[amsat-bb] Doppler tuning on older radios

Hello group,

My Kenwood TM-455E (70cm all-mode transceiver) has no RS-232 interface, but it can be controlled in steps of 10 Hz using the microphone's up/down buttons.

What software/interface do I need to add automatic doppler tuning?

73, OZ1BXM Lars, Holstebro, Denmark, AMSAT #36222