MFJ Enterprises 9475 Hf Transceiver Instruction Manual

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
1  Introduction
 
 
Congratulations on choosing the MFJ-9475 75-Meter transceiver.  At home or on the 
road, your MFJ-9475 is built to deliver performance you never thought possible from a 
low-power radio.  Before attempting to operate, please read this manual carefully!  Lets 
begin with an introduction to some special features we think youll like! 
 
•
•• •  Easy to Operate:  A back-to-basics radio, the MFJ-9475 is simple to use.  There are 
no...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
2  MFJ-9475 Control Locations and Functions
 
 
 
 
                                 
Mic GainPowerAntenna+ -
12
3 
 
Rear Panel 
 
 1. Power Jack: 5.5 mm OD x 2.1 mm ID, (+) to center pin. 
 2. Antenna Jack: SO-239 for standard coax plug. 
 3. Mic Gain:   Controls speech-amp gain--normal setting 12:00. 
  
 
 
 
 
 
                      
On
OffOn
Off
Mic
Power TuneXmitVolume
Pwr
MFJ 75-Meter SSB Radio
Model MFJ-9475
1
2
3456
7
84.0...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
3  Assembling Your Station
 
 
Youll need three items to put your MFJ-9475 on the air: 
 
Power Supply:  The MFJ-4114 AC/NiCad Portable Power Pack or MFJ-4110 AC. Wall-
adapter Supply are especially designed for the MFJ-9475.  You may also use any other 
regulated 13.8-Volt supply or 10-cell NiCad pack that delivers 2 Amps on peaks (RF 
output slightly lower with 12-volt supplies).  Use a 5.5 mm OD x 2.1 mm coaxial-type 
power plug (Radio Shack...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
4  Operating Your MFJ-9475
 
 
 
                
On
OffOn
Off
Mic
Power TuneXmitVolume
Pwr
MFJ 75-Meter SSB Radio
Model MFJ-9475
4.0
3.75 3.9 3.85
3.8 3.95
 
 
Receiving:  The MFJ-9475 is extremely simple to operate.  To get started, press the 
POWER
 switch on (the green PWR 
LED should illuminate).  Adjust the VOLUME
 control 
for a comfortable listening level.  Now, tune in your station with the VFO TUNING
 knob.  
Thats all there is to it!...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
5  Antennas for your MFJ-9475
 
 
 
 
1/2-wave Dipole
or Inverted-VDipole Length  =  Freq in MHz /468
Inverted-V Length =  Freq in MHz /492
Install balun here
 
 
 
 
The key to success when operating low-power SSB is a properly-installed full-sized 
resonant antenna.  Dipoles and inverted-Vs generally work best for regional coverage. 
 
Typical length for a 75-meter phone-band dipole is around 121 feet.  This length may 
vary somewhat, depending...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
6  Typical Technical Specifications
 
 
Receiver Section: 
  Frequency Coverage    3750 - 4000 kHz  
 Receiver Type   Single-conversion Superhet 
  VFO Frequency    6.0 - 6.250 MHz     
 IF Frequency   10 MHz 
  IF Selectivity      -6 dB @ 2.4 kHz 
  Blocking Dynamic Range   >100 dB  
 Sensitivity   0.3-uV MDS 
  Audio Output      0.75 Watts into 8Ω at 10% THD 
 Receive Current  100 mA 
 
 
Transmitter Section: 
 RF Power Output    12-Watts PEP...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
7  Theory of Operation
  (see Block Diagram) 
 
Receiver:  A four-pole bandpass filter at L1-L2 pre-selects incoming 4-MHz signals.  
Active mixer U1 amplifies and converts signals to 10-MHz using a self-generated 6.0-
6.25 MHz VFO signal.  Crystal ladder SSB filter Y1-Y6 sets message-channel bandwidth 
at approximately 2.4 kHz.  Diode switching routes signals through the SSB filter and IF 
amplifier U2.  U2 provides AGC-controlled IF gain in RX...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
8  Troubleshooting
 
 
Radio Does Not Power Up:  Check the power plug, supply wires, and power source.  
Also, check to see if the REVERSE-POLARITY FUSE
 is open inside the radio.  This 
fuse is etched onto the pc board next to the radios power jack.  If open, replace with a 
2.5-A pigtail type fuse or short length of #36 enamel wire.    
 
No Signals Received:  Check the antenna and feedline.  Is the TUNE
 switch stuck on?  Is 
the band dead??...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
9  Field Alignment Procedures for the MFJ-9475 Transceiver
 
 
These internal adjustments require technical competence and access to accurate lab-type 
test equipment.  If you dont feel qualified to perform these procedures, please let MFJ--or 
a qualified radio service technician--do the work.  Mis-alignment could result in out-of-
band spurious emission (in violation of FCC rules) and poor on-air performance. 
 
Special Tools, Parts, Test...

MFJ-9475 Instruction Manual    75-Meter SSB Travel Radio 
10  Receiver Sensitivity: (Use a calibrated RF-Signal Generator) 
[  ]  Connect a weak 3.900 signal source to ANTENNA 
jack. 
[  ]  Tune in source for maximum S-meter reading using VFO. 
[  ]  Adjust Signal Generator amplitude for S5-S7 meter reading. 
[  ]  Touch up L1, L2, T1, T2 for maximum S-meter reading. 
 
Transmitter Bandpass Filter Alignment: (Use a Watt meter and Dummy Load) 
[  ]  Connect low-power watt meter with dummy-load to the...