MFJ MFJ-616 User Manual

MFJ-616 Speech Intelligibility EnhancerTM Instruction Manual

INTRODUCTION

The MFJ-616

Speech Intelligibility Enhancer

is a powerful communication tool that surrounds your operating position with crystal-clear electronically-enhanced audio. It also puts the fun back into ham radio! Here are some of the high-tech features we think you'll enjoy:

Studio Quality:

The

Speech Intelligibility Enhancer

is designed to drive two identical high quality speakers installed three or more feet apart. This configuration improves intelligibility, enhances frequency response, and dramatically increases spatial presence. Once your system is set up, you'll think you're in a broadcast studio!

Speech Intelligibility EnhancerTM:

everyone's hearing response changes over time. Our exclusive

Every radio has different audio characteristics--and

Speech Intelligibility Enhancer

tailors the sound of your radio especially for your ears. Young or old, you'll hear more clearly than ever before!

Dual Amplifiers:

Two powerful monolithic IC amplifiers deliver deep, rich, undistorted audio

to high quality, hi-fidelity speakers (not supplied).

Adjustable Balance:

A front-panel

Balance

control aligns speakers for dead-center positioning

regardless of speaker placement or differences in ear sensitivity.

Easy-to-Operate:

Large knobs, easy-to-access switches, and a wide-open panel layout make the

MFJ-616 very easy to set up and use.

Dual Input:

Switch between radios with the push of a button--no messing with patch cables

behind the desk.

By-Pass Function:

Switch

Speech Intelligibility Enhancer

in or out without cutting off the

speakers. This feature is especially helpful for sound comparisons during the frequency set-up.

Multiple Outputs:

Choose individual 3.5mm monaural jacks or a stereo jack wired for computer-style speakers. Also, a front panel switch turns off your speakers, the stereo headset stays active. Front panel phone jack is attenuated to headset levels (deactivated with internal jumpers).

Multiple Power Sources:

Use transceiver's 13.8-volt supply, wall adapter, dedicated supply, or

12-volt battery to power your unit.

Rugged Construction:

Attractive all-metal cabinet, conservative component selection, and space-age SMD circuitry ensure solid performance for years to come. Fully covered by MFJ's "No Matter What" one year limited warranty.

Before attempting to operate your MFJ-616, please read this manual thoroughly. It contains important details you'll need to know to obtain the best performance from your unit.

MFJ-616 Speech Intelligibility EnhancerTM Instruction Manual

JACKS AND CONTROLS

Front View:

Volume Balance 300 Hz 600 Hz 1200 Hz 2400 Hz

1. Volume:

2. Balance:

3. 300 Hz:

4. 600 Hz:

5. 1200 Hz:

6. 2400 Hz:

7. Bypass:

Adjusts overall loudness of both channels.

Establishes central balance between right and left speakers. Cuts or emphasizes lowest speech frequencies. Cuts or emphasizes mid-range speech frequencies.

Cuts or emphasizes upper-range speech frequencies. Cuts or emphasizes syllabant sounds and adjacent channel "chatter".

Turns

listening.

8. Input A/B:

9. Speaker:

10. Phones:

Selects between two sources.

Disables speakers--used when monitoring with headphones.

Accepts 1/4" stereo headphone plug, normally attenuated for phones (attenuation

deactivated internally).

11. Power:

Selects between unamplified and amplified signals.

Rear View:

23456

MFJ-616 Speech Intelligibility Enhancer

A B

Bypass Input A/B Speaker Phones Power

Speech Intelligibility Enhancer

A B

10 11

function on and off for comparative

+12VDC

123456

1. Power:

Accepts 2.1-mm power plug to supply 12-15 Vdc to the unit.

2. Right Speaker:

3. Left Speaker:

Accepts 3.5-mm mono phone plug for left-hand monitor speaker.

4. Stereo Speaker:

5. Input A:

6. Input B:

Accepts RCA plug from first radio (auxiliary audio or speaker line).

Accept RCA plug from second radio (auxiliary audio or speaker line).

MFJ ENTERPRISES, INC

STARKVILLE, MS USA

Right

Speaker

Left

Speaker

Stereo

Speaker

Input

Accepts 3.5mm mono phone plug for right-hand monitor speaker.

Accepts 3.5-mm stereo plug for computer-style speaker pairs.

MFJ-616 Speech Intelligibility EnhancerTM Instruction Manual

SET-UP INSTRUCTIONS

Power Sources:

Power your unit from any stable 12-15 Vdc source capable of delivering 1.5 Amps--including 13.8-volt high-current transceiver supplies, smaller dedicated power sources, properly rated wall adapters, and 12-volt batteries. The MFJ-616 features supplemental internal filtering, but hum and noise may still occur if your source is under-rated or very poorly regulated. Protect both power leads with 2-Amp fuses when using a high-current source such as a station supply. The controller's external power jack accepts a 5.5-mm x 2.1-mm coaxial plug. You may obtain extra plugs from RadioShack (274-1567 or equivalent). Wire (+) voltage to center terminal, and (-) to common, as shown:

2-A

Power Supply

Important Note: Unregulated DC sources (simple wall cubes, solar panels, etc.) may dam age your unit. Never apply more than 15 volts.

Headphones:

Use stereo headphones rated at 8-40 Ohms impedance. The front-panel headphone jack accepts a standard 1/4" stereo plug. If stereo phones are unavailable, you may use monaural phones with a mono plug if JMP4 and J MP5 are removed (factory default). JMP4 and JMP5 are located on the main PC board directly behind the headphone jack.

Speakers:

For best results, use a matched pair of high quality speakers housed in properlydesigned cabinets. Acoustic suspension or ported drivers in the 4-to-6 inch range work especially well for speech. Any voice-coil impedance between 4 and 16 ohms is acceptable. Tweeters should be disconnected in extended-range monitors to reduce high-frequency noise contribution. Use monaural or stereo patching, as shown below:

Stereo Plug

+--

Mono Plugs

When preparing speaker cables, it's important to

maintain proper lead phasing

. If speakers

are cross-phased, frequency response and efficiency suffer due to acoustic cancellation.

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