500 kHz
MARITIME RADIO FREQUENCY AT 500 KHZ
500 KHz; 500 kc; 600 meter band; 500kHz; 600m band; Auto alarm
The radio frequency of 500 kilohertz (500 kHz) had been an international calling and distress frequency for Morse code maritime communication since early in the 20th century. For most of its history, this international distress frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles (per second) or 500 kc.