Morse Code Prosigns & Procedural Signals
The shorthand CW operators use to control a conversation — every major prosign, its exact code, and what it actually means on the air.
If you’ve ever read a real Morse code (CW) exchange between ham radio operators, you’ve probably seen strings like AR, SK, or KN tacked onto the end of a transmission. These aren’t abbreviations for words — they’re prosigns (procedural signals), a small set of merged letter-codes that function like punctuation and traffic control for a conversation sent entirely in dots and dashes. Prosigns tell the other operator when to reply, when to wait, when a message is finished, and when the whole contact is over.
This page covers the prosigns you’ll actually encounter on the air, in order of how often you’ll use them — a natural companion to our full guide on Morse code for ham radio (CW).
What Is a Prosign, Exactly?
A prosign is formed by taking two (occasionally more) plain letters and sending their Morse codes back-to-back with no gap between them — the same small pause that normally separates one letter from the next simply isn’t there. That missing gap is the entire signal. It’s what tells a trained ear “this is a single procedural symbol,” not two letters.
Take AR as an example. Letter A is ·– and letter R is ·–·. Sent as two ordinary letters, you’d hear a distinct pause between them. Sent as the prosign AR, they run together into one unbroken shape: ·–·–·. Same dots and dashes, different timing, completely different meaning.
The Essential Morse Code Prosigns
These eight cover the vast majority of what you’ll hear in a typical CW contact, from opening a call to signing off.
Marks the formal end of a transmission or message, inviting a reply. The most common sign-off prosign in CW.
Sent when the entire QSO is finished and the frequency is free. Often nicknamed “silent key” in ham folklore, though its formal meaning is simply end of work.
Separates parts of a longer message, similar to a paragraph break. Often written as “=” in logs and paper copy.
Also written CT. Sent before a call to get the frequency’s attention that a transmission is about to begin.
An open invitation to transmit — identical to the plain letter K, sent alone after a call ends.
A more restrictive version of K — only the specific station being addressed should reply, not anyone else listening.
Asks the other operator to pause briefly — you need a moment before continuing.
Eight dots in a row. Sent the moment you notice a mistake — the correct text follows immediately after.
Prosigns in a Real QSO
Here’s a short, realistic exchange showing how prosigns actually thread through a contact between two stations, W1ABC and K5XYZ:
Prosigns vs. Q-Codes vs. Plain Abbreviations
It’s easy to lump these together since they all show up in the same CW conversations, but they’re three different things. Prosigns (AR, SK, BT…) are procedural, sent with no inter-letter gap, and control the flow of the contact itself. Q-codes (QRZ, QTH, QSL…) are three-letter groups sent as ordinary letters — with normal spacing — that stand in for whole questions or phrases, like “what is your location?” We cover the full Q-code list on the ham radio & CW page. Plain abbreviations (TNX, UR, GE, OM) are just shortened English words sent as normal letters to save time.
Frequently Asked Questions
What does SK mean in Morse code?
SK (···–·–) means the contact is complete and the frequency is now clear. It’s the standard CW sign-off, sent once both operators are done. The nickname “silent key” (used for a deceased ham) is a folk association, not its formal meaning.
What’s the difference between K and KN?
Both invite a reply, but K (–·–) is open to any station listening, while KN (–·––·) restricts the reply to the specific station you’re already in contact with — useful in a busy pileup or a scheduled contact where you don’t want other stations jumping in.
Do I need to know prosigns for my ham radio license exam?
Modern amateur radio license exams (in the US, the Technician, General, and Extra tests) no longer require Morse code proficiency at all, so prosigns aren’t tested directly. That said, if you plan to actually operate CW, learning AR, SK, K, KN, and BT early will make your first real contacts far easier to follow.
Are prosigns the same as Q-codes?
No. Prosigns (like AR and SK) are sent as a single merged symbol with no inter-letter spacing and control the mechanics of the conversation. Q-codes (like QRZ and QTH) are sent as normal, separately-spaced letters and stand in for entire questions or statements.