Copper braid, especially if not tinned, corrodes in many exterior
environments and can suffer a loss of performance over time. Copper
strap of similar dimension is superior to braid in environmental survival.
Patrick NJ5G
On 10/17/2018 8:36 PM, Gary Smith wrote:
Folks,
Many replied off & online to help me out,
some went above and beyond in offering
their time and experience and thank you
for that, helping others is much of the
joy in our common bond.
To recap the issue: The RFI I have been
having is on 6M when the SPID rotated my
6M7JHV on the tripod on my ranch house.
The tripod is DC grounded by #4 solid
copper wire to the a grounding rod which
is bonded to the breaker panel and antenna
input/station ground. The noise was only
experienced when rotating, it was
determined NOT to be PWM in origin and a
360 rotation seen on my P3 SVGA display
looked like this and sounded as bad as you
would suspect.
http://doctorgary.net/spid.jpg
I have the problem now resolved to maybe
95% and I wanted to share this resolution
with you. Jeff at Green Heron has been
most helpful in being willing to work with
me as I bought the SPID RAK, GH controller
combo from him. Among the suggestions he
gave me was ferrite clamp on chokes on the
rotor control line and running a copper
braid between the mast ground and the
tripod.
I had an abundance of clamp-on ferrites
bought at the suggestion of Jim, K9YC a
few years back and placed around 10 on the
rotor cable starting at the SPID. I added
4-5 more to the coax attached to the boom,
just before the coax loop. The loop is
held in place by a clamp-on dacron roped
to the boom clamp. - I also took the braid
from 7' of 50 ohm coax, doubled it by
folding it in half, using Penatrox at each
connection, radiator clamped the fold/bend
to the mast, ran the two braids to the
grounding wire of the SPID. I screwed the
ground screw through the penatroxed braids
and then attached the two loose ends, now
penatroxed, to the tripod.
I don't know which of the three things
made the difference, I already had a few
clamp-ons added to the coax at the antenna
between the hardline and the loop but I
did add 2-3 more. But I did add those to
the rotor line and I did run that double
braid between the mast, the SPID ground
wire and the tripod. This is the result:
http://doctorgary.net/spid-rfi-fixed.jpg
This photo was taken after the exact same
360 degree rotation & same frequency I
showed in the earlier photo showing the
tremendous RFI.
So to those who have this issue, you might
want to do as Jeff suggested and what I
followed through with, obviously, it is a
solution that works beautifully.
Hope this helps someone.
73,
Gary
KA1J
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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