Usually near the end of an amateur radio conversation (QSO) the phrase “seven three” or “seventy three” will be heard. New hams or unlicensed listeners will probably wonder, 73 what? Here is more of that ham-speak stuff we are learning about and this terminology has a very particular meaning.
73 simply means, “Best Regards”. It is a very common phrase used on the radio in voice, Morse code (CW), and data communication modes and is often used in emails and handwritten notes between hams. 73 is considered a polite and friendly way of signing off all forms of communications between hams or as a general show of respect.
The origins of 73 are not absolutely certain, but the prevailing idea that it is a remnant of 1870s American telegraph codes is supported by historical documents. We find a long list of numeric codes that represent common phrases that would be sent in telegraphy. This saved the operators time by simply sending a one- or two-digit code instead. Because early amateur radio was Morse code work, hams adopted some of the telegraphy practices and codes. 73 is one of the few codes that have survived a hundred years of ham radio history, along with judiciously-used 88 (Love and Kisses).
For a fun and interesting look at origins of 73, a great reference for this and many other obscure ham things is found at the Origins of Hamspeak site by AC6V. One legend holds that 73 derives from respecting someone so much that you would pass along your valued 1873 Winchester rifle to them. Hogwash, but fun to read. That site is also referenced in our Links page under Origins of Ham Things.
73 is particularly meaningful in CW mode where the Morse characters form a palindrome (reads the same backwards and forwards). 7 is dah-dah-dit-dit-dit and 3 is dit-dit-dit-dah-dah. So 73 is sent dah-dah-dit-dit-dit dit-dit-dit-dah-dah. When CW hams hear this they don’t think of a number; instead they know that the other guy is sending his regards and wrapping up a QSO.
By the way, 73 is a singular code so the plural form doesn’t make sense. You would not write, “Best Regards’s”, so proper usage is not 73s, it is simply 73.
73, Jim Peisker AF5NP