Mode of Operation:
Set headphone switcher to Auto and listen and watch the SDR (software defined receiver) with PC. When you see a station on the SDR waterfall you can click the mouse on the screen to tune the SDR to that station. The IC-746 tuning is synchronised with the SDR by an addin .dll (now uses Omnirig) to the SDR software (Winrad). Transmit using the IC-746 and the headphones will switch automatically to the ICOM and back to the SDR when you have finished transmitting. The SDR will be muted automatically during transmit, SDR antenna input is shorted and ENRX loop is opened via a relay in the SDR enclosure. When the headphone switcher is not in use the SDR will still function correctly i.e when the ICOM-746 is off.
Each radio has it's own antenna.
The supply for the relays is derived from the ACC(2) port. The headphone switcher box is linked to the SDR Mute Circuit, that is within the SDR enclosure, via a coax, using push-pull latching connectors (Lemo 00 series).