MFJ MFJ-451, MFJ-451X User Manual

MFJ-451 Morse Keyboard Instruction Manual

The MFJ-451 Morse Keyboard sends Morse code from a keyboard. The MFJ-451
has two 100 character message memories and a 200 character type ahead buffer.
This unit can repeat messages continuously, insert timed pauses within messages,
and insert an auto-incrementing serial number. The speed, tone, and weight of the
code are keyboard adjustable. The MFJ-451 has a internal sidetone speaker with a
volume control on the front panel of the unit. The MFJ-451 has a paddle jack and
a connection for an external speaker.

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MFJ-451 Morse Keyboard Instruction Manual

MFJ-451 Morse Keyboard

FEATURES

Memories:

Two independent 100 character message memories.

Type Ahead Buffer:

The MFJ-451 has a 200 character type ahead buffer with audible buffer full warning.

Built-In Iambic Keyer

Using the paddle jack makes the MFJ-451 a keyboard controlled iambic keyer.

Embedded commands:

Auto-incrementing serial numbers, Timed pauses up to 99 minutes 99 seconds, Message loop.

Adjustable Parameters:

Code speed is variable from 5 to 100 WPM, weight varies from 5 to 95 %.

Sidetone Speaker:

Internal sidetone speaker with adjustable volume and frequency.

Output Tune Mode:

Constant key to tune tuners or antennas

Key Output Disable:

Enable and disable key output to practice operation

Handkey Mode:

Use the space bar or iambic paddle as a straight key.

INSTALLATION

The MFJ-451 is supplied with an IBM-AT compatible keyboard. The unit is guaranteed to support the
supplied keyboard but may be used with other standard 101 key AT style keyboards. Using an XT style

keyboard or turning a switchable keyboard to "X" mode may damage both the keyboard and the MFJ-

451. After checking the A-X switch on the back of the keyboard, plug the keyboard into the 5 pin DIN

connector marked KYBRD IN on the MFJ-451.

The MFJ-451 Morse Keyboard requires a 12 VDC 250 milliamp power supply. The power jack accepts a

2.1mm coaxial plug with the center conductor positive and shield ground. An optional DC supply, the
MFJ-1312B, is available from MFJ Enterprises. Connect your MFJ-1312B Power Adapter or compatible
DC supply into the jack marked POWER on the MFJ-451 back panel.

This unit supports both positive and negative keyed radios. Connect a standard shielded RCA cable
between your radio key input and to the MFJ-451's key output. The MFJ-451 is set up for a Direct or
positive keyed radio(most solid state radios). The unit can be set up for Grid Block or negative (most
radios with tube finals) by changing the internal jumper to the left most pair of pins on JMP1. JMP1 is
located, with the POWER switch toward you, to the right rear of the PC board.

A paddle connects to the 3.5mm stereo phone jack with a shielded cable through the back of the unit.
Connect the dot wire of the paddle to the ring on the plug and the dash wire to the center conductor. The
shield on the plug should be attached to paddle ground.

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MFJ-451 Morse Keyboard Instruction Manual

An external speaker can be connected to the external speaker output on the rear or the unit by using a

3.5mm plug.

KEYBOARD OPERATION

The Morse Keyboard is simple to operate. After turning the unit on, it will send the characters "ON" in
Morse code over the sidetone speaker and turn on the POWER LED. This tells you the MFJ-451 is ready
for operation. Now the memories can be set along with the speed, tone and weight of the Morse code. If
the volume is too low or too loud, adjust the volume control on the front of the unit.

After a key is pressed, a character will be sent to the key output and the speaker. If your typing speed is
faster than the code speed, characters will fill the type ahead buffer. Pressing the backspace key will
remove a character from the type ahead buffer before it is played. As the buffer is filled to 180 characters
the sidetone frequency lowers. When the buffer is full, an error tone will sound for every key that is
pressed. Any characters typed over 200 will be lost. As the code is played the buffer will empty.

While your type ahead buffer is emptying you may clear it by pressing Esc. The buffer will clear, all text in
it will be lost, and the keyer will stop playing code. Now you may enter new text or play a message.
If you press Pause while your type ahead buffer is playing your message will stop playing. You can now
insert text with the paddle. Press Esc and your type ahead buffer will continue playing where it stopped.

ADJUSTING CODE PARAMETERS

NOTE: While changing parameters or loading memories, the MFJ-451 disables the output key so that

erroneous code is not sent over the air.

Sidetone Frequency (F2)

To adjust sidetone frequency, press F2. The unit will sound the present tone setting. Use the up and down
arrow keys to increase or decrease the sidetone setting. Note that the tone will not affect your transmitted
signal, only the sidetone speaker frequency changes. When you have found a tone setting that you like,
press either Esc or Enter to exit the tone change mode.

Code WPM Speed (F3)

Code speed is set using the F3 key. After you press F3, the MFJ-451 sends a series of dot-dashes over the
sidetone speaker to indicate the current speed. There is only one method to change code speed. The up
and down arrow keys can be used to vary the speed gradually.

Weight (F4)

Weight is set with F4. After pressing F4, a series of dot-dashes is played from the sidetone speaker.
Pressing the up arrow key lengthens the on time of a dot or dash and shortens the off time. The down
arrow key shortens the dot or dash length. To exit press either Esc or Enter. This feature lets you
personalize your code and can help to avoid clipping if your radio or amplifier has a send delay. It can also
increase your power out by increasing on time.

Parameter Save

All code parameters and message memories are saved in nonvolatile memory. Memory life is rated greater
than 20 years.

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