MFJ Enterprises Mfj-9410 10 Meter Ssb Transceiver Instruction Manual

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
1 
INTRODUCTION 
 
Congratulations on your choice of the MFJ-9410 Ten-Meter SSB Transceiver.  Please 
read this manual carefully before attempting to operate your new radio.  Lets begin with 
an introduction to some special features we think youll like! 
 
Easy to Operate:  No microprocessor mumbo-jumbo.  Just turn on and tune in! 
 
Potent Signal:  20-Watt PEP--plus Constant Current
TM syllabic speech processing for an 
added 4 to 6-dB advantage to cut through noise, fading, and QRM. 
 
Low Drain:  Operate from a 3-Amp AC supply or 12-Volt battery.  All-analog circuitry 
means highest energy efficiency! 
 
Hot Receiver:  Low-noise preamp and active-DBM front end dig deep into the noise to 
capture weak ones.  If the signal is there, youll hear it. 
 
Excellent Selectivity:  Sharp 2.3 KHz SSB ladder filter reduces passband noise, fights 
QRM, and improves intelligibility. 
 
TVI Protection:  Built-in 7-element lowpass filter knocks down TVI--lets you operate 
day or night, when you want to! 
 
Real S-Meter:  Steer your beam with pin-point accuracy and give meaningful reports 
with a full-sized analog S-meter.  Also, monitor speech processing level. 
 
Agile Tuning:  No unexpected tuning-rate shifts or stair-stepping.  Reduction-drive 
analog VFO lets you scan the band for signals quickly, then zero in smoothly.  Best VFO 
for hunt-and-pounce contest operation! 
 
Loud Audio: Efficient rugged 3-1/2 top-mount speaker delivers robust audio, 
overcomes ambient noise. 
 
Phone Jack: 1/4 jack accepts standard stereo headphones, cuts off speaker 
automatically.  Attenuated output protects phones and ears, makes gain adjustment easy.  
 
Amplifier Jack:  Solid-state FET switch keys external amplifiers. 
 
Built to Last:  Conservative design, premium-quality plate through PC board, quality 
components, handsome brushed-aluminum panel, and tough vinyl-clad case make for 
years of dependable service. 
 
At home or traveling the world, youll enjoy superb 10-meter performance with your 
MFJ-9410.  Best of all, its fully backed by MFJs exclusive NO MATTER WHAT
TM one-
year guarantee.  If it breaks, well take care of it.  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
2 
GENERAL DESCRIPTION 
 
The MFJ-9410 is a 20-Watt PEP USB transceiver designed especially for fixed or 
portable radio communication in the ten-meter amateur band.  Energy-efficient analog 
circuitry and syllabic speech processing deliver superior on-air performance while 
conserving valuable power.  The MFJ-9410 uses a single-conversion mixing format and a 
low-noise heterodyne VFO for enhanced weak-signal performance.  The transmitter 
features a built-in 7-element lowpass filter to reduce interference at TV and FM-broadcast 
entertainment frequencies.  Other features include a sharp HF-communication grade 
crystal, IF bandpass filter, built-in heavy-duty speaker, fully-analog mechanical S-meter, 
optional semi-break-in CW module, and intuitive easy-to-operate controls. 
 
Typical Specifications 
 
Receiver Section: 
 
Frequency Coverage: ..................................... 28.300-28.600 MHz 
Mode: ............................................................ USB 
Receiver Type: .............................................. Single-conversion Superhet 
Frequency Control: ........................................ Crystal mixed heterodyne VFO 
IF Frequency:................................................. 10 MHz 
IF Selectivity: ................................................ -6 dB @ 2.3 KHz 
AGC: ............................................................. Audio-derived, 70-dB dynamic range 
Sensitivity:..................................................... .15 uV for 12-dB S/N 
Audio: ............................................................ 500 mW into 8 Ohms at 10% THD 
Average RX Current:..................................... 60-mA, (S-meter lamp disabled) 
 
Transmitter Section: 
 
RF Power Output:.......................................... 20-Watts PEP 
Mode.............................................................. USB* 
VSWR Tolerance: ......................................... 3:1 VSWR maximum 
Peak TX Current: .......................................... 3.2 Amps 
Speech Enhancement: ................................... RF-compression, syllabic rate 
Spurious Attenuation:.................................... -60 dBc  
Mic Input: ...................................................... 600-Ohm dynamic 
 
*CW operation is possible within the 28.3-28.6 tuning range with an optional CW adapter board. 
  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
3 
QUICK-START OPERATING INSTRUCTIONS 
 
• 
Power Supply:  Use any regulated 13.8-Volt 3-Amp supply or comparably-rated 12-
Volt battery.  Connect power via a 5.5 OD x 2.1 mm coaxial power plug (Radio Shack 
274-1569): 
 [+] lead must be attached to the connector center pin. 
 
+
-
 
 
• 
Microphone:  The MFJ-290 dynamic microphone compliments your radios speech 
processor, but other 600-ohm PTT microphones may be used with a 5-pin DIN 
connector installed as shown below (use Radio Shack 274-003).  Amplified 
microphones should not be used with the MFJ-9410. 
 
1
4
253 Pin 3 = PTT Line
Pin 4 = Mic Line
Pin 1,2,5 = Ground
Mic
PTT
Gnd
 
 
•
•• •  Antenna Selection:  Use any vertical or horizontal 10-meter antenna exhibiting a 
VSWR of 2:1 or less.  A simple dipole or groundplane is adequate for casual 
operation, but a 3-element yagi or 2-element quad yields better DX performance. 
 
Important Note:
  Avoid using antennas with unknown or high VSWR.  The MFJ-9410 
does not provide automatic high-VSWR shutdown circuitry.  Operation into extremely 
reactive loads may result in out-of-band spurious emissions in violation of FCC rules! 
 
•
•• • Speech Processing:  The MFJ-9410 processor rapidly readjusts transmitter IF gain for 
each spoken syllable.  For best results, hold the Mic about 1 from your lips and speak 
normally.  The S-meter should deflect 1/2 scale as you speak. 
 
Important Note:
  Transmit meter deflection will be affected by high-VSWR loads.  If the 
meter deflects beyond S9 or holds below S4 with normal speech, check your antenna.  
A VSWR of 2:1 or less is normally considered acceptable for amateur service. 
 
•
•• •  Connecting a Power Amplifier:  The MFJ-9410 provides a built-in FET switch to 
key an external amplifier.  Be sure to follow all manufacturers instructions carefully 
when installing an amplifier at your station.  The Ext Amp jack provides closure to 
ground during transmit. 
 
•
•• •  Choosing an Operating Location:  Set your station up in a sheltered and dry location.  
Avoid operating in direct sunlight--the radios black case may absorb excessive heat 
that can impair normal operation or damage internal components. 
  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
4 
MFJ-9410 CONTROL LOCATIONS AND FUNCTION 
 
OFFMIC
TXKEYVOLUME MODEL MFJ-9410
28.3
28.4
28.5
28.6
1
2
34
58
FINE
TUNE
76
 
 
Front Panel 
 
1. S-METER:  Measures signal strength on receive, ALC on transmit 
2. POWER SW: Applies DC power to the radio. 
3. MIC JACK: Accepts
 5-pin DIN connector for PTT microphone. 
4. TX LED:   Illuminates when transmitter is keyed. 
5. KEY JACK:  Accepts telegraph key--only used with CW adapter module. 
6. VFO TUNE: Tunes in stations, indicates operating frequency. 
7. VFT:   Fine tune control for precise SSB tuning. 
8. VOLUME:   Adjusts listening level. 
 
 
 
MFJ Enterprises, Inc
Starkville, MS USA
Mic Gain
Ext Amp  PwrAntenna
34
Phones5
2
1
 
 
Rear Panel 
 
1. MIC GAIN: Adjusts speech-amp gain (normal setting 12:00). 
2. EXT AMP:  Accepts RCA plug--keys external linear amplifier.
 
3. POWER JACK:  Accepts 5.5mm OD x 2.1mm ID plug, [+] to center pin (+13.8V/3A). 
4. ANTENNA:  Accepts PL-259 for 50-Ohm coaxial line. 
5. PHONES:    Accepts 1/4 stereo headphone jack. 
  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
5 
TEN-METER ANTENNA SYSTEMS 
 
The better your antenna system works, the more youll enjoy using the MFJ-9410.  Here 
are some general tips for getting top performance: 
 
•
•• • Antenna Selection:  Dipoles, ground-planes, and converted CB antennas all provide 
good performance for casual operation.  However, for serious DX hunting, a compact 
3-element yagi or 2-element quad will yield significantly better results.  Many compact 
directional antennas are small and light enough to roof-mount on a standard TV rotor 
using readily-available TV hardware.  If possible, avoid using low-efficiency 
compromise antennas.  Never operate into an antenna with unknown or high VSWR. 
 
•
•• •  Making a Dipole:  A simple 10-meter dipole cut for 28.4 MHz will be approximately 
16 5-1/2 long.  To prevent feedline radiation and reduce unwanted noise pickup, 
make a simple choke balun at the center by coiling up a short length of the coax and 
securing it with electrical tape or tie-wraps. 
 
16  5-1/2
Choke Balun: 4-5 feet of feedline 
coiled in 6-8 turns.
 
 
•
•• • Antenna Location:  Mount your antenna as high and in-the-clear as possible, but 
remember to factor in feedline loss.  A chimney-mounted antenna at 40 with a short 
low-loss feedline may actually out-perform one mounted 20 higher with a long lossy 
feed.  Be sure to isolate your antenna from other larger antennas or RF-reflective 
metallic surfaces that may distort its normal radiation pattern. 
 
•
•• • Coax Cable:  For runs to 60, RG8X (or mini-8) works well at 28-MHz.  For longer 
runs, or when running a high-power amplifier, use larger-diameter low-loss cable such 
as RG8 foam or RG213.  Seal all exterior connectors against moisture with silicon 
grease, rubber tape, or premium-quality electrical tape. 
 
•
•• • Rotor:  Many TV-type rotors will handle a short-boom 10-meter beam or quad.  
However, long-boom or stacked arrays will require a heavier rotor designed especially 
for amateur radio use. 
 
•
•• • Safety Tips:  When installing antennas, make sure someone is available to assist you 
in an emergency.  Also, avoid any location where your antenna could fall and contact 
power wires.  For catastrophic lightening protection, permanently ground the mast and 
coax shield outside the building with a good ground rod system.  Also, remember to 
disconnect the feedline from your radio at the first sign of severe weather.  Even 
nearby strikes may damage sensitive receiver components with the antenna connected. 
 
THEORY OF OPERATION
  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
6 
 
General:  The MFJ-9410 is a 20-Watt PEP USB transceiver that tunes from 28.3-28.6 
MHz.  The radios single-conversion format uses a high-frequency heterodyne VFO for 
superior stability, low phase noise, and circuit simplicity.  The MFJ-9410 is designed for 
fixed or portable operation from light-weight power sources and uses all-analog circuitry 
throughout for reduced power consumption. 
 
Receiver:  A four-pole bandpass filter (L1/L2) pre-selects incoming 28 MHz signals and 
Q1 provides LNA gain ahead of the mixer.  Operating frequency is controlled by a 38-
MHz heterodyne VFO driving active mixer U1.  The mixer then down-converts 28 MHz 
signals to the radios 10-MHz IF.  A six-crystal SSB ladder filter (Y1-Y6) establishes the 
radios 2.3 KHz message-channel bandwidth.  Gain of IF amplifier U2 is controlled by 
audio-derived AGC.  Product detector U3 demodulates incoming SSB using a 10-MHz 
BFO signal generated by the mixer chips oscillator section.  Recovered audio is fed to 
preamp U4a, which simultaneously drives AGC amp Q3/Q4 and AF-power amp U5.  
Switch Q2 sets the AGC time constant for TX and RX modes. 
 
Transmitter:  Mic-amp U4b drives balanced modulator U7.  Modulator LO is derived 
from the BFO section of U3.  DSB generated by U7 is routed to the IF filter (Y1-Y6) 
where the lower sideband is removed.  IF-amplifier U2 compresses the USB signal at a 
syllabic rate and routes it to transmit mixer U8.  At U8, the 10-MHz IF signal mixes with 
38-MHz VFO energy for conversion to 28 MHz.  The signal is then amplified by driver 
stages Q10 and Q11.  Interstage matching and 28-MHz passband filtering are provided by 
tuned-transformers T4-T6.  PA-stage Q12 is a self-ballasted emitter-tab device operating 
in single-ended class AB.  Input and output ports are matched by L-networks, and a 
seven-element low-pass filter reduces harmonic and spur content of the amplified signal.  
A RF-envelope detector samples signal amplitude and provides feedback to IF-amplifier 
U2 for speech processing.  PTT switch Q9 drives T/R relay K1. 
 
Heterodyne VFO:  VFO mixer U6 combines 6.3-6.6 MHz tunable-oscillator energy with 
a 32-MHz crystal-controlled signal generated by Q6.  Bandpass filter L6-L7 admits the 
38.3-38.6 MHz mixer product to FET-follower Q7, where it is transformed to a low 
impedance and distributed to mixers U1 and U8. 
 
Regulation and Protection:  Adjustable monolithic voltage regulator U9 provides 10.5 
Volts for most low-level stages in the transceiver.  Regulator U10 supplies 5 Volts to the 
mixing VFO.  A diode/fuse crowbar circuit protects the radio against accidental reverse-
polarity damage. 
 
Amplifier Keying:  FET switch Q13 provides a ground-path closure for the purpose of 
keying an external 28-MHz linear amplifier.
 
  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
7 
MFJ-9410 BLOCK DIAGRAM 
 
U1
REC 
MXR
XTAL
FILU2
IF AMP
AGC Y1-6U3
PROD
DETQ5
GATEU4A
AF
PREAMPVOL
U5
AUDIO
AMP
AGC/ALC
AMP
Q2,3,4 M Q1
LNA
BPF
Q9
T/R
LPF
U7
BAL
MODQ8
GATEU4B
MIC
AMPQ7
FLRU6
VFO
MXRQ6
OSC BPF
Q12
PAQ11
DRIVERQ10
PRE
DRIVEU8
TRANS
MXR
ANT
TUNE
VFTU9
REG
10.5VU10
REG
5V
Q13
EXT
SW
 
 
MFJ-9410 INTERNAL ADJUSTMENTS
  (see pictorial on next page)
 
 
[1] Voltage Regulator:  Adjust V-REG trimpot R78 for 10.5V on tab of U9 [18]. 
[2] RSSI Threshold:  Adjust AGC trimpot R11 for 4.3 V at RSSI test point [16]. 
[3] Meter Zero:  Adjust M-ZERO trimpot R17 for zero meter reading--no signal. 
[4] IF Transformers:  Peak IF cans T1,T2 for maximum receiver sensitivity. 
[5] RF Transformers:  Peak RF coils L1, L2 for maximum receiver sensitivity. 
[6] BFO:  Set BFO trimcap C30 so close-in filter peak corresponds to 600 Hz beat note.* 
[7] VFO Cal:  Tune signal generator and VFO to 28.4 MHz, set L3 for zero beat. 
[8] Mixing VFO:  Tune OSC coil L5 and filter coils L6,L7 for maximum RX sensitivity. 
[9] Carrier Balance:  Carefully adjust BAL trimpot R57 for minimum carrier.** 
[10] Mic Gain:  Set for preference--12:00 position is factory default. 
[11] PA Bias:  Attach 200-uA meter at [15], Set bias pot for 20-25 uA reading. 
 
Note
:  To adjust [12 & 13], install a shorting plug at [14] to insert carrier.  Also, turn 
ALC trimpot (R73) clockwise to disable ALC line (should be no meter deflection 
on TX). 
 
[12] Exciter tune: Key Mic and peak C89, C96, C99 for maximum RF output. 
[13] PA:  Key mic and peak C103, C110, C111 for maximum output--then remove plug. 
[14] Carrier Insert:  Shorting plug location to insert carrier for tuning transmitter. 
[15] IC Test Points:  Connect 200-uA meter here to set PA idle current (see above). 
[16] RSSI Test Point:  Used when setting RSSI trimpot [2]. 
[17] ALC Level:  Key Mic and speak, adjust ALC trimpot for 1/2-scale meter deflection. 
[18] V-REG Test Point: Set V-REG trimpot [1] for 10.5-V DC reading on regulator tab. 
 
*Caution--may unbalance carrier, step requires special skill and knowledge to perform. 
**If R57 alone does not produce deep null, interactively adjust R57 and T3 for best null.  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
8 
INTERNAL ADJUSTMENT LOCATIONS 
 
WARNING:  The tune-up information provided in this manual 
does not constitute a step-by-step guide for 
aligning the MFJ-9410.  IF YOU LACK THE TEST 
EQUIPMENT, KNOWLEDGE, AND SKILLS TO ALIGN HF SSB 
TRANSCEIVERS, DO NOT ATTEMPT TO MAKE THESE 
ADJUSTMENTS ON YOUR OWN!!  Far better to contact 
the MFJ factory for assistance.  Mis-alignment may 
cause permanent damage to your unit, and may 
result in interference to other radio services in 
violation of FCC rules.  MFJ cannot be held 
responsible for the performance of radios that 
have been improperly tampered with or mis-adjusted 
by owners and users. 
 
CARRIER
CARRIER
INSERT
L1
L2 T1T2 T3 MIC GAIN
RSSI V-REG
ZERO PA OUTPUT
INPUTPA
DRIVER
PRE-DRIVEALC
VFO CAL
MIXERMXR OSC
VFTVOL VFO TUNE KEY
TX
MIC PWRPWR EXT AMP
PA BIAS
1
2 3
45
6
7 8
9
10
11
12 13
14
1517
16
BFO
TP M
MXR FILBAL MOD
RX IFRX/TX IF
RX RF
LEVELNULL
18
 
 
Note
:  For trimpots, trimcaps, and IF cans (T1-T3), use a non-conductive tuning wand 
with a metallic tip.  For TOKO brand inductors, use a non-conductive wand with a 
narrow plastic tip.  For Coilcraft brand inductors, use a small hex-head non-
metallic tuning tool.
 
 
IN CASE OF DIFFICULTY
 
  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
9 
! Radio does not power up:  Check power plug and power supply.  Also, reverse-
polarity protection fuse may be open (etched on PC board in front of power jack J3).  If 
open, install a 3.0-A pig-tail replacement fuse or short length of #32 wire. 
!  No signals received:  Check antenna and feedline for breaks or shorts.  If okay, you 
should hear a clearly-audible increase in background noise when the antenna is 
connected. 
 
!  
Spurious signals received:  Look for interference from nearby computers, modems, 
TVs, cordless phones, or other devices that may emit 28-MHz signals. 
 
!  
Distorted Receiver Audio:  Check for foreign debris in the speaker basket. 
 
! 
Erratic transmit:  Check antenna VSWR.  Also, check battery or power supply 
voltage.  If supply drops below 12-V under load, the radios regulator will drop out and 
operation will become erratic.  If you operate exclusively from 12-V batteries, reduce V-
REG output to 10.0V (measured on tab of U9) for added regulator headroom. 
 
!  High meter deflection on transmit, low RF output:  ALC pot R11 may be set too 
high (or VSWR may be high).  Adjust R11 for mid-scale deflection into a 50-Ohm load. 
 
!  Splatter, low meter deflection:  ALC pot R11 may be set too low (or there may be a 
feedline short).  Adjust for mid-scale deflection when transmitting into a 50-Ohm load. 
 
!  S-meter does not return to zero:  Confirm that V-REG (R78) is set for 10.5V on tab 
of U9.  Confirm that AGC threshold (R11) is set for 4.3V at RSSI test point (no signal).  
When both readings are set, adjust R17 for zero meter deflection. 
 
!  Poor carrier suppression:  Turn Mic gain off (fully CCW) and key the radio while 
monitoring signal on an external receiver.  Adjust R57 for minimum carrier. 
 
!  Low or distorted transmit audio:  Check to see if mic gain is set too low.  Also, 
make sure you are using a 600-Ohm low-Z dynamic microphone. 
 
!  Excessive background noise on signal, hum:  Mic gain set too high for the ambient 
noise conditions.  Also, is Mic or radio next to a power transformer or electric motor? 
 
TECHNICAL ASSISTANCE
 
 
If you have any problem with this unit first check the appropriate section of this manual.  
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. 
  
						

							MFJ-9410 Instruction Manual  10-Meter SSB Transceiver 
10 
You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial Park Road, 
Starkville, MS 39759; by Facsimile (FAX) to 601-323-6551; or by email to 
[email protected].  Send a complete description of your problem, an 
explanation of exactly how you are using your unit, and a complete description of your 
station. 
MFJ-9410 SCHEMATIC DIAGRAM