SK (End of Contact) in Morse Code
...-.-
Dot-dot-dot-dash-dot-dash: ···—·— . Like every other prosign, SK is sent as one continuous signal rather than as two separate letters, and its procedural meaning is simple — end of contact, the entire exchange between two stations is finished, not just the current message.
Not the Same as AR
SK is easy to confuse with AR, another common prosign, but they mark genuinely different things: AR signals the end of a single message while more traffic may still follow, while SK signals that the whole conversation is over and neither station expects to hear from the other again in this session. Getting the two mixed up in formal traffic can leave a receiving operator unsure whether to keep listening, which is exactly the ambiguity the two distinct prosigns exist to prevent.
Where "Silent Key" Comes From
SK has a second, entirely different meaning inside amateur radio culture that has nothing to do with ending a routine transmission: "Silent Key," the term hams use to refer to an operator who has died. The phrase traces directly back to the physical telegraph key — when an operator passed away, their key would fall permanently silent, and early amateur radio operators, working almost exclusively in Morse code in the hobby's earliest decades, adopted "Silent Key" as a term of respect for a departed CW operator whose key would never sound again. The double meaning lines up almost too neatly: the same two letters that mean "this transmission has ended" became the phrase used when an operator's transmissions have ended permanently.
A Tradition That Outlasted Morse-Only Radio
Amateur radio has long since expanded well beyond Morse code into voice, digital modes, and video, but "Silent Key" never faded out along with CW's dominance of the hobby. It's still the standard term used in club newsletters, memorial listings, and obituaries across the amateur radio world today, including in the American Radio Relay League's monthly QST magazine, which regularly publishes lists of Silent Keys reported to it — a small piece of Morse code procedure that quietly became a permanent part of the hobby's shared vocabulary, used by operators who may never have sent a word of actual Morse in their lives.
Frequently Asked Questions
What does the Morse prosign SK mean?
It marks the true close of a contact — the point where both operators agree there's nothing more coming and it's safe to leave the frequency, unlike AR, which only closes a single message with more likely still to follow.
Why is a deceased ham radio operator called a 'Silent Key'?
The term comes directly from the Morse prosign SK, meaning end of contact, combined with the literal fact that a deceased operator's physical telegraph key would fall permanently silent — early amateur radio operators adopted it as a term of respect.
Is 'Silent Key' still used even by hams who don't use Morse code?
Yes, and increasingly by people who've never sent a word of actual Morse — the phrase has become inherited vocabulary the way sailors still say "mayday" without knowing it comes from French, showing up in obituaries for operators whose entire radio career was voice and digital modes.