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MFJ -1224 Instruction Manual

Rtty/cw computer interface
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MFJ-1224 Instruction Manual
MFJ-1224 RTTY/CW COMPUTER INTERFACE
Thank you for purchasing the MFJ-1224 Interface. The MFJ-1224 will allow you to
transmit and receive RTTY and CW when used with your transceiver. During reception,
the MFJ-1224 converts the CW or AFSK tones from your receiver into computer
compatible TTL level signals.
represented alpha-numeric characters and displays them on the screen. In the Transmit
Mode, the computer generates the TTL signals which are converted by the Interface into
AFSK tones for RTTY or into CW keying for CW transmission.
NOTE: The interpretation of the TTL signals requires a specialized HAM program which
is not provided with the interface. This allows you to select a program which is
compatible with your computer and which has the features you want.
When unpacking, make sure that all of these items are included; (1) INTERFACE, (1)
EIGHT PIN MIC PLUG, (1) RCA CABLE, (1) FIVE PIN PLUG, (1)MIC CABLE WITH
FIVE PIN PLUG ATTACHED, and (1) OWNERS MANUAL.
ADAPTER IS OPTIONAL.
FRONT PANEL
The front panel controls and indicators consist of five push button switches and four
L.E.D.'s. From left to right, they are as follows;
ON/OFF This switch controls the power to the interface.
POWER L.E.D. This indicator is lit when the power in on.
PHASE LOCK L.E.D. This indicator is used with the DATA indicator to aid in tuning
the receiver. It indicates when the interface is locked onto an RTTY signal. It flashes
with the Morse Code tone for CW reception.
DATA L.E.D. This indicator is used with the PHASE LOCK indicator to aid in tuning
the receiver. It flashes on and off with RTTY shift and also flashes with the Morse Code
tone for CW reception.
CW Transmit L.E.D. This indicator is activated by the CW keying circuit. It flashes
during CW transmission.
The computer then translates these signals into the
RTTY/CW Computer Interface
THE 12VDC AC
1

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Summary of Contents for MFJ MFJ-1224

  • Page 1 RTTY/CW Computer Interface MFJ-1224 RTTY/CW COMPUTER INTERFACE Thank you for purchasing the MFJ-1224 Interface. The MFJ-1224 will allow you to transmit and receive RTTY and CW when used with your transceiver. During reception, the MFJ-1224 converts the CW or AFSK tones from your receiver into computer compatible TTL level signals.

  • Page 2: Back Panel

    BACK PANEL The MFJ-1224 provides inputs and outputs to allow interfacing to nearly any possible combination of computer and transceiver. The back paragraphs below describe their uses. Only a few of the available connections will be used for an given application;...
  • Page 3 MFJ-1224 Instruction Manual RTTY/CW Computer Interface continuation of the negative supply. The loop out merely acts as a spst switch switching the loop current on and off. DIRECT KEYING This output keys rigs requiring direct keying (most rigs with solid state finals).
  • Page 4 MFJ-1224 Instruction Manual RTTY/CW Computer Interface Next is a eight pin general purpose connector which allows you to adapt the interface to almost any computer and software. An internal DIP switch allows the inputs and outputs to be inverted if necessary to correspond 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 received RTTY signal.

  • Page 5: Preliminary Connections

    MFJ-1224 Instruction Manual RTTY/CW Computer Interface AUDIO IN The audio input jack should be connected to the external speaker jack or headphone jack of your receiver with a shielded audio cable. The interface end of the cable requires a RCA type plug.

  • Page 6: Internal Controls

    Caution: Improper adjustments of the internal controls will prevent the interface from functioning. The MFJ-1224 has several internal controls and adjustments, as shown in the diagram and described below. The layout is shown in FIGURE 4. AUDIO OUT GAIN This controls the level of the audio for AFSK output. It is preset at the factory to a reasonable level for most transmitters.

  • Page 7: Computer Operation

    If your radio teletype provides TTL voltages for input and output, you can hook it directly to the MFJ-1224. If not, you will have to use the loop supply circuit and a current loop to the TTL interfaces. (SEE CQ, November 1983, page 49.)
  • Page 8 MFJ-1224 Instruction Manual RTTY/CW Computer Interface MGJ-1224 CONTROL SETTING 1. Set the front panel switches on the MFJ-1224 as shown in Figure 3. 2. Tune the receiver until you hear only noise. 3. Turn the audio gain up to maximum.
  • Page 9 Log the settings of the CONTROL(S) for future reference. Turn the X-TAL CAL OFF. With the controls of the MFJ-1224 set for CW, all Morse Tuning will be made with the VFO. Your transmit signal will appear on the frequency to which the other station is listening.
  • Page 10 ON continuously and the DATA LED is blinking on and off the most pronounced. 1. Set the switches on the MFJ-1224 for RTTY, 170 Hz shift, and NORMAL. (See Fig. 3A.) 2. Set the computer for 60WPM RTTY. Most RTTY on the Amateur HF bands is set at 60WPM, 170Hz shift.
  • Page 11 MFJ-1224 Instruction Manual RTTY/CW Computer Interface 3. Play the tape back into the audio input of the MFJ-1224. 4. Observe the flashing rate of the PHASE LOCK and the DATA L.E.D.s. 5. When the L.E.D. of the PHASE LOCK is on steadily, and the "*" and "U" is occurring on the screen error free, the PLL frequency is at 2210Hz.
  • Page 12 4. If the counter doesn't read 2295Hz, then adjust VR3 (See Fig 4) for a reading of 2295 (+ 2Hz). CALIBRATION OF THE 850Hz SHIFT 1. Set the MFJ-1224 front panel switches for 850Hz shift. 2. Connect a frequency counter as in Calibration of the MARK Frequencies. 3. The frequency counter should read 2975Hz.
  • Page 13 HIGH TONE MFJ-1223 RS-232 INTERFACE The MFJ-1223 is used to connect the MFJ-1224 ports. Since the MF-1224 to uses TTL voltage (+ 5VDC) and RS-232 ports are + 12VDC, an interface becomes necessary to interconnect. Our MFJ-1223 allows the use of the port.
  • Page 14 +5VDC NOT USED II. C-64™ A. Using the MFJ-1265 or MFJ 1253 Software. NOTE: The connector cable supplied with the software has the proper connections for the GENERAL CONNECTION PORT and the C-64™ USERS PORT. The DIP switches are set at the factory for this computer, software, and cable.
  • Page 15 MFJ-1224 Instruction Manual RTTY/CW Computer Interface _____________________________________________________________________ B. Using Kantronics Hamtext™ Software NOTE: The DIP switches must be set for this software as follows: MFJ-1224 "K" Connector Control Port MFJ-1224 DIP Switches DEMOD CW KEY RTTY CW ID _____________________________________________________________________ C. Using the AEA-SOFT and MBA-TEXT, VERSION 1.2 Software...
  • Page 16 MFJ-1224 Instruction Manual RTTY/CW Computer Interface +5VDC NOT USED B. Using Kantronics Hamsoft™ Software NOTE: The DIP switches must be set for this software as follows: MFJ-1224 "K" Connector Apple Game Port MFJ-1224 DIP Switches DEMOD CW KEY RTTY CW ID C.
  • Page 17 +5VDC NOT USED NOTES: 1. A TTL TO RS-232 CONVERTER MUST BE USED WITH THE CLAY ABRAMS SOFTWARE. (We recommend the MFJ-1223.) 2. PLACE A luf ELECTRONIC CAPACITOR FROM PIN 2 (DATA IN) OF THE SERIAL I/O TO GROUND. ™Hamsoft and ™Hamtext are trademarks of Kantronics, Inc.

  • Page 18: Technical Assistance

    If the manual does not reference your problem or your problem is not solved by reading the manual, you may call MFJ Technical Service at 601-323-0549 or the MFJ Factory at 601-323-5869. You will be best helped if you have your unit, manual and all information on your station handy so you can answer any questions the technicians may ask.

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