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Re: [TowerTalk] TB3 Thrust Bearing Binding

Subject: Re: [TowerTalk] TB3 Thrust Bearing Binding
From: TexasRF--- via TowerTalk <>
Date: Thu, 30 Jul 2015 17:30:42 -0400
List-post: <">>
Hi Ken, an often overlooked problem with the T2X and HAM series rotator is  
a defective phase shift capacitor. When these capacitors age, and heat 
helps do  that, they become lossy and the rotator looses power.
This capacitor is a large non polarized electrolytic unit located inside  
the control box. For a test, you can substitute a capacitor intended for use 
as  a starting capacitor in 120/240 vac motors.
Gerald Williamson K5GW
GM Texas Towers
In a message dated 7/30/2015 4:14:17 P.M. Central Daylight Time, writes:

>From all  indications with the outside temps reaching 100 degrees F, one or
both of  my two TB3 thrust bearings seems to be binding.  All TX2  
rotator electrical data measured from the ground matches my  baseline
(resistance), I can hear and feel the brake release and the  voltages 
to the TX2 motor windings are normal but until this  morning when it got 
the 80's - it wouldn't budge at all.  I use  one thrust bearing on the top
platform and a second as a means to remove  the rotator if ever needed and
keep the tangential loads off of the TX2  rotator.  I believe this happened
the day before and it was in the  same position (332 degrees).  Usually when
the 40 meter beam fails to  rotate, the TX2 brake mechanism is binding even
with the Green Heron RT-21  rotation algorithm (small rotation the wrong way
before rotation to the  commanded setting).  Is heat a feasible failure
mechanism for a Rohn  TB3?   Anybody else ever run into this problem?   Ken


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