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Re: [TowerTalk] Alpa SPID RAK motor noise

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Alpa SPID RAK motor noise
From: <john@kk9a.com>
Date: Thu, 11 Oct 2018 20:00:10 -0400
List-post: <mailto:towertalk@contesting.com>
I have a number of Green Heron controllers. In the room I can hear the
little squealing sound when the controllers ramp. When using a single radio
I do not hear this sound in my headphone audio but I did when running SO2R.
This occurred when I used a DX Doubler years ago and also when I switched to
the MicroHAM Micro2R SO2R controller. I improved my station bonding and the
ramp noise in the headphones continued whenever I used two radios. Jeff
offered a lot a lot of suggestions but this was never a high priority on my
fixit list so the problem went on for years. One day I discovered that the
headphone SO2R cables that came with my Top Ten DX Doubler were not shielded
and I had used these same cables with the Micro2R since MicroHAM does not
supply any with this device. When I made new cables using shielded wire the
noise disappeared. So, check your bonding and your shields. I did not try
the motor caps that Dave suggested but I do have ferrits on all of the
control cables entering the shack. 

John KK9A


From:   "David Robbins" K1TTT
Date:   Thu, 11 Oct 2018 20:13:25 -0000

To test you can turn off the ramp up/down function in the gh controller.  It

does make noise, but the noise is only there during the ramp periods, it is 
pure dc when it gets to full speed.  I think I have two .01uf caps at the 
controller between pins 1&2 which gets rid of most of it. 
 


From:   "Gary Smith" KA1J
Date:   Thu, 11 Oct 2018 01:39:41 -0400

I have motor noise when I rotate the new 
SPID RAK & I've held off asking here till 
I completed properly grounding the house, 
coax & rotor lines. Unfortunately it 
hasn't helped the issue I'm having with 
the rotor and maybe someone has a 
suggestion of something I can try.

The antenna is a 6M7JHV, it is on a tripod 
mounted in the center of the house. There 
is a #4 Gauge wire attached to the tripod 
which goes to an 8' ground rod. This 
ground rod is connected with #4 solid 
copper to the breaker box and the ground 
rod with the Polyphasers which goes to the 
shack, the ground to the shack attaches to 
this last ground rod. There are 3 
additional ground rods attached to the #4 
wire.

When I turn the antenna it obliterates the 
waterfall and raises the meter 7 S units. 
As soon as the motor stops all is well. 
The controller is a GH RT-21D. The 
tailtwister it replaced never left any 
indication it was turning other than the 
meter. 

It was suggested it is because it is a DC 
motor in the SPID and the noise is likely 
coming from the brushes. Also that the #4 
to ground is not a RF ground and if it 
were attached to a tower instead of a 
tripod I likely wouldn't have this issue. 
The possibility was raised of the brushes 
having an issue or perhaps the two caps 
attached to the control lines to ground 
may be a problem.

Here is a photo of the SVGA output from 
the K3.
http://doctorgary.net/spid.jpg

I started at 180 deg and rotated clockwise 
to 179 deg. The dark red is at 240-290 
degrees, the two strips of blue where 
there is no interference happens around 
340 and 80 degrees respectively.

I've never read of anyone having this 
problem before, guess I'm the lucky guy. 

Any suggestions I might try?

Thanks & 73,

Gary
KA1J


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