MFJ IntelliTuner -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 200 MFJ ENTERPRISES, INC.5
C
Model MFJ-991B
VERSION 1A
IntelliTuner
Automatic Antenna Tuner
TM

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2004-2005 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..................................................................................................... 4
AUTO Button .....................................................................................................................4
TUNE Button...................................................................................................................... 4
POWER Button................................................................................................................... 5
Back Panel ....................................................................................................................................... 6
Power .................................................................................................................................. 6
Remote Port ........................................................................................................................ 6
Radio Interface.................................................................................................................... 6
Transmitter.......................................................................................................................... 7
Ground ................................................................................................................................ 7
Wire .................................................................................................................................... 8
Antenna............................................................................................................................... 8
Installation ....................................................................................................................................... 8
SWR/Wattmeter............................................................................................................................... 9
SETUP
Power Level ..................................................................................................................................... 9
Target SWR ................................................................................................................................... 10
Auto Tune SWR............................................................................................................................. 10
Antenna Memory ........................................................................................................................... 10
Meter Range................................................................................................................................... 11
OPERATION
Manual Tuning............................................................................................................................... 11
Component Limit........................................................................................................................... 12
Foldback Circuit ............................................................................................................................ 12
Tuner Status Indicators .................................................................................................................. 12
Grounding Hints ............................................................................................................................ 14
Antenna System Hints.................................................................................................................... 14
Location ............................................................................................................................ 14
Matching Problems ........................................................................................................... 14

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2004-2005 MFJ Enterprises, Inc.
ii
APPENDICES
Firmware Version Number ............................................................................................................ 16
Resetting the Tuner........................................................................................................................ 16
Factory Defaults................................................................................................................ 16
Delete Antenna Memory................................................................................................... 17
Total Reset ........................................................................................................................ 17
Self Test ......................................................................................................................................... 17
Power Down Circuit Test............................................................................................................... 18
Relay Test ...................................................................................................................................... 19
Wattmeter Calibration.................................................................................................................... 19
SWR Bridge Calibration ................................................................................................................ 20
Frequency Counter Calibration...................................................................................................... 21
In Case of Difficulty ...................................................................................................................... 21
Technical Assistance...................................................................................................................... 22
List of Accessories......................................................................................................................... 22
Circuit Block Diagram................................................................................................................... 22
FIGURES
Figure 1. Installation Block Diagram.............................................................................................. 3
Figure 2. MFJ-991B Front Panel .................................................................................................... 4
Figure 3. Button Action .................................................................................................................. 5
Figure 4. MFJ-991B Back Panel..................................................................................................... 6
Figure 5. Alinco Interface Cable..................................................................................................... 7
Figure 6. Icom Interface Cable ....................................................................................................... 7
Figure 7. SWR/Wattmeter .............................................................................................................. 9
Figure 8. Power-On Operations .................................................................................................... 16
Figure 9. MFJ-991B Circuit Block Diagram ................................................................................ 22
TABLES
Table 1. Antenna Memory Resolution.......................................................................................... 10
Table 2. Meter Needle Stationary Codes ...................................................................................... 13
Table 3. Meter Needle Bounce Codes .......................................................................................... 13
Table 4. Failure Messages............................................................................................................. 18

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2004-2005 MFJ Enterprises, Inc.
1
The Basics
Introduction
The MFJ-991B IntelliTunerTM let you rapidly tune antennas automatically: unbalanced or single-wire (or
balanced, with an external balun).
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 tuner includes a highly efficient switching L-network with wide matching capability, 1.8 to 30 MHz
coverage, cross-needle power meters, a port for an accessory remote control, 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.
All MFJ IntelliTunersTM learn and remember. When you transmit, they automatically adjust for minimum
SWR and remember the frequency and tuner settings, safely stored in non-volatile memory. The next
time you operate on that frequency (or close to it), these 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
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 – all 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 SWR can be set at 1.5 or 2.0. The minimum power to tune is approximately five watts. You
can manually tune where you can’t transmit (for listening out of ham bands).
All MFJ’s IntelliTunersTM support 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, and certain Yaesu radios with
CAT system. Optional interface cables MFJ-5124A (for Alinco), MFJ-5124I (for Icom), MFJ-5124K (for
Kenwood), MFJ-5124Y and MFJ-5124Y2 (for Yaesu) are available from MFJ Enterprises, Inc. The
optional MFJ-993RC Remote Control provides most tuner controls, allowing convenient remote locating
of the tuner itself.
The tuners enter a “sleep” mode when idle and when no transmit signal is present, turning off the
microprocessor clock to avoid the generation of spurious signals.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2004-2005 MFJ Enterprises, Inc.
2
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)
• Tune 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
• Selectable SWR threshold 0.5, 1.0 or 1.5
• Lighted cross-needle SWR/wattmeter with high, low and auto range options
• Built-in frequency counter
• SO-239 coax fed antenna connector
• Connector for random wire or single wire antennas
• Optional remote control
• Optional radio interface 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
• 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
• Frequency counter range: up to 50 MHz
• 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 requirements: 12 - 15 volts DC, 2.1 × 5.5 mm coaxial plug, center pin positive
• Current consumption: 850 milli-amp or less
• Dimensions (approx.): 10.1 × 2.8 × 9.2 in. (257 × 71 × 234 mm) (width/height/depth)
not including connectors
• 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
©2004-2005 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 (about 10 watts). Apply maximum power only after tuning up.
●Never exceed tuner specifications.
●Do not transmit with a high SWR for extended periods of time.
1. Connect the tuner to a 12-15 VDC voltage source capable of supplying at least 850 milli-amp.
2. Connect your transmitter 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. Lock the [AUTO] button in to select semi-automatic
mode.
6. Key your transmitter to output a carrier of 10 watts CW, FM or AM.
7. Press and hold the [TUNE] button for one second to start the automatic tuning process. When
completed, check to ensure an SWR of 2.0 or less before increasing RF power.
8. You are ready to transmit.
Note: During the automatic tuning process, the tuner will make some noise. These are the relays
switching at a very fast pace and it is normal operation. Do not be alarmed.
Note: When the tuner power is OFF, the tuner is in bypass mode and RF from the transmitter goes
directly to the antenna with no matching. When the tuner power is ON, pressing [C-DN] and
[L-DN] simultaneously or pressing [TUNE] quickly places the tuner in bypass mode (zero
inductance and zero capacitance) and indicates by the reflected needle bouncing to 20-watt
mark.
Transmitter Automatic
Tuner
50-ohm Coax
Antenna
RF Ground 12 VD
C
Figure 1. Installation Block Diagram.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2004-2005 MFJ Enterprises, Inc.
4
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 tuner is power on. Full-scale readings are 300 watts forward and 60 watts
reflected. The meter can be set to low power range of 30 watts forward and 6 watts reflected. The
SWR is measured at the point where the two needles cross. See “SWR/Wattmeter” on page 8 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.
Note: Pressing [C-UP] and [C-DN] simultaneously toggles the capacitor between the input
and output sides of the L-network. Forward needle bounces to 30-watt mark when the
capacitor is on the transmitter side. Reflected needle bounces to 5-watt mark when the
capacitor is on the antenna side.
• L-UP and L-DN Buttons: Used to manually increase or decrease the inductance of the L-network
matching circuit. The inductance range is 0 to 24 μH. The upper limit of inductance, dependent on
frequency, is restricted to limit the maximum voltage and current across the tuner’s components.
Note: Pressing [C-DN] and [L-DN] (both DOWN buttons) simultaneously places the tuner in
bypass mode. The reflected needle bouncing to the 20-watt mark indicates this. RF from
the transmitter goes directly to the antenna with no matching.
• AUTO Button: Used to select automatic or semi-automatic tuning mode. Button out selects
automatic mode – the tuning routine is automatically started when at least five watts of power is
applied and the SWR is a preset amount above the preset target SWR. Button in selects the semi-
automatic mode – the tuning routine starts only when the [TUNE] button is pressed.
Note: During the tuning process, the tuner will make some noise. These are the relays
switching at a very fast pace and it is normal operation. Do not be alarmed.
• TUNE Button: Has three different functions based on the length of time you press and hold it before
releasing. Press [TUNE] quickly (less than 0.5 second) to bypass the tuner. RF from the transmitter
goes directly to the antenna with no matching.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2004-2005 MFJ Enterprises, Inc.
5
Press and hold [TUNE] for 0.5 to 2 seconds to start the automatic tuning process. The transmitter
must be keyed first with at least five watts of power. When the SWR is already below the target
SWR, pressing [TUNE] will fine-tune the match for a lower SWR, if possible.
“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. To
toggle the StickyTune mode on and off, press and hold the [TUNE] button for two seconds. The
Reflected Power needle goes to 60-watt mark when on and to 5-watt mark when off. When
StickyTune is enabled, the tuning process starts automatically when the transmitter is keyed with at
least five watts of power regardless of the SWR. This works in both automatic and semi-automatic
modes.
• POWER Button: Used to turn the power on and off. Note that during power-on the analog meter
bounces once to indicate the model 991. When the power is off, the tuner is placed in bypass mode
(straight through from TRANSMITTER to ANTENNA and WIRE). When power is turned on, the
tuner automatically restores all previous settings.
WARNING: Do not turn the power on and off rapidly, otherwise the tuning setting
memory can be corrupted and the unit will have to be reset to factory defaults.
BUTTON ACTION
TUNE C-UP
L-UPTUNE
TUNE L-DN
TUNE C-DN
C-DN L-DN
C-UP C-DN
Press + to switch the capacitor between the input and output side.
Press + to bypass the antenna tuner.
Press + to cycle theAuto Tune SWR among 0.5, 1.0 and 1.5 above the target SWR.
Press + to toggle the Target SWR between 1.5 and 2.0.
Press + to cycle the Memory among banks A, B, C and D.
Press + to cycle the Meter Range among 30 watts, 300 watts and auto range.
Press + to increase both capacitance and inductance.
C-UP L-UP
AUTO
C-UP
L-UP
C-DN
L-DN
TUNE
POWER
Press in to select semi-automatic mode, out to select automatic mode.
Press to decrease inductance.
Press to increase inductance.
Press to decrease capacitance.
Press to increase capacitance.
Press in to turn power on, out to turn power off.
Press less than 0.5 second to bypass the tuner; press and hold for 0.5 to 2 seconds to start the
tuning process; press and hold for more than two seconds to toggle the StickyTune on and off.
Press + to overwrite tuner memory with the current tuner setting.+
TUNE L-DNC-DN
Press + to+ toggle the power level between 300 and 150 watts.
TUNE C-UP L-UP
Figure 3. Button Action.

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2004-2005 MFJ Enterprises, Inc.
6
Back Panel
RADIO
INTERFACE
+
POWER
12VDC
850mA
REMOTE
PORT
ANTENNA
TRANSMITTER
GROUND
MFJ ENTERPRISES, INC.
STARKVILLE, MS USA
!
Do not connect WIRE and
ANTENNA at same time!
WIRE
Figure 4. MFJ-991B Back Panel.
• Power: This jack accepts a standard 2.1 × 5.5 mm coaxial plug with positive center and negative
sleeve. The tuner requires 12 volts DC at up to 850 milli-amp. The use of a regulated supply is not
mandatory but is recommended for best performance. An optional 12 volts DC 1.5 amp power
supply, the MFJ-1316, is available from MFJ Enterprises, Inc.
WARNING: Do not apply voltages greater than 18 volts to this unit, or permanent damage
to the unit may result.
Note: When the tuner power is OFF, the tuner is in bypass mode and RF from the transmitter
goes directly to the antenna with no matching.
• Remote Port: A female DB-9 connector for connecting to the MFJ-993RC Remote Control,
allowing remote operation of the tuner. The MFJ-993RC duplicates all the front panel buttons except
[POWER]. In addition, there are two LEDs on the remote control. The red Tuning LED lights to
indicate tuning is in progress and the green SWR LED lights when the SWR is below the target SWR.
Note: To use the remote control, the [AUTO] button on the automatic tuner must be locked in;
otherwise, Automatic mode is selected.
• Radio Interface: A 3.5 mm stereo phone jack for connecting to the tuner interface connector of
compatible radios. Most radios provide +13.8 VDC power thought its tuner interface connector. If
separate power supplies are used to power the MFJ-991B, the MFJ-991B should be powered on first
(both needles will bounce) 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, Kenwood AT-300, Yaesu FC-30, and certain Yaesu radios with CAT system. When connected to
a compatible radio, simply press the [TUNER] or [AT] button on the radio; for certain Yaesu, press
the [TUNE] button on the tuner to start the automatic tuning process. The radio will automatically
switch to CW mode (AM for Yaesu), transmit a 10-watt carrier, and start the tuning process. Once
the automatic tuning is completed, the radio will return to its previous mode and power setting.
WARNING: Make sure the +13.8 volts connection on the radio’s tuner port is capable of
supplying at least 850 mA of current, since the MFJ-991B use up to 850 mA.