MFJ MFJ-991B User manual

INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
MFJ ENTERPRISES, INC.
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]
COPYRIGHT 2005-2012 MFJ ENTERPRISES, INC.
C
Model MFJ-991B
VERSION 2B

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: [phone]; FAX: [phone]. Business hours:
M-F 8-4:30 CST.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
i
Contents
THE BASICS
Introduction...................................................................................................................................... 1
Features............................................................................................................................................ 2
Specifications................................................................................................................................... 2
Fast Start .......................................................................................................................................... 3
Front Panel....................................................................................................................................... 4
SWR/Wattmeter.................................................................................................................. 4
C-UP and C-DN Buttons .................................................................................................... 4
L-UP and L-DN Buttons..................................................................................................... 5
AUTO Button ..................................................................................................................... 5
TUNE Button...................................................................................................................... 5
StickyTuneTM .......................................................................................................... 5
POWER Button................................................................................................................... 5
Back Panel ....................................................................................................................................... 7
Power .................................................................................................................................. 7
Remote Port ........................................................................................................................ 7
Radio Interface.................................................................................................................... 7
Transmitter........................................................................................................................ 10
Ground .............................................................................................................................. 10
Wire .................................................................................................................................. 10
Antenna............................................................................................................................. 10
Installation ..................................................................................................................................... 10
SWR/Wattmeter............................................................................................................................. 11
SETUP
Power Level ................................................................................................................................... 12
Target SWR ................................................................................................................................... 12
Auto Tune SWR............................................................................................................................. 12
Antenna Memory ........................................................................................................................... 12
Meter Range................................................................................................................................... 13
OPERATION
Manual Tuning............................................................................................................................... 14
Component Limit........................................................................................................................... 14
Tuner Status Indicators .................................................................................................................. 15
Transceiver Foldback..................................................................................................................... 16
Grounding Hints ............................................................................................................................ 16
Antenna System Hints.................................................................................................................... 17
Coaxial Cable Selection.................................................................................................... 17
Location ............................................................................................................................ 17
Matching Problems ........................................................................................................... 18

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
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APPENDICES
Firmware Version Number ............................................................................................................ 19
Resetting the Tuner........................................................................................................................ 19
Factory Defaults................................................................................................................ 20
Delete Antenna Memory................................................................................................... 20
Total Reset ........................................................................................................................ 20
Self Test ......................................................................................................................................... 21
Power Down Circuit Test............................................................................................................... 22
Relay Test ...................................................................................................................................... 22
Wattmeter Calibration.................................................................................................................... 23
Frequency Counter Calibration...................................................................................................... 23
SWR Bridge Calibration ................................................................................................................ 24
Alinco Radio Interface................................................................................................................... 25
Connections ...................................................................................................................... 25
Operation .......................................................................................................................... 25
Icom Radio Interface...................................................................................................................... 26
Connections ...................................................................................................................... 26
Operation .......................................................................................................................... 26
Kenwood Radio Interface .............................................................................................................. 27
Connections ...................................................................................................................... 27
Operation .......................................................................................................................... 27
Yaesu Radio Interface/MFJ-5124Y ............................................................................................... 28
Connections for FT-100.................................................................................................... 28
Operation for FT-100........................................................................................................ 28
Connections for FT-450.................................................................................................... 29
Operation for FT-450........................................................................................................ 29
Connections for FT-857 or FT-897................................................................................... 30
Operation for FT-857 or FT-897....................................................................................... 30
Connections for FT-950.................................................................................................... 31
Operation for FT-950........................................................................................................ 31
Yaesu Radio Interface/MFJ-5124Y2 ............................................................................................. 32
Connections for FT-847.................................................................................................... 32
Operation for FT-847........................................................................................................ 32
Yaesu Radio Interface/MFJ-5124Y3 ............................................................................................. 33
Connections for FT-1000MP series of radios................................................................... 33
Operation for FT-1000MP series of radios....................................................................... 33
Connections for FTDX-9000 series of radios..................................................................... 34
Operation for FTDX-9000 series of radios......................................................................... 34
Yaesu Radio Interface/MFJ-5124Y4 ............................................................................................. 35
Connections for FT-2000 series of radios......................................................................... 35
Operation for FT-2000 series of radios............................................................................. 35
Connections for FTDX-5000 series of radios..................................................................... 36
Operation for FTDX-5000 series of radios......................................................................... 36
In Case of Difficulty ...................................................................................................................... 37
Technical Assistance...................................................................................................................... 37
List of Accessories......................................................................................................................... 37
Circuit Block Diagram................................................................................................................... 38

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
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FIGURES
Figure 1. Typical Installation Block Diagram ................................................................................ 4
Figure 2. MFJ-991B Front Panel .................................................................................................... 4
Figure 3. Button Action .................................................................................................................. 6
Figure 4. MFJ-991B Back Panel..................................................................................................... 7
Figure 5. Alinco Interface Cable..................................................................................................... 8
Figure 6. Icom Interface Cable ....................................................................................................... 8
Figure 7. Yaesu Interface Cable (FT-1000MP/-9000 series).......................................................... 9
Figure 8. Yaesu Interface Cable (FT-2000/-5000 series)................................................................ 9
Figure 9. SWR/Wattmeter ............................................................................................................ 11
Figure 10. Power-On Operations .................................................................................................. 19
Figure 11. MFJ-991B Circuit Block Diagram .............................................................................. 38
TABLES
Table 1. Antenna Memory Resolution.......................................................................................... 13
Table 2. Meter Needle Stationary Codes ...................................................................................... 15
Table 3. Meter Needle Bounce Codes .......................................................................................... 16
Table 4. Failure Messages............................................................................................................. 21

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
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MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
1
The Basics
Introduction
The MFJ-991B IntelliTunerTM lets you rapidly tune unbalanced, single-wire, or balanced (with external
balun) antennas automatically.
MFJ's exclusive InstantRecallTM, IntelliTuneTM and AdaptiveSearchTM algorithms give you fast automatic
tuning with more than 10,000 non-volatile VirtualAntennaTM memories. There are four banks of memory,
and each memory bank has over 2500 non-volatile memories for tuner settings.
The MFJ-991B IntelliTunerTM includes a highly efficient switching L-network with wide matching
capability, 1.8 to 30 MHz coverage, cross-needle power meters, an accessory remote control port, a radio
interface port, and heavy-duty 16 amp/1000 volt relays. It is rated at 300 watts to match 6 to 1600 ohms
antennas (SWR up to 32:1) or 150 watts to match a wider range of 6 to 3200 ohms (SWR up to 64:1).
A maximum of 256 values of capacitance and 256 values of inductance are available. With the
inductance switched between the input and output side, this provides a total of 131,072 L/C tuning
combinations. The nominal tuning ranges are 0 to 3900 pF and 0 to 24 μH.
The MFJ-991B IntelliTunerTM learns and remembers. When you transmit, it automatically adjusts for
minimum SWR and remembers the frequency and tuner settings, safely stored in non-volatile memory.
The next time you operate on that frequency (or close to it), the tuner settings are instantly restored and
you’re ready to operate in milliseconds. There are four banks of memory, which can learn and remember
more than 2500 frequencies and tuner settings per bank.
When you key your transmitter, MFJ’s InstantRecallTM checks its memory to see if you have operated on
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 technology) kicks in. It measures the
complex impedance of your antenna. Next, it calculates the components it needs and instantly snaps them
in. Finally, it fine-tunes to minimize SWR, and you’re ready to operate – typically in a fraction of a
second.
If the antenna impedance is not within the tuner’s measurement range, MFJ’s AdaptiveSearchTM
algorithm goes into action. Frequency is measured and relevant component values are determined. Only
those values are searched for fast tuning. If it still cannot find a match, the search is performed again
using a different search pattern.
The target tuned SWR can be set to 1.5 or 2.0. The minimum power to tune is approximately two watts,
with maximum SWR tuning accuracy occurring at tuning power levels of 10-20 watts. Manual tuning is
also available for “touching up” the tuning if desired.
Like all MFJ’s IntelliTunersTM, the MFJ-991B supports radio tuner interfaces that are compatible with
Alinco EDX-2 tuner, Icom AH-3 and AH-4 tuners, Kenwood AT-300 tuner, Yaesu FC-30 tuner, certain
Yaesu radios with a CAT system, and Yaesu FH-1 and FH-2 remote controls. Optional interface cables
MFJ-5124A (for Alinco), MFJ-5124I (for Icom), MFJ-5124K (for Kenwood), and MFJ-5124Y/Y2/Y3/Y4
(for Yaesu) are available from MFJ Enterprises, Inc. The optional MFJ-991RC Remote Control provides
most tuner controls, allowing convenient remote locating of the tuner itself.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
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The MFJ-991B tuner enters a “sleep” mode when idle and when no transmit signal is present, turning off
the microprocessor clock to avoid the generation of spurious signals.
Features
•Automatically matches antennas with impedances of 6 to 1600 ohms or 6 to 3200 ohms
•Handles 300 watts (match 6 to 1600 ohms) or 150 watts (match 6 to 3200 ohms)
•Tunes in less than 15 seconds, usually less than 5 seconds
•Over 10,000 non-volatile memories for tuner settings
•Four memory banks with over 2500 memories per bank
•Highly efficient switching L-network matching circuit
•1.8 to 30 MHz continuous frequency coverage
•Selectable target SWR 1.5 or 2.0 (default is 1.5)
•Selectable SWR threshold 0.5, 1.0 or 1.5 (default is 0.5 above target SWR)
•Lighted cross-needle SWR/wattmeter with high, low and auto range options
•Built-in frequency counter for remembering frequency-specific matching values
•SO-239 coax fed antenna connector
•Connector for random wire or single wire antennas
•Optional remote control
•Optional radio interface cables for compatible radios
Specifications
•Impedance matching range : 6 to 1600 ohms (300 watts) or 6 to 3200 ohms (150 watts)
•SWR matching range : Up to 8:1 for < 50 ohms and up to 32:1 for >50 ohms (300 watts)
Up to 8:1 for < 50 ohms and up to 64:1 for >50 ohms (150 watts)
•Minimum power for tuning : 2 watts (optimum SWR tuning accuracy occurs at 10-20 watts)
•Maximum power while tuning : 100 watts with foldback, 20 watts without foldback
•RF power limit : 300 watts SSB/CW
•Frequency range : 1.8 to 30 MHz continuous coverage
•Frequency counter accuracy : ±1 kHz across HF bands
•Capacitance range : 0 to 3900 pF (256 values)
•Inductance range : 0 to 24 μH (256 values)
•Relay rating : 16 amp 1000 volts
•Relay electrical life : 100,000 operations
•Relay mechanical life : 10 million operations
•Memory endurance : 1 million write cycles
•Memory data retention : > 200 years
•Power supply requirements : 12 - 15 volts DC
•Current consumption : 850 mA or less
•Dimensions (connectors not incl.) : 10.1 × 2.8 × 9.2 in; 257 × 71 × 234 mm (w × h × d)
•Weight : Approx. 3.7 lb; 1.68 kg
† Specifications and design are subject to change without notice.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
3
Fast Start
WARNINGS
●Never operate the tuner with its cover removed. Contact with the components inside the
tuner while transmitting will result in painful RF burns.
●Locate the tuner so that the rear terminals are not accessible during operation. The single
wire connection may have high voltage while transmitting.
●Disconnect all antennas from the tuner during lightning storms.
●Always tune with low power (2 watts minimum, 10-20 watts recommended), and with any
in-line amplifier bypassed. Apply maximum power only after tuning up.
●Never exceed tuner specifications.
1. Connect the tuner to a 12-15 VDC voltage source capable of supplying at least 850 milli-amps.
2. Connect your transmitter or amplifier output to the TRANSMITTER connector using a 50-ohm
coaxial cable.
3. Connect your coax-fed antenna to the ANTENNA connector using a 50-ohm coaxial cable, or
connect your random wire to the WIRE binding post.
4. Connect your ground connection to the GROUND post.
5. Press the [POWER] button to turn on the tuner.
6. Lock the [AUTO] button in to select semi-automatic mode.
Note: The AUTO button should always be IN (semi-automatic) unless a compatible radio
interface cable is connected between the MFJ-991B and your transceiver. This ensures
that the MFJ-991B does not attempt tuning during high-power operation, and is
particularly important when an HF amplifier is in-line.
Note: If an amplifier is in-line, it should always be bypassed prior to tuning.
7. Key your transmitter to output a carrier of 2-20 watts CW, FM or AM.
Note: Due to detector non-linearities at low power levels, best SWR tuning accuracy occurs at
10-20 watts.
8. Press and hold the [TUNE] button for one second to start the automatic tuning process. When
completed, check to ensure an SWR of 1.5 or less has been achieved before increasing RF power.
Note: If you have a tuning solution on one band or antenna and you then change bands or
antenna and attempt to transmit a tuning signal, the previous tuning solution may be
sufficiently severe such that no power is detected by the MFJ-991B (the MFJ-991B will
tell you to increase power). When this occurs, simply bypass the MFJ-991B and then
initiate a tune.
Note: If the tuner was unable to achieve the target SWR, the Reflected Power needle will
bounce three times when tuning completes.
9. You are ready to transmit with full power.
Note: During the automatic tuning process, the tuner will make some noise. These are the
relays switching at a very high rate and this is normal. Do not be alarmed.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
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Note: When the tuner power is OFF, the tuner is bypassed and RF from the transmitter or
amplifier goes directly to the antenna with no matching. The MFJ-991B always powers
up in bypass mode to ensure maximum receiver sensitivity if you are listening on a
different frequency than where tuning last occurred. When tuning starts, the MFJ-991B
reverts to previously stored matching values or finds a new match if no previous
information is in memory. You may bypass the tuner at anytime when the tuner power is
ON by pressing [C-DN] and [L-DN] simultaneously or pressing [TUNE] quickly. When
the MFJ-991B is bypassed, the reflected meter needle bounces to the 20-watt mark while
the switches are pressed.
Transmitter Automatic
Tuner
50-ohm Coax
Antenna
RF Ground 12 VD
C
Figure 1. Typical Installation Block Diagram.
Front Panel
MODEL
MFJ-991B
C-UP L-UP AUTO POWER
C-DN L-DN TUNE
AUTOMATIC ANTENNA TUNER
Dual Power Level
300/150 Watts
MFJ IntelliTuner
TM
0
10
30
50
100
200
300
0
5
20
40
60
8
5.0
3.0 2.0
1.5
1.2
Hi x1
Lo x.1
400-3083
1
10
Z
BYPASS
Figure 2. MFJ-991B Front Panel.
•SWR/Wattmeter: The cross-needle meter measures forward power, reflected power, and SWR. It
operates whenever the MFJ-991B is powered on. Full-scale readings are 300 watts forward and 60
watts reflected. The meter can be set to a low power range of 30 watts forward and 6 watts reflected,
or AUTO metering where the meter range is determined by the transmit power. The SWR is
measured at the point where the two needles cross. See “SWR/Wattmeter” on page 11 for more
detailed information.
•C-UP and C-DN Buttons: Used to manually increase or decrease the capacitance of the L-network
matching circuit. The capacitance range is 0 to 3900 pF. The upper limit of capacitance, dependent
on frequency, is restricted to limit the maximum voltage and current across the tuner’s components.