MFJ MFJ-1224 User manual

MFJ RTTY/CW
COMPUTER INTERFACE
MODEL MFJ-1224
OWNER'S MANUAL

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MFJ-1224 RTTY/CW COMPUTER INTERFACE
Thank you for purchasing the MFJ-1224 Interface. The MFJ-1224 will allow you to transmit
an receive RTTY an CW when use with your transceiver. During reception, the MFJ-1224 con-
verts the CW or AFSK tones from your receiver into computer compatible TTL level signals. The
computer then translates these signals into the represente alpha-numeric characters an isplays
them on the screen. In the Transmit Mo e, the computer generates the TTL signals which are con-
verte by the Interface into AFSK tones for RTTY or into CW keying for CW transmission.
NOTE: The interpretation of the TTL signals requires a specialize HAM program which is
not provi e with the interface. This allows you to select a program which is compatible with your
computer an which has the features you want.
When unpacking, make sure that all of these items are inclu e : (1) INTERFACE, (1) FOUR
PIN MIC PLUG, (1) RCA CABLE, (1) FIVE PIN PLUG, (1) MIC CABLE WITH FIVE PIN PLUG AT-
TACHED an (1) OWNERS MANUAL. THE 12-VDC AC-ADAPTER IS OPTIONAL.
FRONT PANEL
The front panel controls an in icators consist of five push button switches an four LEDs. From
left to right, they are as follows:
ON/OFF This switch controls the power to the interface.
POWER LED This in icator is lit when the power in on.
PHASE LOCK LED This in icator is use with the DATA in icator to ai in tuning the receiver. It
in icates when the interface is locke onto an RTTY signal. It flashes with
the Morse Co e tone for CW reception.
DATA LED This in icator is use with the PHASE LOCK in icator to ai in tuning the re-
ceiver. It flashes on an off with RTTY shift an also flashes with the Morse
Co e tone for CW reception.
CW Transmit LED This in icator is activate by the CW keying circuit. It flashes uring CW
transmission.
RTTY/CW This switch selects either the RTTY or CW mo e of operation.
Shift The next two switches control the shift for RTTY:
In this position the interface is set for a 850 Hz au io shift
In this position the interface is set for a 170 Hz au io shift
In this position the interface is set for a 425 Hz shift an 170 Hz
sen ing shift
In this position the interface is set for a 425 Hz shift an 850 Hz
shift
NORMAL/REVERSE This switch inverts the emo ulate RTTY signal being sent to the computer.

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BACK PANEL
The MFJ-1224 provi es inputs an outputs to allow interfacing to nearly any possible com-
bination of computer an transceiver. The back panel iagram below shows all the interface con-
nections an the paragraphs below escribe their uses. Only a few of the available connections will
be use for any given application; however, the available of a variety of signals greatly enhances
the versatility of the interface.
LOOP OUT The loop-out jack provi es the groun return to rive loop type teletypes.
The user must connect the negative supply voltage to the sleeve. The center
pin is a continuation of the negative supply. The loop out merely acts as a
spst switch switching the loop current on an off.
DIRECT KEYING This output keys rigs requiring irect keying(most rigs with soli state finals)
GRID BLOCK KEYING This output keys rigs requiring gri block keying (most rigs with tube finals)
KEY IN This input jack allows you to externally key the transmitter with your own
electronic keyer or keyboar .
DEMOD OUT The emo ulate output provi es a TTL level signal which correspon s to
the incoming RTTY or CW signal. This output is high on RTTY mark an low
on RTTY space. It is also low for CW tone.
The next connector is a five pin jack, labele K-connector because it is specifically esigne
for use with KANTRONICS software. From left to right the pins are as follows:
DEMOD This pin pro uces the same output as the DEMOD out jack.
GROUND This pin provi es the groun connections between the interface an the
computer.
CW KEY This input pin allows the computer to key the transmitter through the inter-
face. A low on this pin causes the interface to key the transmitter.
RTTY This input controls the AFSK for RTTY transmission. It works in conjunction
with CW ID signals an to operate the push-to-talk switch. This will be cov-
ere in etail later.
CW ID This line controls the au io tone for CW i entification. It works in conjunc-
tion with the RTTY line to pro uce RTTY an CW ID signals an operate the
push-to-talk switch. This will be covere in etail later.

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Next is a eight pin general purpose connector which allows you to a apt the interface to al-
most any computer an software. An internal DIP switch allows the inputs an outputs to be in-
verte if necessary to correspon to the requirements of your computer. From left to right, the
pins are as follows:
RTTY DEMOD This output is a TTL version of a receive RTTY signal.
GROUND This pin provi es the groun connection between the interface an the com-
puter.
CW ID This input pin controls the shift for CW ID transmission.
RTTY This input pin controls the mark an space shift for RTTY transmission.
PTT This input controls the push-to-talk switch of the transmitter.
CW KEY This input controls the transmitter keying circuit.
+5 VDC This input provi es a 5 volt supply for external circuitry such as an RS-232
converter.
Next is a five-pin jack which is use for the microphone connection. From left to right, the
pins are as follows:
PTT OUT This pin is connecte to the high si e of the push-to-talk line. It is shorte to
groun to key the microphone.
PTT GROUND This pin is connecte to the groun si e of the push-to-talk line.
AFSK SHIELD This pin is connecte to the groun for shiel si e of the AFSK line.
AFSK OUT This line carries the au io signal for AFSK RTTY to the microphone input.
FSK OUT This line provi es FSK signal for keying FSK rigs.
AUDIO IN The au io input jack shoul be connecte to the external speaker jack or
hea phone jack of your receiver with a shiel e au io cable. The interface
en of the cable requires an RCA type plug.
SPEAKER OUT The speaker output jack may be connecte to a speaker using shiel e
au io cable. The interface en of the cable requires an RCA type plug.
12 VDC The power jack requires 12 VDC from a 2.5 mm subminiature plug with the
tip positive an the sleeve groun .

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PRELIMINARY CONNECTIONS
Input an output signals must be TTL level (+5 VDC an groun ). Inputs are RTTY an CW
KEY (RTTY an CW on general purpose connector). There is also a separate CW ID input for i enti-
fying in MORSE while operating RTTY. Outputs are DEMOD (RTTY DEMOD an CW DEMOD on the
GENERAL PURPOSE CONNECTOR) an DIRECT an GRID BLOCK. Connections epen on the type
computer an transceiver use . Either the GENERAL CONNECTOR or the K-CONNECTOR will be
connecte to the computer.
CONNECTIONS
FOR CW For transmission an reception of CW, the following connections are necessary.
1.) A 12 VDC power supply to the POWER jack of the interface.
2.) A shiel e au io cable from the external speaker jack of the transceiver to the AUDIO in jack
of the interface.
3.) If esire , a speaker may be connecte to the SPEAKER out jack of interface.
4.) If the interface is to be use to key the transmitter by han , the key shoul be connecte to
the KEY in jack.
5.) The control cable from the computer to the interface.
6.) A cable from one of the KEY out jacks of the interface to the key in jack of the transceiver. If
you are not sure whether your transceiver requires GRID BLOCK or DIRECT KEYING, try one
an then the other to see which one works. No amage will be one if the wrong one is se-
lecte .
FOR RTTY/ASCII For transmission an reception of RTTY or ASCII signals the following con-
nections are nee e :
1.) A 12 VDC power supply to the POWER jack of the interface.
2.) A shiel e au io cable from the external speaker jack of the transceiver to the AUDIO in jack
of the interface.
3.) If esire , a speaker may be connecte to the SPEAKER out jack of the interface.
4.) The microphone/PTT cable to the transmitter. This cable is supplie with the proper push on
the connector on one en an with the other en unwire . This allows the cable to be con-
necte properly for various types of transmitters. For transmitters that have three wire
microphone connectors, only three of the microphone cable are nee e . AFSK shiel shoul be
connecte to groun , PTT shoul be connecte to PTT OUT an AFSK shoul be connecte to
the AUDIO INPUT. The FSK OUT is not connecte when use for AFSK operation.
Consult the owner's manual for your transceiver to etermine the proper connection of the
MICROPHONE JACK. The white wire is the au io line, the re wire is the PTT line, the black
wire is the PTT groun line, the bare (shiel ) wire is the au io groun an the green
wire is the FSK line.
5.) The control cable from the computer to the interface.
6.) If the interface is to rive a TTY current loop, the TTY shoul be connecte to the LOOP out
jack. The sleeve is the negative si e of your supply. The LOOP OUT pin is usually connecte to
the negative si e of your selector magnets.