MFJ MFJ-654 User Manual

Model MFJ-654

VERSION 1A

INSTRUCTION MANUAL

CAUTION: Read All Instructions Before Operating Equipment

MFJ ENTERPRISES, INC.

300 Industrial Park Road

Starkville, MS 39759 USA

Tel: 662-323-5869 Fax: 662-323-6551

DISCLAIMER

Information in this manual is designed for user purposes only and is not intended to supersede information contained in customer regulations, technical manuals/documents, positional handbooks, or other official publications. The copy of this manual provided to the customer will not be updated to reflect current data.

Customers using this manual should report errors or omissions, recommendations for improvements, or other comments to MFJ Enterprises, 300 Industrial Park Road, Starkville, MS 39759. Phone: (662) 323-5869; FAX: (662) 323-6551. Business hours: M-F 8-4:30 CST.

MFJ-654 hamProAudio

Microphone Equalizer/Conditioner Instruction & Technical Manual

TABLE OF CONTENTS

TOPIC PAGE

1. TABLE OF CONTENTS 2

2. LIST OF FIGURES 2

3. INTRODUCTION AND FEATURES 3

4. TYPICAL SPECIFICATIONS 4

5. SYSTEM CONTROLS 5 a. FRONT PANEL JACKS AND CONTROLS 5 b. REAR PANEL JACKS AND CONTROLS 7

6. SYSTEM SETUP 8 a. INTERNAL HEADERS 8 b. INTERNAL JUMPER BLOCK 9 c. CABLES 17 d. POWER 17 e. HEADPHONES 17 f. RADIO AUDIO 17

7. THEORY OF OPERATION 18

8. MFJ-654 EASY-START INSTRUCTIONS 20

9. IN CASE OF DIFFICULTY 23

10.TECHNICAL ASSISTANCE 23

LIST OF FIGURES Figure 1 Front Panel Jacks and Controls 5

Figure 2 Rear Panel Jacks and Controls 7 Figure 3 Internal Headers 8 Figure 4-10 Internal Jumper Blocks 9-13 Figure 12 Yaesu Mic Jack Pinout, Front View 14 Figure 13 Functional Diagram 18 Figure 14 Compression and Gating Characteristics 19 Figure 15-16 Schematic 24-25

LIST OF TABLES Table 1 Sample Jumper Settings Table for Yaesu FT-1000 Series 14

Table 2 Microphone Pinout 16

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INTRODUCTION & FEATURES

INTRODUCTION

The MFJ-654 hamProAudio Microphone Equalizer/Conditioner was designed with the serious operator in mind. Based on the Broadcast Industry Standard Speech Compression IC the SSM-2166 from Analog Devices it allows the operator flexibility in the use of input sources and output methods.

The 8 band Equalizer was designed to use the most desired center frequencies and “Q” possible.

FEATURES Choice of 3 Input Sources: In order to add versatility MFJ has included the

following input sources for the MFJ-654:

1. A standard RJ-45 input jack common to most new radios.

2. Standard 8 pin round chassis connector for the majority of the radios

produced in the last 25 years.

3. MFJ’s own input consisting of a 3.5 -mm jack that allows the user to choose from feeding audio, audio and a PTT function for use with the Heil series of Boom-Mic Headsets, or even provides phantom voltage on the tip for the MFJ-393 Boom-Mic Headphones or on the ring for use with a computer Boom-Mic or Boom-Mic headset.

These features are included along with allowing you to feed audio from a computer, TNC or Modem.

Fully Adjustable Gain Amplifier: You have control of the output level to bring weak microphones up to a useful level or will provide over 1.2 volts peak to peak using the auxiliary output.

Wide Range Compression Settings: With an adjustable compression setting from 1:1 to 15:1 you control the amount of compression to get your signal thought the toughest of band conditions.

Adjustable Downward Expansion Level and Delay: No more feeding the background noise into your signal. The MFJ-654 allows you to set the level of Downward Expansion to only pass audio when you are talking and a delay to minimize the cutting in and out between words.

Selectable 8 Band Equalizer: You have full control of your audio with up to ±16dB of control for 8 center frequencies.

J-654 hamProAudio

Microphone Equalizer/Conditioner Instruction & Technical Manual

INTRODUCTION & FEATURES

Audio Pass Through from your Radio: No need to switch the headphones

from the MFJ-654 to the radio. At the push of a button you can instantly switch from normal operation to a test mode that allows you to adjust the settings without going on the air with the built in monitor amplifier.

By-pass Function: Switch the MFJ-654 in or out and you still have the radios audio in the headphones useful when you want to Rag Chew and don’t need the Compression or Downward Expansion of the MFJ-654.

Multiple Outputs: The MFJ-654 has multiple outputs for both receive/test audio and Microphone audio. No need to have to hunt for an adapter to switch between 3.5 -mm or 1/4inch stereo phone jacks. Microphone audio is fed out through the RJ-45 connector through the 3.5 mm Auxiliary Output or through a separate 3.5 mm jack that gives true balanced output if you need it.

Rugged Construction: Attractive all-metal cabinet, conservative component selection, space age SMD Circuitry and extensive RF filtering 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-654, please read the manual thoroughly. It contains important detail about setting up your unit to obtain the best performance.

TYPICAL SPECIFICATIONS

Input source……………………Dynamic or electret microphone low or high Z

Stereo or Monaural radio audio. Sound card or Modem

Output ………………………….High or low Z. Adjustable signal level Bandwidth …………………….20 kHz Total harmonic distortion ….1% maximum, <0.2% typical.

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J-654 hamProAudio

Microphone Equalizer/Conditioner Instruction & Technical Manual

SYSTEM CONTROLS

MFJ-654 JACKS AND CONTROLS

14 15 16 17 18 19 20 21 22

MFJ Microphone Equalizer/ConditionerhamProAudio™

0 0 0 0 0 0 0 0

MICROPHONE IN

COMPRESSION MONITORLEVEL DELAYOUTPUT

EQ INPUT LEVEL

400 Hz200 Hz100 Hz50 Hz

INPUT

OUTPUT LEVEL POWER

Max Min Max Min Max Min

DOWNWARD EXPANSION

MFJ-654

3200 Hz2400 Hz1600 Hz800 Hz

EQUALIZER

Max Min Max Min

Min

BYPASS POWER

Max

OFF

OFF/BYPASS

OFF

1 2 3 4 5 6 7 98 10 11 12

Figure 1: MFJ-654 Front Panel Jacks and Controls

Bottom Rows

1. 8 pin Microphone Input Jack: Accepts input from any standard 8 pin microphone.

2. RJ-45 Microphone Input Jack: Accepts the input from a standard RJ-45 Microphone.

3. Compression Level: Controls the Compression function from no Compression to 15:1 maximum Compression.

4. Equalizer Input Level LED: This LED allows you to set the input level to the Equalizer section.

5. Input Level Gain: This control sets the input level to the Equalizer section.

6. Output Gain Level LED: A one time adjustment will allow this LED to monitor your output level and allow you to set the gain level for any input source easily.

7. Output Level Gain: Allows a wide range of output levels for various radios or other uses.

8. Downward Expansion Level: Allows adjustment of the required audio level to allow the unit to pass audio. Great for noisy conditions.

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J-654 hamProAudio

Microphone Equalizer/Conditioner Instruction & Technical Manual

SYSTEM CONTROLS

9. Downward Expansion Delay: Sets the amount of time that the internal amplifier will remain open with no audio. Great to hold the audio open between syllables and words.

10. Power On LED: Instant visual identification if you are using the MFJ-654 or just the standard microphone.

11. Monitor Gain: Control the audio level in the headphones when in the test position.

12. Bypass ON/OFF Switch: Allows you to either use your Microphone direct (out) or through the MFJ-655 (in).

13. Power ON/OFF Switch: Cuts the power to the unit on (in) or off (out).

Top Rows

14. 50 Hz: Cuts or emphasizes lowest speech frequencies.

15. 100 Hz: Cuts or emphasizes lowest speech frequencies.

16. 200 Hz: Cuts or emphasizes lowest speech frequencies.

17. 400 Hz: Cuts or emphasizes mid-range speech frequencies.

18. 800 Hz: Cuts or emphasizes mid-range speech frequencies.

19. 1600 Hz: Cuts or emphasizes upper-range speech frequencies.

20. 2400 Hz: Cuts or emphasizes syllabant sounds and adjacent channel “chatter”.

21. 3200 Hz: Cuts or emphasizes syllabant sounds and adjacent channel “chatter”.

22. Equalizer ON & OFF/Bypass: Cuts the Equalizer on (in) or off (out).

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J-654 hamProAudio

Microphone Equalizer/Conditioner Instruction & Technical Manual

SYSTEM CONTROLS

MFJ ENTERPRISES, INC.

STARKVIL LE, MS USA

POWER

12VDC

HEADPHONE AUDIO

FROM RADIO

FROM MFJ-654

OUT

EXTERNAL

PTT

SWITCH

AUX.

AUDIO

OUTPUT

BALANCED

AUDIO

OUTPUT

LEVEL

LED

AUX. AUDIO INPUT

MICROPHONE

OUT

RECEIVED

AUDIO INPUT

1 2 3 4 5 6 7 9 8 10 11

Figure 2: MFJ-654 Rear Panel Jacks and Controls

1. Power: Accepts 2.1 –mm power plug to supply 12-15 Vdc to the unit.

2. From Radio/From MFJ-654: This switch allows the audio to be fed from the radio to the headphones or in the test mode for the audio from the microphone to be fed to the headphones for setting the MFJ-654. Additionally in the test mode the PTT is disabled allowing you to key the microphone without keying the radio.

3. Headphone Output: Allows you to use a pair of 3.5 –mm stereo headphones. The test audio is mono fed into both sides of the phones. The radio audio is what your radio puts out. Handy if you have a Main and a Sub-receiver.

4. Headphone Ouput: Same function as number 3 but for ¼ inch stereo headphones.

5. External PTT Input: This ¼ inch jack allows PTT from a Hand Switch or Foot Switch.

6. Auxiliary Output: This 3.5 –mm jack allows direct audio to be fed out from the unit. Useful when high levels of audio are required as up to 1.2 volts peak to peak are available.

7. Balanced Output: This 3.5 –mm stereo jack give a balanced output.

8. Output LED Level Set: This trim pot is used to adjust the point at which the LED illuminates.

9. Auxiliary Input: This multifunction input allows just about anything to be used with the MFJ-654 by setting the appropriate input jumpers.

10. RJ-45 Output: This is where the MFJ-5398 or the MFJ-5397MX is attached.

11. Received Audio Input: This jack allows either stereo or mono (if wired properly) audio from your radio is applied.

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J-654 hamProAudio

Microphone Equalizer/Conditioner Instruction & Technical Manual

INTERNAL HEADERS

SYSTEM SETUP

Figure 3: Internal Headers

1. Header 1: This sets the input of the unit to your specific microphone. Default 1-2 is set to 680 ohms the standard impedance setting for most stock microphones. If you need low impedance then move the jumper to positions 3-4. Remove for high impedance microphones.

2. Header 3: This allows the PTT line to be placed on the ring of the 3.5 –mm auxiliary input jack. Default is off.

3. Header 4: This header allows phantom voltage to be fed to electret microphones Default is 0 volts pins 1-2 shorted. Move this jumper to pins 3-4 for 1.5 volts, 5-6 for 5 volts or 7-8 for 8 volts.

4. Header 5: High impedance output. Default is shorted for low impedance output but if required remove this jumper for approximately 50K output impedance.

5. Header 6: This header allows the phantom voltage set by header 4 to be passed to the ring of the Auxiliary input jack. Default is off. If used with standard computer microphone/headphones set to 5 volts.

6. Header 7: This header ties the CT of the output transformer allowing a balance output to be available at the 3.5 –mm jack. Default is off.

7. Header 8: This header allows the PTT line to be placed on the Auxiliary Output ring terminal of the 3.5 –mm jack. Default is off.

8. Header 9: This Header places phantom voltage on the microphone input line and the tip of the 3.5 mm input jack. It must be shorted when using a microphone requiring phantom voltage.

9. Header 10: This header allows the transformer to be bypassed to increase the low frequency response. Default is 1-2 not bypassed.

10. Header 11: This header allows the transformer to be bypassed to increase the low frequency response. Default is 1-2 not bypassed.

11. Header 12: This header grounds the Mic Ground to the radio and must be shorted if the transformer is being bypassed. Default is off.

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