MFJ MFJ 9475 User Guide

MFJ-9475 Instruction Manual 75-Meter SSB Travel Radio

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! Let's begin with an introduction to some special features we think you'll like!

•••• Easy to Operate: A "back-to-basics" radio, the MFJ-9475 is simple to use. There are

no complex microprocessor functions to master, and you'll be on the air in minutes!

•••• Great Receiver Performance: Your radio features a quiet DBM (doubly-balanced

mixer) front-end and carefully-distributed gain. If the signal is there, you'll hear it. If the signal

isn't

there, you won't hear a lot of other things that shouldn't be there!

•••• Analog S-Meter: Responsive mechanical meter gives accurate meaningful reports.

•••• Excellent Selectivity: Sharp ladder filter cuts adjacent chatter and focuses transmitter

power where you need it most.

•••• Smooth, Stable VFO: Effortless tuning with custom-manufactured 8:1 reduction-

drive ball-bearing VFO tuning capacitor.

•••• Powerful AF Output: Big audio--even on the road--from a special Philips BTL audio

chip and rugged 3" speaker.

•••• Full-time RF Speech Processing: Commanding speech cuts through QRM.

Compare it with your 100-Watt rig--you'll be

amazed

by the signal reports.

•••• Travel Light: Packs a heavy punch without the heavy power supply! Designed to run

on NiCad's or the ultra-light MFJ-4110 AC wall-adapter supply.

•••• Rugged PA: Bullet-proof final runs cool, tolerates accidental shorts and opens.

•••• Made to Last: Conservative design, premium plate-through pc board, quality

components, handsome brushed-aluminum panel, and a tough vinyl-clad case ensure years of dependable service.

You'll enjoy countless hours operating the MFJ-9475. If anything goes wrong, it's fully backed by MFJ's exclusive "No Mat ter What" 1-year guarantee. If it breaks, we'll take care of it!

Note: Due to bandwidth considerations, no CW adapter is offered for the MFJ-9475.

MFJ-9475 Instruction Manual 75-Meter SSB Travel Radio

MFJ-9475 Control Locations and Functions

Antenna

Mic Gain

Power

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.

3.9

3.95

4.0 3.75

3.85

3.8

Volume

Off

Power Tune

Mic

Xmit

Off

MFJ 75-Meter SSB Radio

Model MFJ-9475

Pwr

Front Panel

1. Meter: Shows signal strength on RX, ALC Voltage on TX.

2. Power Switch: Turns on power to the transceiver.

3. Mic Connector: 5-pin DIN connector for 600Ω dynamic microphone.

4. Tune Switch: Injects carrier for antenna tuner or other adjustments.

5. "Xmit" LED: Illuminates when unit is transmitting.

6. Tuning Dial: VFO control for tuning in stations.

7. Volume Control: Adjusts speaker volume to a comfortable listening level.

8. "Pwr" LED: Illuminates when power is turned on.

MFJ-9475 Instruction Manual 75-Meter SSB Travel Radio

Assembling Your Station

You'll 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. Walladapter 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 274-1567) with (+) connected to the center pin.

Microphone: The MFJ-9475 speech processor was designed around our companion MFJ-290 600Ω Dynamic Microphone. However, you may use any low-Z dynamic microphone with a switched cartridge and PTT line by installing a 5-pin DIN connector (Radio Shack 274-003 or equivalent), as shown below:

Pin 3: PTT Line Pin 4: Mic Line Pin 1,2,5: Ground

Mic (#4) PTT (#3)

Gnd (#1,2,5)

Antenna: The MFJ-9475 works with any 75-Meter 50Ω antenna exhibiting low VSWR (2:1 or less is considered acceptable for amateur radio service).

unknown or high VSWR.

See page 5 for more detailed 75-meter antenna suggestions.

Avoid antennas with

Setting up Your Station

The MFJ-9475 is small in size, allowing you to set up an amateur radio station in nearly any location. The better the operating environment, the better your radio will perform. Find a space that is sheltered, dry, and dust free. Avoid surfaces that are exposed to direct sunlight, strong magnetic fields, rapid temperature changes, or high ambient noise levels. Connect your transceiver to a good earth ground, if available.

Antenna

Power Supply

(MFJ-4110 Shown)

--or any

2A @ 13.8V

Regulated

Source

(50-Ohm)

Power Plug

5.5 mm OD

2.1 mm ID

MFJ-290 or Equivelent

Mic

600-Ohm Dynamic

MFJ-9475 Instruction Manual 75-Meter SSB Travel Radio

Operating Your MFJ-9475

3.9 3.85

Off

Power Tune

Mic

Off

3.95

4.0

Xmit

MFJ 75-Meter SSB Radio

Model MFJ-9475

3.8

3.75

Volume

Pwr

Receiving: The MFJ-9475 is extremely simple to operate. To get started, press the

POWER

switch on (the green

for a comfortable listening level. Now, tune in your station with the

PWR

LED should illuminate). Adjust the

VOLUME

VFO TUNING

control

knob.

That's all there is to it!

Antenna Tuners: If you are using a tuner, adjust controls for the strongest received signal first--before keying the transmitter. This will bring antenna VSWR into the "ballpark". For final adjustment, press the radio's generate a steady carrier (the red

XMIT

LED should light). Be sure to follow the tuner

TUNE

switch to

ON.

This will

manufacturer's procedures when adjusting for minimum VSWR.

Before You Transmit: Your radio's VFO dial was calibrated at the factory. However, under FCC rules, you are solely responsible for the operating frequency of your transmitter (MFJ is not). If you have doubts concerning the dial's accuracy, check it out against a radio with a digital frequency readout before operating near the band edges. Also, know where the sub-band margins are for your particular class of license.

Transmitting: Press the PTT switch and speak normally while holding the microphone 1-2 inches away (the red

XMIT

LED should light). The radio's S-meter should deflect about 1/2 scale as you speak. Resist the temptation to yell or close-talk. The speech processor is designed to automatically re-adjust gain for each syllable. Over-driving the radio's speech amplifier circuitry will detract from its performance. As you speak, note that the S-meter is indicating ALC voltage--not RF output power. Speaking loudly to push the meter higher will have no benefit.

Antenna VSWR: Always check VSWR before using a new or questionable antenna. Highly reactive loads will affect ALC meter readings during transmit, making them appear abnormally high or low, depending upon the nature of the mismatch. In extreme cases, highly-reactive loads can cause the transmitter to emit spurious out-of-band signals in violation of FCC rules. If you notice that your ALC voltage is swinging excessively high or low, consider this a "wake-up call" to check the condition of your antenna!

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