You can download the schematic for the I/O Multiplexer and the BOM from this page.
Schematic

Bill of Material
Download the BOM Excel file below and order the material from the vendor of your choice.
Ham Radio controllers and unique station control accessories
You can download the schematic for the I/O Multiplexer and the BOM from this page.
Download the BOM Excel file below and order the material from the vendor of your choice.