MFJ MFJ-9402X, MFJ-9402 User Manual

MFJ-9402 Instruction Manual 2 Meter SSB Transceiver

INTRODUCTION

Congratulations on your choice of the MFJ-9402. We think you'll enjoy countless hours rag-chewing, chasing grids, contesting, and roving as you explore the fascinating world of VHF weak-signal communication. Please read this manual thoroughly before attempting to operate your unit. Here are some of the radio's features we think you'll like:

Easy to Operate: Just turn on and tune in! No microprocessor mumbo-jumbo to learn, and no complex commands to memorize.

Potent Signal: Constant Current syllabic speech processing gives your signal 4-6 dB added punch to break pileups or climb above the noise.

Energy Efficient: All-analog circuitry uses minimal energy. Mountain top and rove on portable power, or operate from home with a small 2-Amp regulated supply.

Sensitive Receiver: A low-noise front-end and doubly-balanced mixer fight intermod, yet dig into band noise for weak signals. If the signal's there, you'll hear it!

Excellent Selectivity: Sharper selectivity does make a difference on VHF. Fight contest QRM and enjoy reduced passband noise with HF-style 2.3 kHz ladder filter.

Real S-Meter: Full-sized electromechanical meter displays subtle changes. Aim your beam with pin-point accuracy and give out signal reports that mean something!

Agile Tuning: Reduction-drive analog VFO lets you scan for signals quickly, then zero in smoothly without sudden rate shifts or stair-stepping. Ideal for fast-paced hunt-andpounce operation during contests and band openings!

Amplifier Friendly: Built-in FET switch keys solid-state or tube amps. Output signal is tailored for most popular multi-mode "brick" amplifiers (call 800-647-1800 for the latest information on Mirage VHF-amplifier products).

Built to Last: Conservative design, premium FR-4 plate-through PC board, state-of-theart SMD layout, handsome brushed-aluminum panel, and tough vinyl-clad case make for good looks and years of dependable service.

Optional MFJ-416 CW Module: Communicate with CW stations instantly--no need to switch modes, sidebands, or to fiddle with the RIT. Just grab the key and start sending. A must for snagging elusive grids, extra contest points, or auroral contacts!

At home or on the road, you'll enjoy superb two-meter performance with your MFJ-9402. Best of all, it's fully backed by MFJ's exclusive NO MATTER WHAT one-year guarantee. If it breaks, we'll take care of it.

MFJ-9402 Instruction Manual 2 Meter SSB Transceiver

GENERAL DESCRIPTION

The MFJ-9402 is a compact and economical SSB transceiver designed especially for fixed or portable communication in the weak-signal segment of the two-meter band. Although normally configured for USB voice communication, the MFJ-9402 will also operate on CW with the addition of the MFJ-416 semi-QSK CW-adapter module. Energy-efficient analog circuitry conserves energy, while syllabic RF speech processing ensures on-air performance equal to larger and more powerful radios. Other features include a sharp HF-style crystal filter, built-in heavy-duty 3" speaker, analog mechanical S-meter, "ergonomic" operating controls, and a built-in phone jack for walkman style stereo phones.

Typical Specifications

Receiver Section:

Frequency Coverage:.................................. 144.000-144.300 MHz

Receiver Type: ........................................... Single-conversion superhet

Frequency Control:..................................... Crystal-heterodyne VFO, low-side injection

IF Frequency:.............................................. 10 MHz

IF Selectivity: .............................................-6 dB @ 2.3 KHz

AGC: ..........................................................Audio-derived, 70-dB range

Sensitivity:..................................................MDS <.1 uV, S9 = 10 uV

AF Output:..................................................500 mW speaker, 100 mW phones

Average Rx Current: .................................. 60-mA, (S-meter lamp disabled)

Transmitter Section:

RF Power Output:.......................................7 watts PEP into 50 ohms*

VSWR Tolerance: ......................................3:1 or greater

Peak Tx Current: ........................................1.5 Amps (13.8 vdc)

Speech Enhancement: ................................ RF compression, syllabic rate

Spurious Attenuation:................................. -60 dBc or better

CW Generation:..........................................A1 carrier, adjustable offset**

Mic Input:................................................... 600-Ohm dynamic, PTT

* Note that most "10-watt input" multi-mode solid-state amplifiers are spec'd for FM service and require

significantly less than 10-watts for linear SSB operaton.

** The MFJ-416 CW adapter is required for CW operation ($39.95). Easy-to-install plug-in board

provides semi-QSK operation and built-in sidetone.

MFJ-9402 Instruction Manual 2 Meter SSB Transceiver

QUICK-START OPERATING INSTRUCTIONS

Power Supply: Use any well-regulated 13.8-V DC supply (1.5-amp or greater) or a

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suitably-rated 14-V battery pack. The MFJ-9402 will also run on 12-volts at slightly reduced RF output. Use a 5.5mm x 2.1 mm coaxial power plug with the + lead attached to the center pin of the connector (use Radio Shack 274-1569).

Microphone: The MFJ-290 handheld microphone was especially selected for MFJ-

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9400-series radios, but virtually any 600-ohm dynamic mic will work if it has a 5-pin DIN connector wired as shown below (use RadioShack 274-003).

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

Important Note

Never use an amplified microphone--it will overdrive the speech processor.

The PTT switch must cut both mic line and PTT line during receive.

Mic

PTT

Gnd

Antenna: Use any horizontally polarized 2-meter antenna exhibiting a VSWR of 2:1

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or less at 144.2 MHz. Avoid antennas with unknown or high VSWR. A simple dipole or omni-directional halo may be adequate for local contacts, but a 5-10 element directional yagi will yield vastly superior long-range performance and is strongly recommended (see antenna tips on page 5).

Speech Processor: The MFJ-9402 features a built-in syllabic speech processor. For

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best results, hold the mic about 1-inch from your lips and speak normally. Avoid close-talking or yelling. The S-meter should deflect about 1/2-scale with normal

speech. A Mic Gain trimpot is located on the rear panel. The factory-default gain setting is mid-range, or 12-o'clock.

External Power Amplifiers: The MFJ-9402 is especially designed to compliment

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most popular 10-watt input 2-meter FM/SSB amplifiers. The Ext Amp jack provides ground-closure on transmit to key the amplifier. Be sure to follow all amplifier manufacturer's instructions closely and make any needed adjustments to avoid exceeding your amplifier's safe drive level on SSB. In many cases, SSB drive requirements will be significantly lower than those required for FM operation. See amplifier primer and drive-level adjustment instructions on page 4.

Receiver Preamplifiers: If your external PA features a built-in GaAsFET preamp, try

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using it. If you observe an audible improvement in signal-to-noise ratio on weak signals and a desierable increase in overall sensitivity, you may wish to leave it in line. However, if it makes the background noise dis-proportionately louder than weak

MFJ-9402 Instruction Manual 2 Meter SSB Transceiver

signals, leave it off. Also, note that extra preamplification may degrade the radio's overload performance and IMD immunity when strong signals are near-by.

CONNECTING A MULTI-MODE AMP TO THE MFJ-9402

Pwr

Antenna

Coax

Ext Keying

Pwr

MFJ-9402

Mic Amp

Ext

Radio

Two-wire Patch Cable

Antenna

Drive Requirements: The "10-watt input" rating assigned VHF amps typically refers to

FM operation. As illustrated below, SSB drive requirements may be substantially less because of the need to maintain amplifier linearity. Overdriving on SSB results in two types of interference-generating non-linearity. First, gain compression causes amplifier IMD performance to deteriorate rapidly, adding distortion to the audio and making your signal needlessly broad. Second, saturation causes flat-topping, a condition that clips the SSB waveform and produces sever splatter. On SSB, your amplifier should always be driven at levels below the point where significant gain compression begins.

Saturation

SSB

FM/CW

Operating

Region

RF INPUT (watts)

Gain

Excessive

Drive

912

OUTPUT

(watts)

150

Gain

Compression

Operating

Region

100

Input/Output Power Curve for a "Typical" 150-W VHF Amplifier

Setting Drive Level: As a rule-of-thumb, plan to run your VHF amp at .66 x full-rated

FM output power. For example, if your brick is rated for 150 watts on FM, run it at 100 watts PEP on SSB (.66 x 150 = 99). In most cases, this will keep your amp linear. The MFJ-9402 is normally adjusted for 7-watts PEP output. While this is right for some amps, it may overdrive others. If so, you may reduce drive by re-setting ALC trimpot R73 for the desired level (R73 is located near the antenna connection on the left-rear corner of the PC board--see Page-9 for trimpot locations). To monitor amplifier output, connect a true peak-reading wattmeter between the amp and a low-VSWR 50-ohm load (a good antenna will do). To generate a ALC-limited SSB signal, speak loudly into the microphone so the processing meter deflects vigorously. Adjust R73 until your amplifier delivers 66% of its full-rated FM output on the wattmeter. If you use an average-reading wattmeter (Bird 43, etc), note that the meter movement will read a lot lower--only about 40-50% of the PEP value with syllabic processing (or 40-50 Watts for a 150-W amp). Also, note that the transceiver's processor meter will read higher as you increase ALC

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