All stations transmit continuously during the time required for calibration with keyed tone modulated carrier (H2A emission), except where noted, and have a reliable range of 5 miles. Their assigned characteristic is transmitted twice followed by a 20-second dash, the complete sequence being repeated twice per minute. The antenna is located on the light structure. In the event special calibration service interferes with the operation of regular radiobeacon transmissions, the special calibration service will not be given.

Special calibration operation will be made only upon request in advance to the district commander in whose district the calibration station is located. The address and district limits of which are listed on p. iii (of light list). The day, time, and frequency on which special calibration service is desired must be stated. If service is desired on both frequencies listed, the time that transmission on each frequency is desired must be specified. Upon arrival at the station on the date and hour specified, station personnel may be contacted by means of the usual whistle signal or flag hoist.