Morse code for 0 (zero)


this question might be off-topic here in the SOTA reflector, but I ask myself, if it is common use to send one - (dah) instead of five ----- for the digit 0 (zero).
I never heard this on a SOTA activation before, even though -. (dah dit) for the digit 9 seems to be quite popular, at least when giving reports.
I’ve seen the morse code table at Morse code - Wikipedia contains this short code as an old alternative.
All my tomorrow’s summit references contain two 0, so maybe I should give it a try to save some time :wink:
Any opinions?

73 Stephan, DM1LE

In reply to DM1LE:

It’s normally sent as a long dah, say 5 or 6 dits long. Hard to do with a paddle and keyer!


In reply to DM1LE:
Hi Stephan,
Yes I use it mostly of time (not to say all the time… It’s shortly morse code for numbers… I saw that on time but can’t remember where (in army or … ) Can’t really remember but I use it fine ! :wink: So I think !

In reply to DM1LE:

Hi Stephan,

Yes, a long dah is often used for zero - maybe two or three times the length of a standard dah. I am sure everyone will understand when you send them in the SOTA reference.

On the subject of dahs, you missed the first one off my callsign when we worked on 7th June. It made a change to be logged as being in the USA. I am often logged as R4OIG. Maybe I need a long dah at the beginning of my call, Hi!

73, Gerald G4OIG

It is very rarely used as the zero in callsigns, where ----- is usually still used.

It is often used for leading zeros in SOTA references; eg SP-001 = “… .–. - - .----”.


In reply to DM1LE:
Dah is also T (Ten), similarly Dah Dit is N (Nine). Thats how this CW rookie sees it. Much easier to send if your key is precariously balanced somewhere, but sounds strange to start with. Dah, Dah, Dah-dit for 009 will get most chasers thinking!

What’s the opinion of the CW experts?

I’ll listen for you, but it is Father’s Day in the UK tomorrow, and I’m expecting a visit from our daughter sometime.

Best regards, Dave, G6DTN

In reply to DM1LE:

No need also to key leading zeros.
Es besteht keine Notwendigkeit, führende Nullen auch zu senden. Die meisten Chaser verstehen das auf Anhieb.

73 es gl, Heinz HB9BCB

In reply to MM0FMF:

There are abbreviated forms of eight of the ten numerical digits in Morse Code.

0 = dah
1 = dit dah
2 = dit dit dah
3 = dit dit dit dah
5 = dit
7 = dah dit dit dit
8 = dah dit dit
9 = dah dit

In practice, the only ones I have ever heard used on the amateur bands are
0, 1, 5 and 9. These can quite often be heard in CW contests. Abbreviated numbers should never be used in callsigns … it would be a recipe for total confusion!

… … de G3NYY

Another common abbreviation for zero is o, i.e. dah dah dah. I regularly use either dah or dah dah dah when giving summit references.

Since my SKCC number, 1113T, takes awhile to send with a straight key I used to use A for 1 to speed things when I sent a repeat of the number; i.e. I’d send something like “KE5AKL AZ MIKE 1113T AAA3T”. This often confused people so I stopped doing it.

Back when the number of SKCC members was lower there was never any confusion about the T at the end but with the advent of 5 digit SKCC numbers I’ve found that if I linger a little too long on the ending T folks sometimes think it’s a zero so now I’m careful to send it crisply.



In reply to G3NYY:

Abbreviated numbers should never be used in callsigns … it would be
a recipe for total confusion!

Indeed, not to mention against the license terms where it says callsigns should always be sent in full. (At least I think thats what it still says)

I’ve also heard the letter ‘O’ sent for Zero, not as short as sending ‘T’ but makes it a bit more obvious when written down.

Colin G8TMV

In reply to G8TMV:

says callsigns should always be sent in full.

That means sending all the characters in the call, how you send all the characters is (correctly) not defined.

So when you hear buffoons on a repeater say

“8TMV, what do you reckon Walt?”
“3NYY, I think this is a great repeater! Hang on I’ll take a K”
“break, break, break, 6GNL here, you’re very strong in Ealing Walt”
“3NYY, It’s the Heil mike I use.”

Then they are not sending the full callsigns by dropping the leading G or M or 2.



In reply to all:

Thank’s for all the helpful replies.
So, it’s not so uncommon as I had first assumed, but it should be used with caution, especially in callsigns it shall be avoided.

Gerald, sorry for the mistake, I’ve fixed it in my log.

Walt, and I thought in the past when I heard … … it is sloppy sending, but now it is perfectly acceptable :slight_smile:

73 Stephan, DM1LE

I always used to send all the dahs but then heard other SOTA activators sending just a single dah for zero. I’ve been using a single dah for zeros in the reference for a couple of years, it seems to work fine for me. It does seem tedious sending ten dahs in a row when two will do!

I do tend to leave a long gap between dahs, eg G/NP T T 4 for Whernside G/NP-004. I never cut the last numbers though, eg G/NP-010 as G/NP T 10.

The chaser is expecting a set pattern for the reference so it seems obvious to me what is meant by changing the leading zeros to just one dash.

I changed my call sign in order to ditch the zero to make it less tedious to send (Andy, I really don’t envy your call!).


In reply to MM0FMF:

“you’re very strong in Ealing Walt”

ROTFLMAO. Pure nostalgia!

Do you realise that was 40 years ago?


73 de Wlat

In reply to DM1LE:
Hi Stephan,

Don’t overlook the new operators who have learned CW solely to work SOTA stations especially DX and those of us who are trying to regain old skills briefly learned. We are struggling to get more than call signs and reports at the best of times. While “N for 9” is easy enough to cope with and well understood, when your signal is fading and not strong even on peaks you are pushing your luck if you send any other abbreviation for numbers. Of course now I know some of you might send abbreviations for numbers I might be able to make sense of what otherwise would be gibberish but please don’t assume that I will.

73 (I had thought B V was something quite rude)

In reply to DM1LE:
I am OLD School and Licensed in 1961 at the Age of 14 and been doing Cw for 54 years now and I send It like it should be All but RST Reports in 599 exchange.
Dow [W4DOW]
#1 SOTA Chaser W4V

The use of T for zero, N for nine, etc. is known as using “cut numbers”. Cut numbers are extremely common in amateur radio CW, especially in contests for the RST and serial number. E.g. ENN TTA is unambiguously 599 001. Most competent CW operators will have no difficulty with cut numbers used in this fashion.

The most important rule is that cut numbers are ONLY used when the context makes it unambiguously obvious that it is a number that is being sent. So cut numbers are never used in callsigns, for example. Using cut numbers in SOTA references is OK, because the format of a SOTA reference always has two letters followed by three numbers.

T for Zero and N for 9 are commonly used.
E for 5 and A for 1 rather less so.
The other cut numbers are almost never used because they offer little benefit.

John, G3WGV

In reply to G3WGV:
Hi John,
Thanks for the info. It’s 40 years since I had a CW contest contact and I only ever had the minimum to validate an entry. Now I know the protocol I will be better prepared. Cut numbers in a callsign or in fact anywhere other than RST would still throw me although I can see some using them in SOTA references.

The possibility of using very small transceivers and working DX peaks has rekindled my interest in CW.

Until this thread started I was oblivious of any other short cut other than N for nine which made some sense. T for zero is less obvious unless it is a long dash which my paddle won’t do so I won’t use it. I’m happy to send 5 dits so E for 5 is another I’ll leave alone.

Thanks to you and others on this thread I have learned a little more.


One more:
In contests T for a leading zero ok because most widely known (of course 5nn in RST). Only with seemingly experienced operators on the other side N in the serial number, even rarer A for one (exception nearly always A4 in WWDX when everyone from DL has to send 14, so exchange derived already from callsign…) and never “dit” for five other than the acknowledging and qso-terminating dit-dit which may substitute “TU” as the final, inviting the other callers to call.

In SOTA with a rather week signal and a community not active to fight for every thenth of a second never cut numbers. If there is difficulty to read a signal things must go as clear as possible which also means as standardized as possible, so no cut numbers other than 5nn.

(I once sent in a contest someone who used a lot of cut numbers my report as “ENN T7E” for 599 075 - guess how many repeats he needed…)

Chris DL8MBS

In reply to DL8MBS:

and never “dit” for five other than the acknowledging and qso-terminating

Amazing! It never occurred to me that the terminating “dit-dit” could be interpreted as “55”. How interesting!

I suppose I never thought of it before because the “55” greeting is only commonly used in German-speaking countries, and almost never in the UK.

I learn something new every day! Thanks, Chris.

Walt (G3NYY)