MFJ-1270C/1274C MANUAL HARDWARE
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Pin 10 Transmitter Key Input
This pin is physically tied to pin 6, above. It is used in conjunction with pin
9, above to allow the MFJ-TNC to use the on-board modem whenever the
transmitter is activated.
Pin 11 Transmitter Clock (16x) Input
This pin is tied to the NRZ-to-NRZI converter, which expects a clock signal at
16 times the desired radio port data rate, e.g., 4800 Hz for 300 baud. This pin is
normally jumpered to pin 12 when the on-board modem is used.
Pin 12 Transmitter Clock (16x) Output
This pin is tied to the radio baud rate switch network. It provides a clock at 16
times the desired radio port data rate. This pin is normally jumpered to pin 11
when the on-board modem is used.
Pin 13 Receive Clock Input
This pin is tied to the SIO receive clock input pin. It expects a clock at the
desired data rate (1200 Hz for 1200 baud), of the proper phase relationship to
the received data. This pin is normally jumpered to pin 14 when the on-board
modem is used.
Pin 14 Receive Clock Output
This pin is the received data clock signal derived from the NRZI-to-NRZ state
machine. This pin is normally jumpered to pin 13 when the on-board modem is
used.
Pin 15 MFJ-TNC Ground Reference
This pin ties to the MFJ-TNC digital ground system, at the SIO.
Pin 16 Turbo LED output
This pin is used to connect the Turbo LED on the mother board to the external
modem board. When this pin is high (+5Vdc), the Turbo LED will light.
