MFJ MFJ-991B - The Basics; Introduction

MFJ-991B IntelliTuner Automatic Antenna Tuner Instruction Manual
 2005-2012 MFJ Enterprises, Inc.
1
The Basics
Introduction
The MFJ-991B IntelliTuner
TM
lets you rapidly tune unbalanced, single-wire, or balanced (with external
balun) antennas automatically.
MFJ's exclusive InstantRecall
TM
, IntelliTune
TM
and AdaptiveSearch
TM
algorithms give you fast automatic
tuning with more than 10,000 non-volatile VirtualAntenna
TM
memories. There are four banks of memory,
and each memory bank has over 2500 non-volatile memories for tuner settings.
The MFJ-991B IntelliTuner
TM
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 IntelliTuner
TM
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 InstantRecall
TM
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
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 – typically in a fraction of a
second.
If the antenna impedance is not within the tuner’s measurement range, MFJ’s AdaptiveSearch
TM
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 IntelliTuners
TM
, 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.