[amsat-bb] Azimuth Elevatioin revisited

["Dave Lamont" <lamontd@xxxxxxxxxxxx>]

Hi ALL,

Seems there is a demand by the size of the mail this morning.

Maybe somebody could send me the general details of the
"light weight" general purpose rotators so that I can be more
specific????.

A FAQ response to rotator interfacing.


The requirements to interface rotators other than the Yaesu
G-xxxx series is set out below.


1: The rotator MUST have three wires available from an internal
   potentiometer which has a value between 100 and a 1000 ohms.
   The preferred value is 500 ohms wire wound. The potentiometer
   will be geared to the rotator training mechanism and if a 
   source of 5 Vdc, provided from the "controller card", is applied
   to the outside legs of the potentiometer, the center leg 
   will present a DC voltage representing the angular position
   of the rotator. It is this voltage that is conditioned and
   sent to an A/D on the UNI_TRAC card via  the "controller card" 

2: The motor driving the rotator gearing should be a low
   AC voltage, split phase device. This arrangement is
   normally drawn in a schematic diagram as a center tapped
   motor winding with a non polarised 100 uFd capacitor, or so,
   across the outside ends of the winding. The AC voltage seems
   to range from 20 to 30 Vac normally.
   
   The transformer supplying the low voltage AC has one leg
   connected to the center tap of the motor winding. The other
   transformer leg is connected via switches, (in this case triacs)
   to either of the motor winding outside ends.
   
3: The transformer suppling the low voltage AC for the rotator
   motor should as well provide a source of 9 to 15 Vac for
   the bridge rectifier on the "controller card."
   
      
4: Other methods of interfacing the motor drive can be achieved
   directly off the UNI_TRAC card from its open collector outputs
   and suitable external custom interfaces. However some means 
   of conditioning and calibration control MUST be applied to
   the analog voltage fed back from the rotator's potentiometer.

5: The controller card shown in my web site was designed for
   low AC voltage service. However PROVIDED EXTREME CAUTION is
   observed when working with the controller, the controller
   is capable of switching full mains voltage taking the triac's
   maximum current rating into consideration.



Regards

Dave Lamont
   ZL2AMD
  http://www.qsl.net/zl2amd/
  lamontd@clear.net.nz

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