FT980

           COMPUTER INTERFACE CIRCUIT FOR CAT CONTROL (IBM GROUP)  

                          +9v to +12v (9v battery OK)
                                        +| | -  Add DPST switch at X's
 TO IBM/COMPATIBLE  ----------------O -X-||||--
 |                  |               |    | |  _|_         TO RADIO
                    |               <         ///    (Numbers shown are
 232 CONNECTOR      |               <10 k            for 6 pin din conn. 
 |                  |               <                for FT-980 only)
                    |               |
1<----o--------------------------------------------o---------->(1) GND
7<----|             |               |              |
                    |               |              |          |
 |                  |/|2    100 k   |              |
                   4/+|-----/\/\----|------------------------->(2) TTL
 |                 /  |             |              |             SIGS
        3.3 k   1 /   |             |              |          |  FROM
3<------/\/\-----/ U1A|             |              |             RADIO
                 \    |             |              |          |
 |                \   |             |      |\ |    |
                   \  |3            |      | \|    |          |
 |                  \-|-----/\/\----o------| /|----o
                     \|     100 k          |/ |    |          |
 |                                         1N914   |
              -----\/\/-------      (Radio Shack   |          |
 |            |     100 k    |       276-1122)     |
              |  |\          |                     |          |
2<------/\/\--o--|-\         |                     |
         18 k   6|  \        |              | /|   |          |
 |               |   \ 7     |              |/ |   |
                 |U1B \------o----/\/\------|\ |----------o--->(3) TTL
                 |    /            47       | \|   |      |      SIGS
2                 |   /11                   1N914   |      |      TO
                 |  /|                             |      |      RADIO
            -----|+/ |   U1  LM324 Quad Op Amp     |      |
            |   5|/  |   (Radio Shack 276-1711)    |    ------
            |        |                             |      /\1N914
            |        |  Build circuit on bread-    |     /  \ 
            >        |  board(Radio Shk 276-175)   |     ----    
            > 100 k  |                             |      |
            >        |            - | | +          |      |
            |        O --X---------||||---|        |      |
           _|_         -9v to -12v  | |  _|_      _|_    _|_
           ///         (9v battery OK)   ///      ///    ///

      For use with any interface activity. Schematic in Public Domain.
   (For an FT-980 radio CAT control program download CAT980 or contact:

            K5YEF/Art Harding/PO Box 861719/Plano, Tx. 75074/USA