Pine Research MSR 636A, User Manual, Page: 102 / 176

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6.6 Rotation Rate Calibration
The rotation rate is controlled by a tunable analog feedback circuit located inside
the control unit. This circuit is tuned and calibrated at the factory prior to
shipment, but if the rotator needs to be recalibrated by the owner at a later date,
the procedure below describes the best method for calibrating and verifying the
rotation rate control circuit.
The most important tool required for calibrating the rotator is a non-contact
optical tachometer . Pine offers such a simple tachometer (see Figure 6.1) as part
of the MSR Calibration Kit, and this simple tachometer is suitable for routine
verification or calibration of the rotation rate by the owner. The MSR Calibration
Kit is sold separately (see Section 7.1 for part number).
In the event that the rotation rate must be rigorously traceable to a national or
international standards organization, a more sophisticated and professional
tachometer with traceable certification should be used (see Figure 6.2). When a
rotator is manufactured at the factory (or when a rotator is returned to the factory
for service), recalibration is performed using a traceable tachometer.
The tachometer reads the rotation rate when it is pointed at a rotating shaft
equipped with a
reflective target (see Figure 6.3). The MSR Calibration Kit includes
a shaft suitable for use as a target. Alternately, a stainless steel
rod (1/4" OD x 5" L; 6.35 mm OD x 100 mm L) may be mounted in the motor
coupling, and a mark can be made on the rod with a marker.
The calibration process involves making adjustments to various trimmer
potentiometers (trimmers) on the circuit board. The MSR Calibration Kit includes
a
trimmer adjustment tool for this purpose. Alternately, a small flathead
screwdriver can be used to make these adjustments.
A calibrated digital voltmeter is required to confirm certain signal levels on the
circuit board. It is recommended that a 4 ½ digit voltmeter be used for this
purpose. The calibration process also requires a
known voltage source (1000 mV).
This known source can be a power supply or waveform generator, and the value
of the known voltage (1000 mV) should be verified using the calibrated digital
voltmeter.
Other tools required are a medium sized Phillips screwdriver (to remove the top
panel of the control unit) and a small (5/64") hex key (to turn the hex screws on
the motor coupling when installing or removing a shaft). The hex key is included
with the purchase of a new rotator and it is also available at many retail hardware
supply stores.