[RFI] Noise emitted by rotator

[Pete Smith N4ZR]

Thanks to everyone for their ideas on this.  I had come to pretty much 
the same conclusion as Dave about the filter, maybe with some support as 
well for the idea that the brushes in the motor are wearing out.  Then I 
decided to test the theory that it had something to do with disuse, 
since I hadn't turned the antenna in a week or so.  I started it 
rotating clockwise and after about 90 degrees the noise suddenly 
stopped.  Turned back and forth a few more times - no more noise.  I'm a 
happy camper, because I wasn't looking forward to climbing the tower to 
deal with it.  I'm sure it may come back, and eventually I'll have to 
deal with it, but for the moment.....

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

On 8/5/2012 6:35 AM, K1TTT wrote:
> 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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