[TowerTalk] OR2800 / RT21 cable type

[Jim Brown]

With both of the long runs to my Yaesu rotators, I use Romex for the 
motors and twisted pair for the direction sense, which is a tapped pot.

The importance of twisted pair for noise/RF rejection is not as well 
known by hams, but it's quite well known in the world of pro audio, 
where it's understood as just about as useful as shielding. All versions 
of CAT cables CAT5 and up, are four great twisted pairs, small gauge. 
Running those four pairs in parallel (as pairs) can work quite well if 
there's not much current. That is, connect all of the solid colors in 
parallel, connect all the striped conductors in parallel, and drive from 
solid to stripe.

In addition to having great interference rejection, it's a mass-market 
item, so we're more likely to find a good outdoor version of it cheap 
than other twisted pair cables.

For the Yaesu motors, it's all Ohm's law. Don't know about the Orion, 
except that I don't think I'd worry about interference rejection on the 
motor.

73, Jim K9YC

On 8/1/2024 5:40 AM, Paul N1BUG FN55mf wrote:
> I have an Orion OR2800DC and Green Heron RT21 both 3 years old. I have
> had pulse counting errors almost from the start. I know the cable is not
> in good condition as the resistance between conductors is only a few K
> ohms and is not consistent day to day. It used to simply miss counts and
> have to be recalibrated frequently. Slowing max rotation speed to 4
> helped a lot. Yesterday it started randomly seeing pulses when the
> rotator is not moving. This has quickly worsened to the point of being
> unusable. With the pulse counting wire removed from the RT21 it does not
> see any false pulses, so I think the controller is OK.
> 
> Assuming it is just worsening cable problems and not a rotator fault, I
> am hoping for a quick temporary fix using what I have on hand for cable.
> Can I use a run of coax for the pulse counting conductors? What effect,
> if any, would that have on the pulse train with a 350 foot run? I could
> use two runs of coax but I guess there would be no advantage since one
> of the pulse conductors is ground.
> 
> Thanks for any help or suggestions.
> 
> 73,
> Paul N1BUG
> 
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