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[TowerTalk] Rotor Reconditioning Preference?

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Subject: [TowerTalk] Rotor Reconditioning Preference?
From: (James Wolf)
Date: Fri, 12 Jun 1998 11:52:09 -0500

> I am looking at buying a used Hygain HDR-300 rotor.  It looks clean but has
> not been serviced since coming down off the tower.
> I have found two sites on the Internet for rotor service, Norm's Rotor
> Service  and The Rotor Doctor 
>  .  Any experiences that would recommend
> one over the other (quality and price) to recondition the HDR-300?  BTW: 
> The seller is asking $400., is that a reasonable price for this rotor and
> control even if I have to pay $100. plus to get the rotor reconditioned? 
> Thanks & 73, DavidC  AA1FA


I have an HDR-300 Rotor that is about 8 years old.  The problems I have had 
are related to the torque of what it is trying to hold.  The failure points are 
1. The key that holds the platform to the main shaft and 
2. The key that holds the main shaft to the large gear internal to the rotor. 

These points must be tight with absolutely NO slop.  If there is any slop the 
platform and possibly the main shaft  and the large internal gear will 
eventually have to be replaced.  Even if the key is replaced, it most likely 
means that there is some wear/damage to the key slot in the main gear. 

I am turning a TH6DXX and a Cushcraft 40-2CD,2 el 40 along with a couple 
of VHF beams.  The rotor is about 40 ft below the top of the tower where 2" 
pipe between the rotor and the first antenna absorbs the shock of the twist.  

This combination will not hold up to the keys/platform/gear restraints.   What 
I ended up doing, is actually braising the main shaft internally to the large 
gear.  If you do this, it needs to be done by someone who knows what they 
are doing or you will loose the shaft and the gear.  They sit on a bearing 
surface that must be perserved.  I also bought a Q-lock and braised the 
platform onto it.  The Q-lock ( I think that is what it is called ) has a key 
fits where the platform normally would sit. This needs to be removeable in 
order for you to be able to remove it from the rotor plate.

The platform is then braised to the top of the Q-lock.  The Q-lock when 
installed actually compresses itself onto the main shaft which prevents 
movement and preserves the Key.

This method has held for the last 6 years. In the previous two years I 
relplaced the platform twice with many keys, I also replaced the main shaft 
which HY-Gain graciouslyl replaced free with their new version that is made 
from, I think, Stainless steel or some alloy thereof.

Internally the large gear looks indestructable and I have only heard of one 
failure case where it broke on a 3 el full size 80 meter beam.

I am not suggesting a path for you to take, just my experience.

Best of luck,

James Wolf, KR9U (home) (work)
FAX (219) 637-7074

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