All Icom HF and HF/VHF transceivers (except for the IC-701) provide an analogue band-selection voltage in the range 0 ~ +8V. This voltage serves to bandswitch external accessories such as the IC-2KL and IC-4KL amplifiers, the IC-AT150, IC-AT100 and IC-AT500 autotuners and the EX-627 antenna selector.The 18 and 21 MHz bands are grouped together, as are the 24 and 28 MHz bands. Zero voltage corresponds to 10 MHz. The 50 MHz band is not officially supported.Note: The band voltage follows the transmit band selection. When operating split, the band selected on the transmit VFO determines the band voltage (and thus the band selection in the external equipment), even if the transmit and receive VFO's are on different band. This is true whether the transmit VFO is active (assigned to the tuning knob) or not.
