UHF radio transmission

My GME set has separte buttons for DUP and SCAN. To transmit in Duplex, turn off Scan and select required Duplex channel (1-8) then transmit. Duplex only works on these channels. Most sets will display "dup" if selected and if you are on channels 1-8. If another person transmits in Simplex on any channel and is within range you will here them regardless of what 'mode' tou are in !!
Hope this is correct and helps.

For duplex to work you have to be in range of a repeater.

For instance if there was a repeater nearby on Channel 1, when you select duplex on you radio you are actually transmitting on Channel 31 to the repeater, the repeater retransmits your signal on Channel 1.

Of course if you are using Channel 1 in its normal simplex mode, say to talk from car to car you will hear everything coming from the repeater, thats why you don't normally travel in convoy using channels 1-8 or for that matter 31-38.

To answer the last part of your question, say you were using Channel 2 on simplex from car to car and you heard another conversation coming through from a repeater you may be able to talk to them if they are withing range as they are listening on Channel 2 but transmitting on Channel 32 through a repeater. There is a good chance that they could be out of your normal transmit range although they sound to be loud and clear.

Clear as mud isn't it

Regards, Jim

Tony I think the best suggestion I can give is to get the handbook out and go through all of the scenarios with the radio and handbook in front of you. Selecting duplex won't stop scanning. You select duplex for particular channels (1-8). Scanning then goes on as normal and if there is someone on a duplex channel you will hear them. You can transmit on the channel your radio stops on or you can switch scan off and choose any channel you wish. If your radio has group scan you can select a "Priority Channel". The radio then checks the channel chosen for priority and any transmission on that channel is heard. Also if you press the talk button your radio will go to that channel immediately. In normal scan you transmit where the radio stops or as previously said you can turn scan off and select a channel manually.

What brand/model or radio do you have?