TM431 for 9600 bps packet radio

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9600 bps modification for TM431A


Connect AC coupled TX audio to MO input at PLL circuit board (X58-3480-00)
through a 100 kohm resistor.

Connect RX audio to DET output pin 12 at IC1 (FM IF HIC)

The only problem is that you must mute the TX audio when you RX,
because this way you modulate the PLL.

You can find these pins when you open the bottom cover.
Locate the four points where the PLL circuit cover is soldered to.
They are marked with X in the drawing.


                     FRONT PANEL



                X                       X
                o
                o
                o
              o
              o
              o
          MO> o
                X                       X
                                       oooooooooooooooo
                                           ^DET

73 de OH3NWQ

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