Cut numbers
| Cut numbers | |
|---|---|
| What they are | Short letters sent in place of long Morse digits |
| Used in | CW contests, and some fast everyday CW |
| Best-known example | 5NN for the signal report 599 |
| Most common cuts | T for 0, N for 9, A for 1, E for 5 |
| Rules of use | |
| Where used | Number fields only: reports, serial numbers, zones, power |
| Never used in | Call signs |
| In the log | Always the real digits |
Cut numbers are shortened forms of the digits used in Morse code, mainly in CW contests. Every Morse digit is five elements long, and those with several dahs take a long time to send. Contesters replace them with short letters that keep the start of the digit's pattern: T (one dah) for 0, N (dah dit) for 9, A (dit dah) for 1 and so on. The best-known example is the contest signal report 599, which nearly everyone sends as 5NN.
Why they are used
Morse code gives letters short patterns and digits long ones. Counting a dit as one unit of time, a dah as three, and one unit of silence between the elements of a character, the digit 0 (five dahs) takes 19 units to send, while T takes 3. The digit 9 takes 17 units; N takes 5. Over a single contact the saving is small, but a contest exchange may contain several numbers, and a busy station may make well over a thousand contacts in a weekend. Shaving a second or two from every exchange adds up to more contacts and a higher score.
Cut numbers also suit the way contesters listen. In a numeric field, such as a serial number or a zone, the listener already expects digits, so a short letter in that position is easy to recognize and translate.
The cuts
Each cut letter is formed by shortening the digit's long run of dahs to a single dah, or, for 5, its run of dits to a single dit.
| Digit | Full Morse | Cut | Cut Morse |
|---|---|---|---|
| 1 | ·−−−− | A | ·− |
| 2 | ··−−− | U | ··− |
| 3 | ···−− | V | ···− |
| 4 | ····− | (usually sent in full) | |
| 5 | ····· | E | · |
| 6 | −···· | (usually sent in full) | |
| 7 | −−··· | B | −··· |
| 8 | −−−·· | D | −·· |
| 9 | −−−−· | N | −· |
| 0 | −−−−− | T (sometimes O) | − (or −−−) |
In practice the cuts for 0, 9 and 1 are by far the most common, followed by 5. The others are understood by experienced contesters but used less often, and some operators prefer to send them in full. A few operators send zero as a single extra-long dah rather than T.
Examples
- Signal report: 599 becomes 5NN. The 5 is usually left as a digit, because the report is so familiar that 5NN cannot be mistaken for anything else.
- Serial numbers: contact number 001 may be sent as TTA or TT1, and 100 as ATT. Many contests require a serial number, so these cuts are heard constantly.
- Zones: in the CQ World Wide DX Contest, a station in CQ zone 9 might send 5NN N, and one in zone 10 5NN AT.
- Power: in contests where the exchange is a power level, 100 watts may be sent as ATT.
Rules of thumb
Cut numbers are used only where a number is expected. They are never used in call signs, where letters and digits both appear and a T could not be told from a zero. They are also avoided in any field where letters are legitimate, such as an ARRL section or a state abbreviation.
The log must always record the real digits. A serial number received as TTA is entered as 001; a zone sent as N is entered as 9. Contest logs are cross-checked against each other after the event, and a miscopied number costs points.
Modern contest logging software handles the sending side automatically. Programs such as N1MM Logger+ can be set to send cut numbers for the report and the serial number from their function-key messages, with options for which digits to cut. On the receiving side, the operator, or any CW decoding software in use, must translate the letters back into digits.
Cut numbers are a CW custom only. On voice, numbers are simply spoken, as in "five nine" for 59.