Radar Antenna Alignment Procedures (DA-1203A)
Before proceeding, following these safety precautions.
- The aircraft’s power should be shut off 15 minutes prior to the alignment procedure.
- Confirm aircraft is level.
- Remove the vertical gyro (VG) and secure it on a tilt table so no movement occurs during testing. Both the tilt table and VG should be level and on the ground. Using an extender cable, connect the gyro to the aircraft.
- Turn on AC/DC power to the radar system and VG. Turn the radar indicator to STBY.
- Turn the tilt knob on the indicator to zero degrees. This should match zero degrees on the antenna. If not, the tilt knob may not be centered.
- There is a locking pin located just to the right of the main connector on the antenna. Remove the pin from the storage clips. With the antenna at zero degrees, insert this pin to lock the scan in place. The insertion point is on the right side of the antenna just below the tilt linkage. This will lock the scan at zero degrees.
- Pitch Adjustment: Pitch the gyro 10 degrees on the tilt table. The antenna should pitch 10 degrees. Using a protractor or digital level, measure the deflection of the antenna on the flatplate. If it does not measure 10 degrees, adjust the pitch potentiometer until 10 degrees is obtained. There is a labeled pitch adjustment on the antenna, just below the unit's ID tag. Adjust the pitch so the antenna deflects 10 degrees. Move the gyro in the opposite direction 10 degrees to make sure you have linear deflection. This completes the pitch adjustment. Return the gyro to zero degrees and remove the locking pin from the antenna.
- Roll Adjustment: Move the antenna to the right (opposite the unit's ID tag), to the 60 degree mark. There is another locking point for the pin to lock the scan into place. Once the scan is locked into place, physically turn the gyro 90 degrees on the tilt table (do not move the tilt table), then roll the gyro 30 degrees on the tilt table. Using a protractor or digital level, measure the deflection on the antenna flatplate. It should measure 26 degrees. If this is not correct, adjust the roll potentiometer until 26 degrees is obtained. The roll adjustment is located above the pitch adjustment just below the unit's ID tag. Roll the gyro 30 degrees in the opposite direction to make sure you have linear deflection. This completes the roll adjustment. Remove the locking pin from the antenna and install into the storage clips located to the right of the main connector.
- Turn off all the power and allow the gyro to spool down. Moving the vertical gyro while still running may cause damage to the bearings. Once the gyro has spooled down (approximately 15 minutes), reinstall the gyro into the aircraft.
Note: If linear deflection is not achieved during the alignment procedure, the antenna may not be mounted level.