I built this really simple to build circuit and it works just great!
Look around for a file called HFFAX.Zip or get a copy from a friend!

            SIMPLE FSK CIRCUIT FOR USE WITH PC FAX PROGRAM VER 4.0

                        AND MOST WEATHER FAX PROGRAMS

                            SCHEMATIC DIAGRAM

            TO RS232 PORT ON IBM PC AT,XT OR PS/2
           ^             ^                 ^
        PIN 4         PIN 6             PIN 20
           |             |                 |
           |             |                 |
           |-----------  |  -----|+  -|----|
           |             |        10 MF    |
           |             |                 |
           |----------|  |                 |
                      |  |                 |
                  NC  |  | NC              |    AUDIO         AUDIO
                   o  o  o  o              |    SHIELD        INPUT
                   |  |  |  |              |         ^            ^
                 ______________            |         |            |
                |              |           |         |            |
   NOTCH -------->) MCI741CP   |           |         |            |
                |______________|           |         |            |
                   |  |  |  |              |         |            |
                   o  o  o  o--------------|         |            |
                  NC  |  |___________________________|           ---
                      |  |                             .01 MF --->
                      |  |--------> PIN 7           CAPACITOR    ___
                      |  |                                        |
                      |  |___________________________ ---- _______|
                      |                               -^--        |
                      |                                |          |
                      |                           R1 1100 OHMS    |
                      |___________________________________________|


 LIST OF PARTS MANUFACTURER

      OF COURSE!!!  RADIO SHACK WE SEE THIS ALOT IN THE 73 MAG!!!


   MCI741CP   (OP AMP CHIP, PLEASE SEE RADIO SHACKS CROSS REF MAN)

        10    MICROFARAD ELECTROLYTIC CAPACITOR
       .01    MICROFARAD WAFER DISK CAPACITOR (NON ELECTROLYTIC)
       1100 OHM RESISTOR  1/2 WATT RATING

        PLEASE USE VOLTAGE RATINGS OF AT LEAST 30 VOLTS OR MORE
        WITH CAPACITORS SO THAT YOU HAVE GOOD QUALITY DEPENDABLE
        CIRCUIT ..


        YOU CAN MOUNT THE CICUIT ON A BREADBOARD OR CIRCUIT BOARD
        MAKE SURE YOU GROUND SHIELD THE CIRCUIT SO THAT YOU DONT
        HAVE ANY RFI PROBLEMS GOING TO HF RECEIVER VIA AUDIO
        WIRE CIRCUIT...~
 # SLMR 2.1a # It's only a hobby ... only a hobby ... only a RAMail 3.1
--  
Reid Kelly via cmhGate - Net 226 fido<=>uucp gateway Col, OH
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