This Drawing is for adding multichannel control to a Storno Rig.  I have eprom codes for 2m and 4m that I have written. I will convert them and stick them up on the site next. This is the latest method I have used to for the eprom, Its very simple as well!

Two BCD output thumbswitches are use to drive the address codes on the eprom with 5v. Resistors are fitted to pull these lines to ground when not selected.  Repeater shift is obtained by having two sets of code, one for TX and one for RX. Shifting is obtained by feeding the TX switching signal into A8 address code (pin 25), make sure u fit the cap on this input to stop RF causing havoc!  The data output pins of the eprom drive the data inputs of the synth.

A 5 v rail was obtained via diodes from the 8v rail in the rig. Make sure the cap is mounted next to the Eprom. The 10K resistor makes sure the diodes are dropping the right amount of voltage!  I built this up on a small lump of vero and it fits in the small space beside the synth PCB that is left by the removal of the tone call board. When the two switches for the tone board where removed, it left me enough room for my thumbswitches, it depends on the size of the ones use are using.