The first and most important rule before using a repeater is to LISTEN. Nothing is more annoying than someone that "keys up" or doubles in the middle of another conversation without first checking to make sure the repeater is free.
If the repeater is in use, wait for a pause in the conversation, when the 'hand-over' takes place and simply announce your callsign and wait for one of the other stations to acknowledge your call.
If the repeater is not in use there is no need to call 'CQ' to initiate a conversation (though you can if you wish) on a repeater. Just simply key your mic and say your call sign & 'listening for any calls'. If someone happens to be listening and they want to talk to you they will respond. Some people say that they are 'checking access' and expect a reply from someone listening. When I did my Foundation Licence one of the tutors told us that 'checking access' should only be used to see if you are within range of the repeater and was not an invitation for a chat.
If you wish to talk to a specific operator then use their call-sign (twice is a good idea to make sure the repeater is 'up' and catch their attention) followed by your call-sign and something like 'are you there?'.
If you are already using the repeater and a station calls in it is polite to acknoweledge and go straight back to them, especially if they are mobile, as there could be a situation that requires assistance and the operator cannot get a mobile phone signal, or has no phone.
After contacting the 'break station' and if they do not require assistance, then they can be included in the normal conversation in turn with the other operators.
When you are using the repeater leave a couple of seconds between exchanges to allow other stations to join in or make a quick call. Most repeaters have a "Courtesy Tone" (a short beep or series of beeps) that will help in determining how long to pause. The courtesy tone serves two purposes. Repeaters have a time out function that will shut down the transmitter if the repeater is held on for a preset length of time (normally three or four minutes). This ensures that if someone's transmitter is stuck on for any reason, it won't hold the repeater's transmitter on indefinitely. (Don't laugh, many microphones get lodged in the fold of car seats and keep a repeater busy until it times out). If you wait until you hear this beep (normally a couple of seconds), before you respond, you can be sure that you are pausing a suitable length of time. After you hear the beep, the repeater's transmitter will stay on for a few more seconds before turning off. This is referred to as the "tail". The length of the tail will vary from repeater to repeater but the average is about 2 or 3 seconds. You don't have to wait for the tail to drop before keying up again, but make sure that you hear the courtesy tone before going ahead because if you don't wait for the beep, the time-out timer may not reset. If you time-out the repeater, your conversation after the time-out will not be heard, although CTCSS accessed repeaters usualy reset and only a small portion is lost. The repeater time-out function does not care if you are still talking or not; and the station on the other end may rib you about hogging the machine and you will have wasted all those words!
What is Doubling? It is when two stations try to talk at the same time on the same repeater or frequency), the signals mix in the receiver and results in a buzzing sound, squeal, distorted sound or severely jumbled and broken words.
Use plain language on a repeater. If you want to know someone's location, say "Where are you? or what's your location?" If you want to know whether someone you're talking with is using a mobile or a hand-held radio, just ask: "What kind of radio are you using?"
When you are involved in a roundtable discussion with several other stations it is always best to pass off the repeater to a specific person (station) rather than leave it up in the air. e.g.: "(call-sign) to take it, this is (your call-sign)", then de key, or: "Do you have any comments Fred?, this is (your call-sign)"; de key or even: "OK...that's all I have.....back to you (name of contact)" de key.
Failing to do this or other techniques is an invitation to total confusion, doubling etc.
Lots of newcomers (and old hands alike), when asked for a report give, for example, 5 by 9.
Well what's so bad about that?
On a repeater you can only give a readability report, the signal is what YOU receive from the REPEATER! If the repeater is always '30 over 9' EVERYBODY will give you that signal, regardless of the quality!
So how to give a report? Well listen to the background sounds of the AUDIO coming from your speaker in between words and sentences, if his audio is clear and no crackles etc then the signal is said to be 'fully quieting'. The term "Quieting" refers to the carrier level of the transmitter being strong enough to "quiet" the background hiss on the frequency. If some background noise such as the hiss that is commonly heard in an FM receiver is heard on the transmitters signal, then it would not be considered "fully quieting". There are times when either station using a repeater may be getting into the repeaters receiver with very little signal and the repeated signal will have lots of noise on it. Although the repeater signal may be full quieting when the weak station stops transmitting, the weak station can not be considered to be full quieting into the repeater so you would give the other station a report on his audio signal and not the repeater.
Don't get confused with this:
If his audio is perfectly understandable and there is NO "noise" in the background other than the slight FM hiss, then an accurate report for him would be, "You're full quieting into the repeater (or box)". Anything less than that is usually given in various ways using an exact as possible description of his signal, however "Audio" reports are a matter of interpretation by individual ears. I must admit that visually impaired operators are better at this than most.
If the station is in and out of range of the repeater you and he were using and is coming in your direction:- try listening to him on the input frequency! He may be loud and clear direct on simplex and only a few miles away and getting stronger all the time but he is getting farther from the repeater. Time to QSY to a simplex frequency!
Another situation that can happen during a new contact is that you and he did not exchange locations at the first of the contact. Both you and he are using a repeater 30 miles away. Then after several minutes you discover in your conversation with the other station that he is in the same town as you and only a couple of miles away, again it's time for simplex!