MFJ-1270C/1274C MANUAL APPENDIX F: JUMPERS
Page 247
JUMPER FUNCTIONS AND LOCATIONS
The MFJ-TNC mother board has many jumper connectors. Each jumper
connector has a special function. The Jumper Function chart in this appendix
will help in identifying each jumper function. Figure G-1 will help in locating the
jumper connectors easily.
For normal operation a shorting jumper must be placed on the following
connectors: JMP 5; JMP 8; JMP 9 pins 2,3; JMP 13; JMP 18 pins 1,2; JMP 15
pins 2,3; JMP 26 pins 1,2. Also on the modem disconnect header J4 the
following pins need jumpers pins 1,2 11,12 13,14 17,18.
Table G-1
: Jumper Function
Jumper # Position Function
JMP1 Pin 1 & 2 !DCD (RS-232C) stays on
Pin 2 & 3 !DCD (RS-232C) stays off
OFF (default) !DCD reflects connect status
JMP2 Pin 1 & 2 (default) 4.92 MHz CPU clock
Pin 2 & 3 2.46 MHz CPU clock
JMP4 ON disable Tx watch-dog
OFF (default) enable Tx watch-dog
JMP5 ON (default) Lithium battery connected
OFF Lithium battery disconnected
JMP7 ON analog loopback mode
OFF (default) normal modem operation
JMP8 ON (default) demodulator enabled
OFF demodulator calibrate
JMP9 Pin 1 & 2 calibrate U16 tones
Pin 2 & 3 (default) normal modem operation
JMP10 ON digital loopback mode
OFF (default) normal modem operation
JMP11 LEFT transmit data NRZ NEED PIN #
RIGHT (default) transmit data NRZI
JMP13 ON (default) TTL, RTS enable
OFF TTL, RTS disable
JMP15 Pin 1 & 2 (default) 256K firmware EPROM
Pin 2&3 512K bit firmware EPROM
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