[TowerTalk] Alpa SPID RAK motor noise

[john at kk9a.com]

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