MFJ MFJ-1275, MFJ-1275M, MFJ-1275T User Manual

SOFTWARE CONSIDERATIONS

SHAREWARE

The CD that comes with your MFJ-1275/1275M/1275T contains shareware. This CD will automatically run the MFJ Sound Card Interface Software Installation Menu upon startup. If, for some unforeseen reason, your CD does not automatically run you must manually invoke it. To do this, follow the steps listed below.

1. With the Shareware CD in the CD drive, click on the Start button at the bottom left of the screen.

2. Click on RUN. This will bring up a command window.

3. Click the Browse button.

4. When the browse window is open, double click on the CD drive.

5. Double click on the autorun.exe program.

6. The autorun.exe program will now show up in the command window.

7. Click OK and the MFJ Sound Card Interface Software Installation Menu will begin to run.

From the menu, you may choose which shareware program(s) to install. Though effective, this software is limited in its uses. To get the full experience with your unit, MFJ recommends that you purchase either the MFJ-1296 or the MFJ-1298 Sound Card Program.

The sound card programs on the provided CD are as we said before, “SHAREWARE”. If there are problems with the software, then you need to contact the author of the program that you are trying to use. MFJ Enterprises provides only limited support for these shareware programs.

MFJ-1296 & MFJ-1298 SOFTWARE PACKAGES

The MFJ-1296, RadioCom4, and the MFJ-1298, RadioCom5, are the best programs for soundcard interfaces and amateur radio.

Some features of the MFJ-1296 and the MFJ-1298 include:

• PSK: Supports PSK-31, Q and B PSK

• SSTV: 32-bit color, supports all SSTV formats, screen sizes/SSTV parameters are all variable.

• FAX: Supports AM/FM bands. Includes Weather FAX and satellite FAX direct. Supports

ICO 267, 288, 352, and 567. RPM 48, 60, 90, 120, 180, and 240. FAX resolution is up to 1810 dpi, FAX features IOC and slant-correction. FAX pictures can be saved, printed, retransmitted.

• CW: Features automatic speed tracking, DSP notch and bandpass filters.

• RTTY: Supports all standard shifts and speeds. X/Y scope and frequency spectrum display

makes tuning RTTY a breeze. Also supports NAVTEX, European SYNOP, Baudot, and Sitor-B.

• Radio control for over 80 radios.

• DSP Audio Filters and Analyzer.

• RS-232 Level Converter.

The MFJ-1298 has additional features that include Spectrum Analyzer, Dual Scope Display, Sound Recorder, Time/Frequency Management, Frequency Analyzer, 3-D Scanner, Satellite Tracking, and much more!

The MFJ RadioCom requires a computer with a minimum 200 MHz, Pentium/Celeron processor, at least 64 MB of RAM, and Microsoft ®Windows95/98/ME/2000/NT/XP operating system.

These fully integrated software packages can be purchased from MFJ and are fully supported by MFJ.

MFJ-1275/1275M/1275T Instruction Manual Sound Card Radio Interface

TABLE OF CONTENTS

Introduction ...........................................................................................................................2

1.0 Powering the MFJ-1275/1275M/1275T..............................................................................3

2.0 Connecting the MFJ-1275/1275M/1275T........................................................................... 3

3.0 MFJ-1275T Special Instructions........................................................................................ 4

4.0 Microphone and Radio Connections (MFJ-1275/1275M) ..................................................5

4.1 Internal Header and Jumper Connection Description............................................5

4.2 Jumper Diagrams (MFJ-1275/1275M)................................................................... 6

4.3 Customizing Internal Jumpers (MFJ-1275/1275M)................................................ 9

4.4 Audio Termination Jumpers (JMP1, JMP2).......................................................... 10

5.0 Rear Panel Connections.................................................................................................... 10

5.1 Computer RS-232 port.........................................................................................10

5.2 Radio ................................................................................................................... 10

5.3 Computer.............................................................................................................11

5.4 GND.....................................................................................................................11

6.0 Operating Suggestions......................................................................................................11

6.1 Placement of this Unit ..........................................................................................11

6.2 Hum, Squeals, and Distortion...............................................................................11

6.3 Operating Adjustments.........................................................................................12

6.4 Monitoring Receiver (SSTV, Voice Keyer) ..........................................................13

7.0 Software...........................................................................................................................13

8.0 Troubleshooting Guide.....................................................................................................13

9.0 Technical Assistance.........................................................................................................14

10.0 Schematic .......................................................................................................................15

MFJ-1275/1275M/1275T Instruction Manual Sound Card Radio Interface

INTRODUCTION

Thank you for purchasing the MFJ-1275/1275M/1275T) Sound Card Radio Interface. The MFJ1275/1275M/1275T was designed for use in all sound card to radio applications. Great care was taken to make sure hum, noise, and distortion are minimized or eliminated, insuring the best possible signal from your equipment.

Before attempting to use the MFJ-1275T, please read section 3.0. Before attempting to use the MFJ1275/1275M, please read section 4.0. This section contains important information about interfacing the MFJ-1275/1275M with your transceiver. We will start with a brief introduction into the special features that make your Sound Card Radio Interface an important addition to any computer station.

MFJ-1275/1275M/1275T Features:

Serial Port: This port allows the computer to control the push-to-talk of your radio and the microphone push-to-talk switch to override and/or interrupt your computer’s transmission.

Microphone/Radio plug-in jumpers: Internal jumpers program microphone wiring for any brand or model of radio with the appropriate 8-pin connector. There is no need to solder tiny plugs and wires or purchase adapters.

PTT Message Interrupt/Stop: Microphone PTT (push-to-talk) switch automatically halts outgoing messages when using software that allows external com-port interrupts. Even if software does not allow interrupts, you can still hold the microphone PTT to stop digital transmissions and transmit microphone audio.

Radio/Speaker-Computer/Speaker switching: This transfers audio lines with a touch of the ON/BYPASS switch. No need to move cables every time you change use of the computer or radio. NOTE: Requires you use external speaker on radio.

Off-Air Recording: Capture signals from your receiver's audio jack for review or replay, or use with spectrum analyzer programs.

RFI Proof Circuitry: RF suppression and line isolation virtually eliminates RF feedback, hum, and distortion. An isolation transformer prevents audio ground loops.

Level controls: Two level controls, one for transmitter drive and one for receiver-to-sound card drive level. No need to adjust microphone gain or sound card level settings every time you change modes.

Stereo or Mono Audio input: A front-panel switch selects left, right, or both sound card audio output channels.

Rugged Construction: A solid all aluminum cabinet and sturdy surface-mount construction gives the MFJ-1275/1275M/1275T mechanical and electrical durability.

MFJ-1275/1275M/1275T Instruction Manual Sound Card Radio Interface

1.0 POWERING THE MFJ-1275/1275M/1275T

External Power: Use any well filtered power source capable of supplying 12-15 Vdc at 100 mA. The minimum operating voltage is 10 Vdc. Under a full load, sources exceeding 16 Vdc may permanently damage this product. The external power jack, of the Sound Card Radio Interface, accepts a standard

2.1mm coaxial power plug. The power plug's center pin must be positive (+) and ground-isolated. The outer shell is negative (-) and may be grounded or floated at the supply. When connecting to a high current supply (more than one ampere), we strongly recommend fuse protecting both positive and negative supply leads with ½ ampere to 1 ampere fast-blow fuses.

1-A

Power Supply+

WARNING: Never insert the power plug with power applied—an accidental short from (+) to

chassis ground may result. Also, never allow the MFJ-1275/1275M/1275T supply voltage to exceed 16 Vdc. Connections to high current power sources must be fuse protected!

MFJ-1312D Power Supply: The MFJ-1312D wall adapter is also suitable for powering your Sound

Card Radio Interface. It comes with the correct 2.1mm power plug installed, and is available directly from MFJ Enterprises, Inc. or through your local MFJ dealer.

2.0 CONNECTING THE MFJ-1275/1275M/1275T

FRONT PANEL:

MICROPHONE Accepts standard 8-pin microphone plug (8-pin modular for the

MFJ-1275M) (4-pin for the MFJ-1275T)

INPUT

Selects left, both, or right sound card audio channel

MANUAL/VOX ON/BYPASS Selects computer audio and control (ON) or normal operation of

XMIT Illuminates when computer transmitting or ready to transmit

POWER MONITOR/OFF Allows the user to listen through the radio speakers while at the

Selects PTT control from COM port or VOX operation

computer and radio (BYPASS)

(VOX) with audio input Illuminates when unit is in ON mode

same time being routed through the Sound Card Radio Interface

MFJ-1275/1275M/1275T Instruction Manual Sound Card Radio Interface

REAR PANEL:

POWER

Requires 12-15 Vdc @ 100mA (16 volt absolute maximum)

COMPUTER RS-232

DB-9 female serial (COM port) connection

RADIO

TO EXT SPKR 3.5mm mono jack connects to station loudspeaker or other audio

accessories normally connected to radio speaker jack

TO RADIO MIC

3.5mm mono jack connects to external speaker output of radio

COMPUTER

TO SOUND CARD AUDIO IN

TO EXT SPKR FROM SOUND

CARD AUDIO OUT GROUND

3.5mm mono jack connects to sound card input

3.5mm stereo jack connects to computer speaker

3.5mm stereo jack connects to sound card output Ground terminal to station's ground buss (see section 5.4)

3.0 MFJ-1275T SPECIAL INSTRUCTIONS

The MFJ-1275T is a special interface unit modified for use with Ten-Tec and other radios using four-pin microphone connectors. Most four-pin connector systems use the microphone shield as a ground return for push-to-talk lines.

Use of audio shields as a control or PTT grounds causes audio systems to be much more susceptible to ground loop hum and noise, that is why most modern radios maintain separate PTT and audio ground leads. When using a common audio and PTT ground, we must be much more careful with external connections.

Please follow these basic system guidelines:

1.) Always ground the rear cabinet ground lug of the MFJ-1275T directly to the radio’s rear- chassis ground. This will allow control signals and any undesired hum or noise to flow through the rear panel chassis ground connection and reduce hum and noise in the audio connections.

2.) Never make any ground connection at HD1 in the MFJ-1275T. This will force any control system grounds to use the rear panel chassis ground connections, keeping the microphone shield clear of any unwanted hum and noise.

3.) Always connect the computer and radio AC power cords to the same outlet or outlet strip. This will minimize voltage differences between the computer and radio chassis, reducing unwanted ground loop currents.

4.) Locate the MFJ-1275T near the radio. This will allow use of shorter ground connections and shorter microphone cords, reducing the resistance of the audio system shields.

5.) Ground the computer to the station ground buss if possible. This will ensure computer cabinets and radio cabinets are all at the same potential, and reduce unwanted hum and noise.

MFJ-1275/1275M/1275T Instruction Manual Sound Card Radio Interface

Ten-Tec and KENWOOD 4-Pin Microphone Setup: TS-120S, 130S, 180S, 511S, 520S, 530, 600, 700

TS-820, 830, TR-7200A, 7400A, 7500

This diagram may cover some other radios in the KENWOOD product line with 4-pin round microphone jack.

If there are any Questions concerning the information provided, please refer to your RADIO NSTRUCTION MANUAL.

MFJ is neither liable nor responsible for any mistakes or errors in the information provided.

Receive Audio is taken from the External Speaker output or some other speaker level audio source.

Special Notes for Ten-Tec Radios:

When using Ten-Tec radios, avoid using the station’s 13.8-volt dc power source to power the MFJ-1275T Sound Card Interface. Always use the MFJ-1312D, or equivalent power adaptor!

4.0 MICROPHONE AND RADIO CONNECTIONS (MFJ-1275/1275M)

Different manufacturers and different radios may wire the same style connectors differently. The MFJ1275/1275M has internal headers that use small moveable jumpers. The MFJ-1275 uses common round 8-pin microphone connectors found on most transceivers. The MFJ-1275M comes with a modular microphone jack (like telephones might use). The MFJ-1275T uses a round 4-pin for Ten Tec.

Internal jumpers are used to program connections for any radio that connects to the prewired connectors. This feature eliminates the need for soldering jacks or purchasing adapter cables. The MFJ-1275/1275M must be configured using the internal jumpers before use (see section 4.1 and 4.2). The MFJ-1275T comes ready to use with your Ten Tec rig.

The microphone/radio setup procedure requires a few minutes of time. Before you start, you will need the manual of your radio readily available.

4.1 INTERNAL HEADER AND JUMPER CONNECTION DESCRIPTION

This section is for the MFJ-1275 and MFJ-1275M only. The jumpers in this unit are grouped by connection type, with all eight-microphone pins in a row. The connection blocks are:

HD1 Chassis ground HD2 Audio ground (NOT the same as chassis ground) HD3 Pass through, jumper all connections except microphone audio (HD4, HD7) and push-to-talk

lines (HD5, HD6)

HD4 Audio from microphone HD5 PTT line to radio HD6 PTT from microphone HD7 Microphone audio output to radio

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