HLN4902B MDC600 Encoder Board
http://cm.ebay.com/cm/ck/1065-22702-... em=3867641589

YLN4470A Single Tone Encoder Board
http://cm.ebay.com/cm/ck/1065-22702-... em=3867644731

Option Board Interconnect Cable
http://cm.ebay.com/cm/ck/1065-22702-... em=3867646784