the problem with the HDR-300 where the platform is held to the
main shaft with a 1/4" key.  That key also is a weak spot.  What we did was
to braze a (I think it was called) a Q-lock with a 1/4 " key to the bottom
the platform.  Not using the key at all in the original bottom platform -
the Q-lock will tighten very tight against the rotor main shaft and mitigate
the back and forth rocking  and rounding out the key and damaging the shaft,
which is the issue with the original.   I also brazed the main gear to the
main shaft.  This configuration has been up and working for over 20 years
with a 2 Element 40 and a TH-6 along with a stack of long 2 meter antennas.
I have not had a problem with the wind moving the break, but that is a
friction assembly, which can be replaced very easy.

Jim, KR9U 

>>The first thing you do with a HDR-300 is remove the stops.  If it rotates
past the stops, things break.  By pass or remove the stops.
The HDR-300 does not have a wedge break like the Ham or Tailtwister.
The shaft keyways in the HDR-300 are poorly designed resulting in worn
keyways with lot of play.  Unless you braze the shaft to the large gear or
redesign the shaft keyways, it will end with a lot of play which will get
worse and worse as the keyway wears.
One does not need to raise the mast to remove a HDR-300, and generally with
a Ham/Tailtwister.  Just leave say half inch gap between the mast end and
the rotor end.
BTW HDR-300 with ac motor do not work as well as other dc motors when used
with a Green Heron controller.
An Alfa Spid is a good rotor.


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