[RFI] Noise emitted by rotator

Sun Aug 5 03:35:30 PDT 2012

There are 2 things to consider in this... in that rotor the motor is
actually isolated from ground, and it contains a filter circuit consisting
of chokes and capacitors.  One of the first odd things I helped diagnose was
a case where the filter was damaged in such a way that it had a low
resistance to ground on one side.  The odd result of this was that the rotor
turned slower one way than the other because the ground reference for the
speed control is through a resistor to ground and when the motor circuit
isn't isolated the ground reference changes when you power the motor.  So if
a motor for one of this series starts making noise I would suspect the
filter circuit is damaged or that something in the circuit is leaking to
ground which would make the tower the radiator.  Check the resistance of the
motor leads to ground, it should be essentially an open circuit.  If that is
ok you might be able to add capacitance at the connector up on the tower to
improve the filtering.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net

-----Original Message-----
From: Pete Smith N4ZR [mailto:n4zr at contesting.com] 
Sent: Sunday, August 05, 2012 01:33
To: RFI List
Subject: [RFI] Noise emitted by rotator

I've started noticing that on 10 meters my top Yaesu G-1000 rotator has
begun to emit broadband white noise when the antenna is actually turning.
Any ideas what the cause could be?

73, Pete N4ZR
The World Contest Station Database, at www.conteststations.com The Reverse
Beacon Network at http://reversebeacon.net, blog at
reversebeacon.blogspot.com, spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000

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