On an Orion, two wires are used for DC to drive the motor. The DC is
reversible to reverse direction.
Two wires are used to carry pulses from a reed switch activated by a
magnet on the rotator motor shaft.
These pulses are a notorious source of noise when the rotator is in motion.
M2 recommends shielded cable, i.e. RG-58 to suppress that noise.
Googling around will find several references to this and various solutions.
Les W2LK
Jim Brown wrote:
> On Thu, 22 Apr 2010 04:28:58 +0000, k2wd@comcast.net wrote:
>
>
>> Anyone know where I can find suitable rotor cable for the OR2800 rotor (2x
>> 12ga, 2x 18ga shielded pair).
>>
>
> 3x#12 is very common house wiring (phase, neutral, and a ground). Shielded
> twisted pair is quite common in the pro audio world. BUT -- take a careful
> look at what the circuit is doing. Is the shield ONLY a shield, or is it
> also an active conductor? Very common usually means very inexpensive.
>
> We have learned in the pro audio world that a foil/drain shield on twisted
> pair has terrible RFI properties. On the other hand, an unshielded twisted
> pair has very good rejection of noise and RFI.
>
> I suggest that you study the rotor control to see exactly what those cables
> are connecting. In my Yaesu rotor, one pair runs a DC motor, and three
> conductors monitor the position of a rotary pot that indicates rotor
> position. I have a long run between rotor and shack, so I used two 250 ft
> runs of 3-conductor house wire from the shack to the tower, and a 130 ft
> run of nicer cable that I found at a surplus house to run up the tower. It
> works quite well.
>
> 73,
>
> Jim K9YC
>
>
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