MFJ MFJ-1270C User Manual

o 15.838 Class B computing device: information to user.
This equipment generates and uses radio frequency energy and if not installed
and used properly, that is, in strict accordance with the manufacturer's
instructions, may cause interference to radio and television reception. It has
been type tested and found to comply with the limits for a Class B computing
device in accordance with the specifications in subpart J of Part 15 of FCC
Rules, which are designed to provide reasonable protection against such
interference in a residential installation. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does
cause interference to radio or television reception, which can be determined by
turning the equipment off and on, the user is encouraged to try to correct the
interference by one or more of the following measure:
Reorient the receiving antenna
Relocate the computer with respect to the receiver
Move the computer away from the receiver
Plug the computer into a different outlet so that computer and receiver are
on different branch circuits.
If necessary, the user should consult the dealer or an experienced radio/television
technician for additional suggestions. The user may find the following booklet
prepared by the Federal Communications Commission helpful:
"How to Identify and Resolve Radio-TV Interference Problems".
This booklet is available from the U.S. Government Printing Office,
Washington, DC 20402, Stock No. 004-000-00345-4.
Warning-When connecting this device to your computer,
shielded interface cables must be used.

MFJ MFJ-1270C Specifications

General

Power Supply	12 V DC
Protocols	AX.25
Power Output	Not applicable
Type	TNC
Frequency Range	Not applicable
Data Rate/Baud Rates	300, 1200 Baud
Connectors	DB-9
Mode	Packet

Summary

INTRODUCTION

COMPUTER INTERFACING

Computers with Specific Serial Interfaces

Specific wiring and setup details for popular computers.

RADIO INTERFACING

MFJ TNC Radio Port

Details the pinout and connections for the MFJ TNC's radio port.

RADIO INTERFACING METHODS

Presents two methods for connecting the MFJ TNC to a radio.

GETTING STARTED

Basic Parameters Setup

Guides on setting essential parameters like callsign for TNC operation.

Serial Port Configuration

Commands for configuring the MFJ TNC's serial port for optimal computer communication.

PACKET OPERATION

A Connecting and Disconnecting Exercise

Practical steps to establish and terminate a packet radio connection.

HF Packet Basic Operation

Specific considerations for operating packet communication on HF bands.

ADVANCED PACKET OPERATION

Packet Operating Modes

Describes Command, Converse, and Transparent modes for MFJ TNC operation.

Flow Control

TROUBLESHOOTING

General Tests

Specific Symptoms

Diagnosing common problems based on symptoms like TNC appearing dead or receiving gibberish.

PACKET RADIO PROTOCOL

Data Link Layer

Channel Flow Control

APPENDIX A: RADIO HOOKUP

RADIO HOOKUP

APPENDIX B: CALIBRATION

MODEM CALIBRATION

Procedures for calibrating the modem's modulator and demodulator frequencies.

Demodulator Center Frequency Alignment

Tuning Indicator Alignment

APPENDIX C: AUDIO OUTPUT

AUDIO OUTPUT CALIBRATION

Steps to adjust and calibrate the transmit audio output levels.

APPENDIX D: ALIGNMENT

HF RADIO ALIGNMENT

Methods to determine radio filter center frequency for modem alignment.