uhf protocol

UHF Channels are not used correctly in most places, but I spose you can try! ;-)
As far as I am aware it goes somthing like this:
Caravans: 18
trucks: 40 (or general highway use)
4x4 clubs: 10-18
emergency: 5 (duplex mode)
repeaters: 1-8 (repeat list availble on this site)
data/telemetry only for farming equipment? (do not use): 22-23
(about this data channel I have never heard any telemtry, however i spose in more remote areas stations might be running wells and bores with telemetry so make sure there isn't any weird modem like noises before using.

Just be polite, say "breaker" if you want to join in on some one else's conversation and wait to be aknoledged, but alot of it's just common sense. Just be polite and she'll be right!
I normally have two radios, one scanning all channels and one on my convey channel. That way I can here what everyone else is up to as well as not missing any important convo's from my group.

Duplex is what you use if you want to talk on a repeater. A Repeater is a radio setup somewhere high with a very good beam antenna/s to allow you to talk much further than you normally could from one radio to another.
When duplex is turned on (normally can only be activated on channels 1 through 8) when you hold your transmit button down and talk it will transmit on a totally different channel to the one displayed on your radio. ie

Transmit on channel 1 with duplex activated you will actually transmit on channel 31.
Why?? Because the repeater is listening on channel 31 and then re-transmits your signal on channel 1 so that people all over the place can here you.
2=32
3=33
4=34 etc.
Ergo you should not talk on chanels 1-8 in simplex (without duplex on) and you should not talk at all on channels 31-38.

A couple of bits to add:

1. To find out what is the local repeater when you don't have a local UHF map and need to call for help, switch to duplex mode on channel 1-8 and briefly transmit on each channel. When you get the right channel, you'll hear a morse code identifier from the repeater when you stop transmitting. Of course this only works when you are within range of a repeater.

2. Telemetry is being more and more widely used to monitor Outback bores, tanks, pumps, etc. I live in Oodnadatta, and one of the local cattle stations uses the channel 4 repeater to monitor all their water sources. They can even start the diesel pump remotely, then monitor water flow into the tank. This is partly why it's best not to use the repeater channels for convoy chit chat.

Cheers
jiarna