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MFJ-9475 Installation Manual
75-Meter SSB Travel Radio
INTRODUCTION
Congratulations on your choice of the MFJ-9475 75-Meter transceiver. The MFJ-9475 is
specially designed to deliver performance you never thought possible from a low power radio.
Please read this manual carefully before attempting to operate your new radio. Lets begin with
an introduction to some special features we think you'll like!
FEATURES
EASY TO OPERATE: The MFJ-9475 is an easy-to-operate," back to basics" radio. Operate the
unit with ease in minutes!
GREAT SENSITIVITY: Quiet DBM front end and lots of overall gain for great sensitivity. If
the signal is there, you will hear it!
ANALOG S-METER: Adjust the tuner or aim the beam with pinpoint accuracy. A calibrated
analog S-Meter measures even the smallest variations in signal strength.
The meter also
monitors your speech processing level on transmit.
EXCELLENT SELECTIVITY: Sharp ladder filter cuts adjacent chatter and focuses transmitter
power where you need it most for great selectivity.
SMOOTH, STABLE VFO: Effortless tuning with custom manufactured 8:1 reduction drive ball
bearing VFO tuning capacitor provides smooth and stable VFO. Fine Tune lets you zero-in
smoothly.
POWERFUL AF OUTPUT: Big audio and powerful AF output even in noisy locations from a
special Philips BTL audio chip and rugged 3" speaker.
FULL-TIME RF SPEECH PROCESSING:
Commanding speech cuts through QRM and
competes with radios running far more power. Compare with your 100-watt rig. You will be
amazed by the signal reports!
TRAVEL LIGHT: Packs the same punch as 50-Watt radios without the heavy 10 Amp power
supply! Designed to run on NiCd's or the ultra light MFJ-4110 AC wall adapter supply.
RUGGED TRANSMITTER: Bullet-proof Motorola PA transmitter runs cool, and tolerates 3:1
VSWR accidentally opened feedlines or feedline shorts.
MADE TO LAST: Conservative design, with a premium plate through pc board, quality
components, handsome brushed aluminum panel, and a tough vinyl clad case ensure years of
dependable service.
At home or on the go, you will enjoy countless hours operating the MFJ-9475. Best of all, it is
fully backed by MFJ's exclusive "No Matter What" 1 year guarantee. If it breaks, we will take
care of it!

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Summary of Contents for MFJ MFJ-9475

  • Page 1 At home or on the go, you will enjoy countless hours operating the MFJ-9475. Best of all, it is fully backed by MFJ's exclusive "No Matter What" 1 year guarantee. If it breaks, we will take...
  • Page 2: Quick Start Instructions

    1. POWER SUPPLY: The MFJ-4114 AC/NiCd Portable Power Pack or MFJ-4110 AC wall- adapter supply are Especially designed to run the MFJ-9475. You may also use any 13.8 Volt supply or 10-cell NiCd pack as long as it delivers 2 A on peaks (12 Volt supplies will work fine but at reduced RF output).
  • Page 3: Typical Specifications

    MFJ-9475 Installation Manual 75-Meter SSB Travel Radio TYPICAL SPECIFICATIONS RECEIVER SECTION: Frequency Coverage: 3.750 to 4.000 MHz Receiver Type: Single conversion superhet VFO Frequency: 6.000 - 6.250 MHz IF Frequency: 10 MHz IF Selectivity: -6 dB at 2.5 KHz AGC:...
  • Page 4: Theory Of Operation

    Q3/Q4 and U2. Syllabic compression of the speech waveform optimizes average transmitter output power. The MFJ-9475 is especially designed to operate from lightweight constant current power sources such as NiCd cells or the MFJ wall adapter AC supply.
  • Page 5: Rear Panel

    MFJ-9475 Installation Manual 75-Meter SSB Travel Radio MFJ-9420/40/75 CONTROL LOCATION AND FUNCTION MFJ ENTERPRISES, INC. ANTENNA STARKVILLE, MS USA INPUT POWER 12-15VDC GAIN 1.2 AMP REAR PANEL 1. POWER JACK: 5.5mm OD, 2.1mm ID, (+) to center pin. 2. ANTENNA JACK: SO 239 for standard coax plugs.
  • Page 6 12 15 volts at 2 Amps (13.8V required for full RF output). The DC power connector at the rear of your MFJ-9475 is a 5.5mm OD, 2.1mm ID coaxial type jack. Extra plugs are available from RadioShack stores (#274-1567). Always connect plus (+) to the CENTER PIN.
  • Page 7: Special Operating Notes

    RF signal for final adjustment. Red XMIT indicator should light. STEP 5. The VFO tuning range covers 3.750 to 4.000 MHz and the MFJ-9475 tuning dial was carefully calibrated at the factory. However, by nature an analog frequency readout may be subject to some inaccuracy or misinterpretation.
  • Page 8 INJURY OR DEATH! GETTING THE MOST FROM YOUR MFJ-9475 STATION: While spanning the globe with a small portable rig like the MFJ-9475 may SOUND difficult, it really is not -- many DX-window trans-Atlantic contacts have been made using these radios.
  • Page 9: Troubleshooting

    QRM. Do not be shy about calling. The MFJ-9475 has very potent audio and on air tests indicate its signal is competitive with 100-Watt radios. If your antenna is good, most stations won't even...
  • Page 10 If these checks don't uncover the problem, or if you do not feel qualified to make the prescribed adjustments, please call us for help at 800-647-TECH (800-647-8324). FIELD ALIGNMENT PROCEDURES FOR THE MFJ-9420 TRANSCEIVER SPECIAL TOOLS, PARTS, TEST EQUIPMENT: AC Power Supply, 13.8 Volts @ 2 Amps...
  • Page 11 *If reverse polarity track fuse opens, install a miniature 2.5 A pigtail fuse or a 3/4" hair pin loop of #32 wire. DC VOLTAGE CHART TROUBLESHOOTING GUIDE For advanced troubleshooters, the following are typical DC voltages found in the MFJ-9475. Voltages were checked with handheld probe type DVM to minimize effects of lead inductance and to limit the potential for RF feedback.
  • Page 12 MFJ-9475 Installation Manual 75-Meter SSB Travel Radio SCHEMATIC...
  • Page 13 MFJ-9475 Installation Manual 75-Meter SSB Travel Radio...

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