MFJ Enterprises MFJ-9420 Instruction Manual

MFJ Enterprises MFJ-9420 Instruction Manual

20-meter ssb travel radio

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MFJ-9420 Installation Manual
20-Meter SSB Travel Radio
INTRODUCTION
Congratulations on your choice of the MFJ-9420 20-Meter transceiver. The MFJ-9420 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-9420 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.
CW ADAPTER AVAILABLE: Install the MFJ CW adapter board jump to the low end to work
CW. Semi-break in keying and sidetone.
At home or on the go, you will enjoy countless hours operating the MFJ-9420. 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 Enterprises MFJ-9420

  • Page 1 CW. Semi-break in keying and sidetone. At home or on the go, you will enjoy countless hours operating the MFJ-9420. 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-9420. 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-9420 Installation Manual 20-Meter SSB Travel Radio TYPICAL SPECIFICATIONS RECEIVER SECTION: Frequency Coverage: 14.150 14.350 MHz (14.000-14.100)* Receiver Type: Single conversion superhet VFO Frequency: 4.150-4.350 MHz (4.000-4.100)* IF Frequency: 10 MHz IF Selectivity: -6 dB at 2.5 KHz AGC: Audio-derived Sensitivity: <.5 uV for 12 dB S/N...
  • Page 4: Theory Of Operation

    MFJ-9420 Installation Manual 20-Meter SSB Travel Radio THEORY OF OPERATION RECEIVER: Four-pole bandpass filter L1-L2 preselects incoming 14 MHz signals. Active mixer U1 amplifies and converts signals to 10 MHz using a self generated 4 MHz VFO signal. Crystal ladder filter Y1-Y6 sets message channel bandwidth (diode switching routes transmit and receive signals through the filter and U2).
  • Page 5: Rear Panel

    MFJ-9420 Installation Manual 20-Meter SSB Travel Radio MFJ-9420 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-9420 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

    STEP 6. To transmit, press the mic's PTT switch and speak at normal conversational level with the mic held about 2 inches from your mouth. The MFJ-9420 has a very potent speech processor and will pick up your voice at full intensity. Avoid the natural temptation to...
  • Page 8 MFJ-9420 Installation Manual 20-Meter SSB Travel Radio SIMPLE 20-METER ANTENNA SUGGESTIONS COAXIAL FED DIPOLES: A wire dipole for the phone band should measure about 32'10" (16'5" per leg). Feed with RG-58U or RG-8X; raise high and in the clear for best performance.
  • Page 9: Troubleshooting

    High power and big antennas have never been a requirement for worldwide radio communication and still are not. Despite the vast distances involved, hams consistently reach every corner of the planet running far less power than your MFJ-9420. How do they do it? Here are some proven tips guaranteed to work: GROOM YOUR ANTENNA Inspect and clean all traps and contacting surfaces.
  • 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-9420. 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-9420 Installation Manual 20-Meter SSB Travel Radio 10.0 10.0 10.0 BIPOLAR AND JFET DEVICES: D/E = Drain/Emitter S/B = Source/Base G/C = Gate/Collector * = Test in TRANSMIT mode ** = Test with TUNE switch depressed *** = DO NOT TEST gate of Q9 may cause generation of parasitic oscillations.
  • Page 13 MFJ-9420 Installation Manual 20-Meter SSB Travel Radio SCHEMATIC...
  • Page 14 MFJ-9420 Installation Manual 20-Meter SSB Travel Radio...

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