MFJ-993BRT 300 Watt IntelliTuner
TM
Automatic Remote Antenna Tuner Instruction Manual
© 2011 MFJ Enterprises, Inc
MFJ-993BRT Version 1A
1
The Basics
Introduction
The MFJ-993BRT 300 Watt IntelliTuner
TM
is a comprehensive remote automatic antenna tuning unit.
The MFJ-993BRT lets you rapidly tune almost any unbalanced or single-wire antenna automatically.
Balanced feedlines may be used with an MFJ-912 1.5 kW 4:1 balun connected to the MFJ-993BRT
antenna output.
MFJ's exclusive
InstantRecall
TM
,
IntelliTune
TM
and
AdaptiveSearch
TM
algorithms give you fast automatic
tuning with more than 2,500 non-volatile
VirtualAntenna
TM
memories. The memories permit virtually
instantaneous tuning when a previously tuned frequency is sensed by the MFJ-993BRT.
The tuner includes a highly efficient switched-L network with wide matching capability, 1.8 to 30 MHz
coverage, and heavy-duty high current/high-voltage relays. The MFJ-993BRT is rated at 300 watts PEP
SSB 150 watts CW and will match impedances from 6 to 1600 ohms (SWR up to 32:1).
A maximum of 256 values of inductance and 256 values of input capacitance. This provides a total of
131,072 L/C tuning combinations. The nominal tuning ranges are 0 to 24
µ
H and 0 to 3900 pF. And once
a match is found, the matching network values can be displayed so you may design your own fixed
matching network if desired.
Like all MFJ IntelliTuners
TM
, the MFJ-993BRT 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) and antenna, these tuner settings
are instantly restored and you’re ready to operate in milliseconds.
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 needed 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
TM
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 five watts. 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.
