The IC-FR5100/FR6100 series have an internal space for installing an optional RF unit, UR-FR5100 or UR-FR6100. Two RF modules can be installed in a chassis reducing installation space, and increasing channel capacity. They can be programmed and operated independently. Employing a high performance power amplifier, the IC-FR5100 series provides a reliable 100% duty cycle operation at 25W output. When need higher power, the optional UR-PA5000 series power amplifier provides 50W output power with 100% duty cycle. The IC-FR5100/FR6100 series detects multiple CTCSS and DTCS on a channel (up to 16 tones on a table) and downlinks (transmits) the received signal with a specified tone. This function is useful for sharing a channel with multiple groups.