Originally Posted by Jesse Open

Age here is 69.4 B July 04, 1950

"73" is a telegrapher jargon used by old ham radio ops who still use Morse Code on the air. Also known as Continuous wave or "CW"

The numeric code is a small part of the abbreviations outlined in the Phillips Code (developed by telegrapher Walter P. Phillips). Like many other Morse Code abbreviations it has a certain "swing" or rhythm went sent. Dah Dah Di Di Dit Di Di Dit Dah Dah.
Instantly recognizable to Morse Code ops.



"The usage of "73" for such a purpose comes from the Phillips Code, originally devised in the era of telegraphs to speed up transmission of common messages by mapping them to numbers.

"73" mapped to "best regards" or "my compliments" and was intended as a general valediction for transmitted messages.

It is still used for that purpose today in morse code transmissions and often makes its way into everyday correspondence among hams as a form of jargon.

There is also "88" (which maps to "love and kisses") that sometimes takes the place of "73" for communications between affectionate parties."