MFJ MFJ-52 User Manual

MFJ-52 Installation Manual

MFJ-52 Deviation Meter

The MFJ-52 Deviation Meter is a peak audio level meter board for The Net X-1
(J or later firmware). When using the MFJ-52 you will be able to tell quickly the
frequency deviation of all incoming signals. The value of deviation of all signals
which your MFJ TNC has heard are stored in the station "heard list".

Use the
information will be displayed after each station in the heard list: the number of
packets received from a station, how long ago the last packet was heard, the port
on which it was heard and the deviation of the last valid packet in kiloHertz. If
the deviation reading is overrange a ">" character will be displayed with the
deviation. Any station that has a deviation of 0 will have no deviation value
displayed.

With the MFJ-52 you must also have The Net X-1 (J or later firmware) EPROM.

MFJ does not offer this EPROM so it must be obtained from some other
source. You can get a copy of the X-1 software with the instructions for burning

an EPROM from your local Ham BBS or from Buck Rogers, K4ABT. See the
instructions on page 14 of this manual for details.

MHEARD

command to display the heard list. Several pieces of

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MFJ-52 Installation Manual

Installation

Do not attempt installation of the deviation board until you have the X-1 (J or
newer) EPROM. The MFJ-52 must be used with the X-1 The Net EPROM
otherwise the Deviation Meter circuitry is useless.

For this installation you will need the following:
A working MFJ-1270/1270B/1270C/1274/1274C
The MFJ-52, containing:
the MFJ-52 board
a plug with three wires attached (blue, black, white)
a 6" piece of violet 24 gauge wire
one 6-32 x 1/4" screw
a spacer for early TNC's that don't have one by the CPU
The X-1 (J or newer) EPROM with firmware

A low wattage

Rosin core solder
A #1 Phillips head screwdriver
A clean, organized, static free work area

Please follow the installation instructions carefully.

soldering iron (15 to 25 watts)

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MFJ-52 Installation Manual

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MFJ-52 Installation Manual

Installation Procedure

1. Disconnect all power supply voltages from the TNC in which the MFJ-52 is
to be installed.

2. Remove any cables from the terminal or computer.

3. Remove the bbRAM memory backup jumper
Figure 1.)

4. Remove the jumper from JMP 15 pins 2 & 3. Place this jumper on JMP 15
pin 3 only, as this jumper will needed if the MFJ-52 board is ever removed
from the TNC.

5. Use a screwdriver to gently pry up the Z80 CPU,
bend any pins too badly. Straighten any bent pins after removal.

6. Remove the system EPROM,
be used while using The Net. Keep the original EPROM in a safe place if
you wish to reinstall the MFJ code.

7. Install the Z80 CPU removed from the MFJ TNC in step #4 on the MFJ-52
in the socket labeled U1 in Figure 2.

NOTE:

8. Locate pin 1 of the X-1 EPROM. Pin one is the bottom leftmost pin when

Please note the orientation of the Z80 CPU in Figure 2 in order to

ensure that pin 1 is in the proper place.

the notch matches the notch in Figure 1. Bend pin 1 of the EPROM
outward so when you install the EPROM pin 1 is not inserted into the IC
socket.

. The original system EPROM will not

U23

JMP 5

on the TNC, (see

. Be careful not to

U22

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MFJ-52 Installation Manual

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