Which step must be taken when turning on low drive?

The step of calling UPD to confirm activity on the roof is crucial for safety and operational awareness when turning on low drive. Before engaging low drive, it's important to ensure that there are no personnel or equipment on the roof that could be endangered by the increase in power or changes to equipment behavior. Confirming activity helps to prevent accidents and ensures that the transmission process proceeds smoothly without unexpected interruptions or hazards.

This precaution reflects sound operational protocol in radio station management, highlighting the importance of communication and verification of personnel safety when conducting technical procedures. Keeping an emphasis on safety aligns with the best practices in broadcasting, where the protection of equipment and staff is paramount during any operational changes.