MFJ-993B IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2005 MFJ Enterprises, Inc.
1
The Basics
Introduction
The MFJ-993B IntelliTunerTM lets you rapidly tune any antenna automatically: balanced, unbalanced, or
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 InstantRecallTM, IntelliTuneTM and AdaptiveSearchTM algorithms give you fast automatic
tuning with more than 20,000 non-volatile VirtualAntennaTM memories. Each of the two antennas has
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 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) 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 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 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 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.
