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MFJ MFJ-925, Instruction Manual

The MFJ MFJ-925 is a high-performance antenna tuner that guarantees superior signal quality. Don't miss out on optimizing your radio's performance - download the free Instruction Manual for the MFJ MFJ-925 from our website today. Unlock the full potential of your device and experience unmatched efficiency.

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MFJ-925 Super-Compact IntelliTuner Automatic Antenna Tuner 

Instruction Manual 

©

 2006 MFJ Enterprises, Inc. 

 

i

 

Contents 

 

THE BASICS 

Introduction...................................................................................................................................... 1 
Features............................................................................................................................................ 2 
Specifications................................................................................................................................... 2 
Fast Start .......................................................................................................................................... 3 
Front Panel....................................................................................................................................... 4 

SWR LED ........................................................................................................................... 4 
TUNE LED ......................................................................................................................... 4 
TUNE Button...................................................................................................................... 4 

Automatic/Semi-Automatic Tuning Mode ............................................................ 4 

ALT Button......................................................................................................................... 5 
POWER Button................................................................................................................... 5 

Back Panel ....................................................................................................................................... 6 

Power .................................................................................................................................. 6 
Radio Interface.................................................................................................................... 6 
Transmitter.......................................................................................................................... 9 
Antenna............................................................................................................................... 9 
Ground ................................................................................................................................ 9 

Installation ..................................................................................................................................... 10 

 
 

MISCELLANEOUS 

Antenna Memory ........................................................................................................................... 11 

IntelliTune

TM

 Algorithm ................................................................................................................ 11 

LC Limits....................................................................................................................................... 11 
Morse Code and Beeps .................................................................................................................. 12 
Foldback Circuit ............................................................................................................................ 12 
Grounding Hints ............................................................................................................................ 13 
Antenna System Hints.................................................................................................................... 13 

Location ............................................................................................................................ 13 
Matching Problems ........................................................................................................... 13 

 
 

APPENDICES 

Resetting the Tuner........................................................................................................................ 15 

Factory Defaults................................................................................................................ 15 
Delete Entire Antenna Memory ........................................................................................ 16 
Delete Antenna Memory Bank ......................................................................................... 16 
Total Reset ........................................................................................................................ 16 

Self Test ......................................................................................................................................... 17 
Power-Down Circuit Test .............................................................................................................. 18 
Relay Test ...................................................................................................................................... 18 
Frequency Counter Calibration...................................................................................................... 19 

Summary of Contents for MFJ-925

Page 1: ...ns Before Operating Equipment MFJ ENTERPRISES INC 300 Industrial Park Road Starkville MS 39759 USA Tel 662 323 5869 Fax 662 323 6551 COPYRIGHT 2006 MFJ ENTERPRISES INC C Model MFJ 925 VERSION 0A Super Compact IntelliTuner Automatic Antenna Tuner TM ...

Page 2: ......

Page 3: ... Back Panel 6 Power 6 Radio Interface 6 Transmitter 9 Antenna 9 Ground 9 Installation 10 MISCELLANEOUS Antenna Memory 11 IntelliTuneTM Algorithm 11 LC Limits 11 Morse Code and Beeps 12 Foldback Circuit 12 Grounding Hints 13 Antenna System Hints 13 Location 13 Matching Problems 13 APPENDICES Resetting the Tuner 15 Factory Defaults 15 Delete Entire Antenna Memory 16 Delete Antenna Memory Bank 16 Tot...

Page 4: ...nt Panel 4 Figure 3 Button Action 5 Figure 4 MFJ 925 Back Panel 6 Figure 5 Radio Interface Connector 6 Figure 6 Alinco Interface Cable 7 Figure 7 Icom Interface Cable 7 Figure 8 Kenwood Interface Cable 8 Figure 9 Yaesu Interface Cable FT 100 FT 817 FT 857 FT 897 8 Figure 10 Yaesu Interface Cable FT 847 9 Figure 11 Power On Operations 15 Figure 12 MFJ 925 Circuit Block Diagram 22 TABLES Table 1 Jum...

Page 5: ... ready to operate in milliseconds The antenna has four banks of memory which can learn and remember more than 2500 frequencies and tuner settings When you key your transmitter MFJ s InstantRecallTM checks its memory to see if you have operated that frequency before If so tuning is instantaneous and you re ready to operate If not MFJ s IntelliTuneTM algorithm based on MFJ s famous SWR Analyzer tech...

Page 6: ...e 6 to 1600 ohms SWR matching range up to 8 1 for 50 ohms and up to 32 1 for 50 ohms Minimum power for tuning 2 watts Maximum power while tuning 100 watts with foldback 20 watts without foldback RF power limit 200 watts SSB CW Frequency range 1 8 to 30 MHz continuous coverage Frequency counter accuracy 1 kHz across HF bands Capacitance range 0 to 3961 pF nominal 256 values Inductance range 0 to 24...

Page 7: ...l cable or connect your random wire to the ANTENNA connector through the supplied adaptor 4 Connect your ground connection to the GROUND post 5 Press the POWER button to turn on the MFJ 925 tuner 6 Press the ALT button momentarily until there is one beep One beep indicates that memory 1 is selected 7 Key your transmitter to output a carrier of 10 watts CW FM or AM 8 Press and hold the TUNE button ...

Page 8: ...es SWR of 1 5 or less two beeps indicate SWR of 1 6 to 2 0 three beeps indicate SWR of 2 1 to 2 5 and four beeps indicate SWR of 2 6 to 3 0 For SWR above 3 0 SWR di di dit di dah dah di dah dit will be sent on CW StickyTune allows for one handed tuning operation Normal tuning requires keying the transmitter with one hand and using the other hand to push the TUNE button to start the tuning process ...

Page 9: ...nna and bank if available is instantly restored from memory when enabled POWER Button Used to turn the power on and off When the power is off the tuner is placed in bypass mode When turning on the power the tuner automatically restores all previous settings and displays the target SWR on the main screen WARNING Do not turn the power on and off rapidly otherwise the tuning setting memory can be cor...

Page 10: ...uner interface connector If separate power supplies are used to power the MFJ 925 the MFJ 925 should be powered on first both LEDs blink once and then turn on the radio so the radio knows an external tuner is attached The radio will disable its internal tuner if it has one and use the external tuner The Radio Interface works with radios that are compatible with Alinco EDX 2 Icom AH 3 and AH 4 Kenw...

Page 11: ...Table 1 Jumper JP2 Setting The MFJ 5114A interface cable provides power and control between an Alinco radio and the MFJ automatic tuner Supported Alinco radios are DX 70 DX 77 and any Alinco radio that supports the Alinco EDX 2 tuner Pin 1 Ground connects to pins 4 and 5 of Radio Interface Plug Pin 2 13 8V connects to pins 2 and 3 of Radio Interface Plug Pin 3 Key connects to pin 6 of Radio Interf...

Page 12: ...nd 3 of Radio Interface Plug 4 1 3 2 4 6 5 Kenwood Rear Panel View 1 2 3 4 5 6 Figure 8 Kenwood Interface Cable The MFJ 5114Y interface provides power and control between a Yaesu radio and the MFJ automatic tuner Supported Yaesu radios are FT 100 FT 817 FT 857 FT 897 and any Yaesu radio with compatible CAT system Push the TUNE button on the tuner for 0 5 to 2 seconds to start the tuning process Im...

Page 13: ... Radio Interface Plug Pin 4 is not connected Pin Ground connects to pins 4 and of Radio Interface Plug Pin 6 is not connected Pin 7 is not connected Pin 8 is not connected Pin 9 is not connected 2 g 3 RX 5 5 Yaesu Rear Panel View 1 1 2 3 4 5 6 7 8 9 1 1 2 3 4 5 6 7 8 9 Figure 10 Yaesu Interface Cable FT 847 Transmitter SO 239 connector for coax cable from transmitter or transceiver There is a bias...

Page 14: ...the feed through insulators may have high RF voltages These voltages can cause serious RF burns if the terminals are touched when transmitting Be sure to locate the tuner so these terminals cannot accidentally be contacted during operation 2 Install the tuner between the transmitter and the antenna Use a 50 ohm coaxial cable such as RG 58 to connect the transmitter or amplifier to the connector ma...

Page 15: ...n for non amateur frequency bands between 160 and 10 meters is approximately 0 2 percent of the lower frequency of each band There are two primary memory banks each with four secondary memory banks Each secondary memory bank has 2500 memory locations Tuner settings are stored in memory separately in primary memory 1 and primary memory 2 This provides memory for up to eight different antennas See A...

Page 16: ...By One Beep Indicates By Two Beeps By Pressing Primary Memory 1 2 ALT 1 second Memory Bank Bank A 1 beep Bank B 2 beeps Bank C 3 beeps Bank D 4 beeps Off 5 beeps ALT 1 second Bypass Toggle Bypass Mode L 0 and C 0 Restore Last L C Setting TUNE 0 5 sec Tuned SWR SWR 1 5 1 beep SWR 2 0 2 beeps SWR 2 5 3 beeps SWR 3 0 4 beeps SWR 3 0 SWR TUNE for 0 5 to 2 seconds StickyTune On Off TUNE 2 seconds Tunin...

Page 17: ...equate for RF grounding because they are single conductors Ground rods by themselves are almost useless for dependable RF grounding RF grounds work much better when spread out over a large area especially when they employ multiple connections directly to the equipment ground point Metal water pipes heating ducts and fences may work especially if they are connected together with multiple wires but ...

Page 18: ...duce the difficulty in matching an antenna with a tuner Never center feed a half wave multi band antenna with a high impedance feedline that is close to an odd multiple of a quarter wave long Never center feed a full wave antenna with a feedline close to a multiple of a half wave long If this tuner will not tune a multi band antenna add or subtract 1 8 wave of feedline for the band that won t tune...

Page 19: ...to calibrate the SWR bridge POWER ALT TUNE Press and hold to delete current antenna memory POWER ALT TUNE For the operations not pressing or pressing it more than seven times will cancel the operation after idling four seconds beep two times and then resume normal operation POWER ALT TUNE Figure 11 Power On Operations Resetting the Tuner Each time the tuner is powered off the microprocessor saves ...

Page 20: ...ory bank first select the primary memory 1 or 2 and the memory bank A B C or D that you want to delete See ALT Button on page 5 for details 1 Turn off the power to the tuner 2 Press and hold only the ALT button while turning the power on Both LEDs will blink until the button is released 3 Within four seconds of releasing ALT press the TUNE button two times 4 After releasing TUNE for four seconds t...

Page 21: ...is also the test of the LEDs 5 Release the TUNE button The unit then checks for short circuits power down detection level and wakeup circuitry 6 Press ALT button and the green LED should blink once 7 Press TUNE button and the green LED should blink once 8 The unit then tests its non volatile memory Notice this step will reset the unit to its factory default settings 9 If the unit is okay a repetit...

Page 22: ...ssage PASS will be sent as Morse code di dah dah dit di dah di di dit di di dit and the green LED will blink If there is a problem message PD FAIL will be sent as Morse code repetitively and the red LED will blink 9 Turn the power off Relay Test WARNING Turn off the transmitter power or disconnect the transmitter before performing this test otherwise damage to the tuner can result To test the rela...

Page 23: ...egrated circuit on the front side of the front panel circuit board until both LEDs are lighted up The green LED lights when the calibration is below 29 MHz the red LED lights when the calibration is above 29 MHz and both LEDs light up when the calibration equals to 29 MHz 9 Unkey the transmitter Turn off the power to the transmitter and the tuner 10 Secure the cover back onto the tuner SWR Bridge ...

Page 24: ...tter s power 16 Key the transmitter to output 100 watts and adjust the REF trimpot VR2 located next to the RADIO INTERFACE connector until the forward meter yes the forward meter shows 100 watts the reflected meter is at full scale 17 Press the TUNE button to end calibration 18 Turn off the power to the transmitter and the tuner 19 Remove the cross needle wattmeter from header HD1 20 Remove the tr...

Page 25: ... mfjenterprises com Send a complete description of your problem an explanation of exactly how you are using your unit and a complete description of your station Also include the firmware version number of your unit List of Accessories MFJ 1316 12 VDC 1 5 amp power supply MFJ 4116 BiasTee DC power injector MFJ 5114A Interface cable for compatible Alinco radios MFJ 5114I Interface cable for compatib...

Page 26: ...prises Inc 22 Figure 12 MFJ 925 Circuit Block Diagram Transmitter Radio Interface Impedance Sensor SWR Sensor Frequency Counter Memory Microcontroller Relay Drivers Ground Antenna Inductors 0 24 uH Capacitors 0 3900 pF Push Buttons LEDs Buzzer User Interface Z Bias Tee RF Voltage Regulator DC ...

Page 27: ...ervice Department at 662 323 0549 or the MFJ Factory at 662 323 5869 4 This warranty does not apply to kits sold by or manufactured by MFJ Enterprises Inc 5 Wired and tested PC board products are covered by this warranty provided only the wired and tested PC board product is returned Wired and tested PC boards installed in the owner s cabinet or connected to switches jacks or cables etc sent to MF...

Page 28: ...MFJ 925 Manual Version 0A Printed In U S A 12 2006 300 Industrial Park Road Starkville MS 39759 MFJ ENTERPRISES INC ...

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