[RFI] Noise emitted by rotator

Sun Aug 5 10:03:02 PDT 2012

I would try small ceramic filter caps at the rotor connector.  Just on the
power leads at first, then maybe to the shell ground to see what combination
stops the noise from getting out.

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: Bob Turner [mailto:Bob at n2scj.net] 
Sent: Sunday, August 05, 2012 16:23
To: K1TTT; 'Dale'; 'Pete Smith N4ZR'; rfi at contesting.com
Subject: Re: [RFI] Noise emitted by rotator

Any ideas how to filter the noise without opening up the rotor?  In other
words, rotor stays in tower.  My G-1000 is in a roof tower.  I can walk next
to it quite easily.  It's a major undertaking removing rotor from tower.  I
probably won't do that until it completely fails or something else goes
wrong with my antenna array.  I operate 2 meters up to 1296 on this array. 
HF reception is not an issue as no HF antennas are on it, and if I do
operate HF, I'm not using the rotor.

Bob

-----Original Message-----
From: K1TTT
Sent: Sunday, August 05, 2012 11:13 AM
To: 'Dale' ; 'Pete Smith N4ZR' ; rfi at contesting.com
Subject: Re: [RFI] Noise emitted by rotator

No pwm in there, just simple dc voltage control... it even has a 330uf
filter cap just before the direction switching relay.

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: Dale [mailto:svetanoff at earthlink.net]
Sent: Sunday, August 05, 2012 13:55
To: Pete Smith N4ZR; rfi at contesting.com
Subject: Re: [RFI] Noise emitted by rotator

Pete and All,

I have a G-1000 and can tell you that since it has a speed control, the
output of the control unit is PWM (pulse width modulated).  I have never
heard QRN from the rotor or control unit, but then again that rotator is on
my VHF/UHF tower.  I can tell you that even tho I have surge protectors on
the lines going to the rotor, something (rotor or controller)did not survive
a direct lightning hit to the tower's mast and some antennas.

My guess is that you were hearing some "hash" from the PWM circuits.  I did
experience some lock-up in very cold WX (under 10 deg F) due to stiffness of
the coax bundle going up to the antennas.  A few excursions of the direction
control would usually get things moving again.  Also, consider that the
sticking issue could be with the thrust bearing, rather than the rotator
itself.

73, Dale
WA9ENA

-----Original Message-----
>From: Pete Smith N4ZR <n4zr at contesting.com>
>Sent: Aug 5, 2012 6:58 AM
>To: rfi at contesting.com
>Subject: Re: [RFI] Noise emitted by rotator
>
>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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>
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