ICCIIV.8 Appendix 2 -- Jumper Selections There are jumpers in the ICOM rigs to set the device address, baud rate, and to enable the group call feature. You must look on the schematic to find them. The jumper to enable the gr transceive enabled. I have specific information the 735 codes and the schematic. For the 735 - The jumpers use lines labeled DB0 through DB5 a nector J22 on the PL board. Lines DB0 through DB2 set the device address. Line DB3 is the transceive enable. The DB4 DB5 Baud 0 1 1 300 The 735 is set at the factory to add frequency or modulation mode manually. You will receive a group call packet that contains as its 4th byte the address of the rig.