MFJ MFJ-1270X Instruction Manual

MFJ ENTERPRISES, INC.

300 Industrial Park Road

Starkville, MS 39759 USA

Tel: [phone] Fax: [phone]

CAUTION: Read All Instructions Before Operating Equipment !

INSTRUCTION MANUAL

TNC-X Packet Controller

Model MFJ-1270X

V E RS ION 2A COP YR IGH T 2 013 MF J EN T ER P R I S E S , I NC.

MFJ-1270X Instruction Manual TNC-X Packet Contoller

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DISCLAIMER

Information in this manual is designed for user purposes only and is
not intended to supersede information contained in customer
regulations, technical manuals/documents, positional handbooks, or
other official publications. The copy of this manual provided to the
customer will not be updated to reflect current data.

Customers using this manual should report errors or omissions,
recommendations for improvements, or other comments to MFJ
Enterprises, 300 Industrial Park Road, Starkville, MS 39759. Phone:
[phone]; FAX: [phone]. Business hours: M-F 8-4:30 CST.

MFJ-1270X Instruction Manual TNC-X Packet Contoller

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Introduction................................................................................................ 4

Power Requirements .........................................................................5

Terminal Speed..................................................................................5

Setup If You Are Using USB..................................................................5

Setup If You Are Using the TNC’s Serial Port .......................................6

Back Connections..................................................................................6

Radio Setup...............................................................................................7

Radio Port Connections........................ Error! Bookmark not defined.

Cables ................................................................................................8

Radio Connection ..................................................................................8

Setup and Troubleshooting .......................................................................9

Receive Testing .....................................................................................9

Transmit Testing ................................................................................9

Can receive another node but can not get the node to respond. ......9

Can transmit but not receive the node. Can not hear a working node.

.........................................................................................................10

1270X seems to receive but the computer is not displaying the

received data or is not making the TNC to transmit. .......................10

Additional Troubleshooting ..............................................................11

Voltage Supply .................................................................................12

Testing for Defective IC Chips .........................................................12

TNC Programs.....................................................................................13

MFJ-1270X Instruction Manual TNC-X Packet Contoller

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MFJ-1270X TNC-X Packet Contoller

For VHF Packet and APRS

Introduction

Thank you for purchasing the MFJ-1270X TNC-X Packet Controller. The
MFJ-1270X is a new Terminal Node Controller design based on the
Chepponis/Karn KISS protocol. It is implemented using a Microchip PIC
16F628A microcontroller, a CML MX614 Bell 202 modem chip, an 8K
Ramtron FRAM, a MAX232A level converter chip, and an op-amp which
provides active audio filtering for the modem. From the beginning, this
TNC was designed to be small, inexpensive, have low power
consumption, and expandable.

The MFJ-1270X features an on- board USB port. The USB port was
added because the design took into consideration that computers these
days lack the old style RS-232 serial ports. There is also an 8-pin
expansion header that allows the addition of "daughter boards". Power
is provided to the daughter board through the expansion header. In
addition, signals that would otherwise go to or from a host PC can be
intercepted by the daughter board at the TTL level and processed. The
I/O on the expansion header speaks "KISS" so that any daughter board
only has to send and receive data packaged in KISS format to access
the core module. This makes the development of daughter boards fairly
simple and inexpensive. For example, daughter boards are now
available that can turn the MFJ-1270X into either of two types of
digipeaters via the MFJ-1270DG, or into a stand alone APRS Tracker
with the Coastal Chip Works X-Track board (http://tnc-x.com/).

In addition, the expansion header provides access to a second on-board
serial port. The X -Track daughter board, for example, uses this port to
receive data from a GPS receiver. The data is then processed and
formed into packets and an APRS beacon is sent. Even without daughter
boards the MFJ-1270X works as a fully functional stand alone KISS
mode TNC.

The idea behind the expansion options was to provide a platform that
would allow additional functionality to be added to the unit with the
investment of very little design time and very few parts.

MFJ-1270X Instruction Manual TNC-X Packet Contoller

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Power Requirements

IMPORTANT: DO NOT PLUG IN THE 8-15 VDC POWER SUPPLY
AND THE 9-VOLT BATTERY AT THE SAME TIME

The power requirements of the MFJ-1270X are very minimal due to
the low power consumption of the design. Using an 8-15 volt DC
power supply capable of 200-300 mA is well within the consumption
specifications. There is also a 9-volt battery snap provided for a 9-volt
battery. This makes the TNC more portable for campers and
backpackers.

IMPORTANT: DO NOT PLUG IN THE 8-15 VDC POWER SUPPLY
AND THE 9-VOLT BATTERY AT THE SAME TIME

Terminal Speed

The MFJ-1270X supports only 4 terminal speeds. Jumpers JP1 and JP2
determine the speed strictly for the link between the TNC and the
computer. The following settings are allowed:

JP1 JP2

Port Speed (Baud rate)

ON ON 1200 (Default Speed)

ON OFF 4800

OFF ON 9600

OFF OFF 19200

Note that the terminal speed setting does not affect the speed to transmit
data. The out-going or transmit speed is always 1200 baud. Note also
that if you set this baud rate faster than 1200 baud, it is possible for data
to be fed into the modem faster than it can transmit it over the air. This
may eventually result in the transmit buffer filling up.

Setup If You Are Using USB

If you have elected to use the USB port to provide data communications
to your PC, you should begin by acquiring and installing the drivers for
the PC and operating system that you are using. The USB IC used is an
FTDI chip. The driver you need is a Virtual Com Port (VCP) driver can
be found at :http://www.ftdichip.com/Drivers/VCP.htm if the operating
system you use does not automatically locate the drivers. It will make
the TNC appear as an additional com port on your computer so that you
can use any packet radio software that supports a KISS TNC connected
to a standard serial port.