[TowerTalk] Alpa SPID RAK motor noise

[Gary Smith]

There are four wires to the rotator; two 
for DC and two for control. There are 
small disc caps attached to each of the 
control lines with a common wire to ground 
which is screwed to the protective cover. 
There are no caps I can see related to the 
power side. There's a resistor in series 
with the + line but that's not going to 
help in this regard.

http://doctorgary.net/spid-caps.jpg

The black wire hanging down terminates in 
a brass eye terminal that is screwed down 
to the cover, this anchors to the metal 
case providing the ground.

Gary
KA1J

> Inside all of my TIC Ring rotators are filters connected to the wiper
> motors. Perhaps a filter can be added at the Alpha SPID RAK motor to
> reduce the hash.
> 
> John KK9A
> 
> 
> From:	"Gary Smith" <Gary at ka1j.com>
> 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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