Explained pretty well above.
On our system one simply selects the freq one requires for the different sectors and then press a button marked "COUPLE" that then feeds them all in to one. If anyone tx on any other freq the call is transmitted out at the same time on all the other relays and transmittors so to allow everyone to hear. Very nice peter
Maybe some techie can explain how this little marvel actually works to band box everything altogh I'm sure its the same/similar principle of a normal VHF relay