Fast Start .......................................................................................................................................... 3
Front Panel....................................................................................................................................... 4
single-wire. The MFJ-993B is a comprehensive automatic antenna tuning center with SWR/wattmeter,
antenna switch for two antennas, and a 4:1 current balun for balanced lines.
MFJ's exclusive InstantRecall
tuning with more than 20,000 non-volatile VirtualAntenna
four banks of memory; 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, backlight LCD display, 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 wider range of 6 to 3200 ohms (SWR up to 64:1).
A maximum of 256 values of inductance and 256 values of capacitance are available. With the
capacitance 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 24 μH and 0 to 3900 pF.
All MFJ IntelliTuners
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) and antenna, these tuner settings are instantly restored
and you’re ready to operate in milliseconds. Each of two antenna selections has 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 InstantRecall
that frequency before. If so, tuning is instantaneous and you’re ready to operate. If not, MFJ’s
IntelliTune
TM
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 AdaptiveSearch
algorithm goes into action. Frequency is measured and relevant components 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 1.0 through 2.0. The minimum power to tune is approximately two watts.
You can manually tune where you can’t transmit (for listening out of ham bands).
All MFJ’s IntelliTuners
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.
TM
lets you rapidly tune any antenna automatically: balanced, unbalanced, or
TM
, IntelliTuneTM and AdaptiveSearch
TM
learn and remember. When you transmit, they automatically adjust for minimum
TM
support radio tuner interfaces that are compatible with Alinco EDX-2 tuner,
●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 and balanced line 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 MFJ-993B to a 12-15 VDC voltage source capable of supplying at least 1 amp.
2. Connect your transmitter to the TRANSMITTER connector using a 50-ohm coaxial cable.
3. Connect your coax-fed antenna to the ANTENNA 1 connector using a 50-ohm coaxial cable, or
connect your random wire to the WIRE binding post, or connect your balanced line antenna to the
BALANCED LINE binding posts and connect a jumper between the other two posts as indicated.
4. Connect your ground connection to the GROUND post.
5. Press the [POWER] button to turn on the MFJ-993B tuner. Place the [ANT] button in the out
position to select antenna 1. Press 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 on the MFJ-993B 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 (ANTENNA 1) 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 watts.
• 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 10 for
more detailed information.
• LCD Display: A 2-line by 16-character alphanumeric display. It displays the tuner’s various menus
and status. The display contrast can be adjusted by the [LCD] control on the front panel. Below the
display are the SWR and power bar meter scales. Refer to Figures 11 and 12 for descriptions of the
various displayed information.
• LCD Contrast Control: A trimpot control that adjusts the contrast of the LCD display. Use a small
flat blade screwdriver and turn clockwise to increase contrast.
• ANT Button: Used to select the antenna to tune. Button out selects Antenna 1; button in selects
Antenna 2. The Antenna indicator on the main display indicates the selected antenna. A balanced
feedline or a single-wire antenna is, by default, Antenna 1. Changing the [ANT] button will switch
the antenna only when there is no RF power; also, the tuner setting for the selected antenna, if
available, is instantly restored from memory when enabled.
• MODE Button: Time-sensitive and used to navigate through the various main menus and to enter or
exit the setup menus.
• 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 3908 pF (picofarads). The upper limit of capacitance,
dependent on frequency, is used to limit the maximum voltage and current across the tuner’s
components. This limit can be removed in the LC Limit setup menu, but is not recommended.
Note: Pressing [C-UP] and [C-DN] simultaneously toggles the capacitor between the input
0
0
3
0
0
2
2
0
0
0
1
1
0
0
5
2.0
3.0
0
1
.
5
1
Hi x1
.
2
Lo
0
x.1
1
14.100MHz 1.1
FWD=100 REF=0.5
11.2 1.52 3SWR
0255075100PWR300
MFJ IntelliTuner
AUTOMATIC ANTENNA TUNER
SWR
MODEC-DNL-DNTUNE
LCDVOL
TM
C-UPL-UPAUTOPOWER
ANT
Z
BYPASS
Dual Power Leve l
300/150 Watts
Figure 2. MFJ-993B Front Panel.
and output sides of the L-network. Forward needle bounces to 30 watts when the
capacitor is on the transmitter side. Reflected needle bounces to 5 watts 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 24.86 μH (microhenries). The upper limit of
inductance, dependent on frequency, is used to limit the maximum voltage and current across the
tuner’s components. This limit can be removed in the LC Limit setup menu, but is not recommended.
Shortcut: Press both [L-UP] and [L-DN] buttons simultaneously to toggle SWR Beep on and
off. See “SWR Beep Menu” on page 17.
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 2 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. The Auto/Semi indicator on
the main display indicates the selected mode.
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.
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 2 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. When
enabled, a bar appears on top of the Auto/Semi indicator, and the tuning process starts automatically
when the transmitter is keyed with at least 2 watts of power regardless of the SWR. This works in
both automatic and semi-automatic modes. One beep indicates on and two beeps indicate off.
• VOL Control: A trimpot control that adjusts the volume level of the audio SWR meter. Use a small
flat blade screwdriver and turn clockwise to increase volume level.
• POWER Button: Used to turn the power on and off. Note that during power-on the analog meter
bounces three times (to indicate the model number, 993). When the power is off, the tuner is placed
in bypass mode and Antenna 1 is selected. 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 corrupted and the unit will have to be reset to factory defaults.
Note: When the tuner power is OFF, the tuner is in bypass mode and RF from the transmitter
goes directly to the antenna (ANTENNA 1) with no matching.
Press in to turn power on, out to turn power off.
Press in to select antenna 2, out to select antenna 1.
Press to switch main modes and setup modes.
Press to increase capacitance.
Press to decrease capacitance.
Press to increase inductance.
Press to decrease inductance.
Press in to select semi-automatic mode,
out to select automatic mode.
POWER
ANT
MODE
C-UP
C-DN
L-UP
L-DN
AUTO
POWER LEVEL
TARGET SWR
AUTO TUNE SWR
METER RANGE
PEAK HOLD
MODE
MEMORY
IntelliTune
SWR BEEP
BEEP
REFRESH
MODE
+
MODE
C-UP
+
L-UP
LC LIMIT
Press or to turn on
or incr ease setting.
Press or to turn off
or decrease se tting.
-UPL-UP
-DNL-DN
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 switch the capacitor between the input and output side.
Press + to toggle the SWR Beep on and off.
Press + to increase both capacitance and inductance.
Press + to bypass the antenna tuner.
Press + to toggle the Target SWR between 1.5 and 2.0.
Press + to cycle the Auto Tune SWR among 0.5, 1.0 and 1.5 above the target SWR.
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 + toggle the power level between 300 and 150 watts.
Press + to overwrite tuner memory with the current tuner setting.+
TUNE
C-UPC-DN
L-DNL-UP
C-UPL-UP
C-DNL-DN
TUNEC-UP
L-UPTUNE
TUNEC-DN
TUNEL-DN
TUNEC-UPL-UP
TUNEL-DNC-DN
Figure 3. Mode Button Flow Chart and Button Action.