
                              PC <-> FT-x12 CAT interface

                              1990 Marco Savegnago IW3FQG




                        Schematics for 1 radio on 1 serial port

                                        /-----\
                                 o------I  R  I---------> 2 +5v
                                 I      \-----/
                                 I
                                 I      + I/ I -
                                 o--------I  I ---------> 1 UP
                                 I        I\ I
                                 I
                             C   I      + I/ I -
                        I  / ----o--------I  I ---------> 3 DOWN
             /-----\  B I /   T           I\ I
 TD  2   <---I  R  I----I\
             \-----/    I  \   E
                            \
 GND 7   <-------------------I--------------------------> 7 GND



                Schematics for 2 radio on 1 serial port (shared)


                                                        /-----\
                                                    |---I  R  I----> 2 +5v
                                                    |   \-----/
                                                    |
                                 T    C             | + I/ I -
                 /-----\           I /------o------ o---I  I ------> 1 UP
RTS 4 <----------I  R  I-----------I\       | -     |   I\ I
                 \-----/         B I \ E   ---      |
                                     |     \ / D    | + I/ I -
                                     |     ---      |---I  I ------> 3 DOWN
                            T    C   |      | +         I\ I
             /-----\          I /--- |------o                    (RADIO 1)
TD 2  <------I  R  I----------I\     |      | +        /-----\
             \-----/        B I \ E  |     ---     |---I  R  I-----> 2 +5v
                                 |   |     / \     |   \-----/
                                 |   |     ---     |
                        T   C    |   |      | -    | + I/ I -
         /-----\          I /----|---|------o------o---I  I -------> 1 UP
DTR 20 <-I  R  I----------I\     |   |             |   I\ I
         \-----/        B I \ E  |   |             |
                             |   |   |             | + I/ I -
                             |   |   |             |---I  I -------> 3 DOWN
                             |   |   |                 I\ I
                             |   |   |                          (RADIO 2)
                             |   |   |
GND 7 <----------------------o---o---o-----------------------------> 7 GND

                                                                (on both RADIO)


        T = Common NPN Transistors (ex: BC238)
        R = 1 or 2 K (not critical)
        D = 1N4148.


If you aren't able to make this simple 'interface', you can buy the YAESU's!

This work can be freely distribute but not for commercial purposes!!!!!

Enjoy!

Marco IW3FQG.

