For one repeater system that I was involved with that had two repeaters at the same location that we wanted to link, we started out with an
NHRC-7 controller. Nice enough controller, but it can only be programmed by DTMF commands on one of the three audio inputs. I replaced it with an Arcom
RC-210. A few more frills, a lot more capability in terms of macros, and much easier to program using their RCP software.