MFJ-993B IntelliTuner Automatic Antenna Tuner Instruction Manual
2005-2012 MFJ Enterprises, Inc.
4
Note: If the tuner was unable to achieve the target SWR, the Reflected Power needle will
bounce three times when tuning completes.
9. You are ready to transmit with full power.
Note: During the automatic tuning process, the tuner will make some noise. These are the
relays switching at a very high rate and this is normal. Do not be alarmed.
Note: When the tuner power is OFF, the tuner is bypassed and RF from the transmitter or
amplifier goes directly to the antenna with no matching. The MFJ-993B always powers
up in bypass mode to ensure maximum receiver sensitivity if you are listening on a
different frequency than where tuning last occurred. When tuning starts, the MFJ-993B
reverts to previously stored matching values or finds a new match if no previous
information is in memory. You may bypass the tuner at anytime when the tuner power is
ON by pressing [C-DN] and [L-DN] simultaneously or pressing [TUNE] quickly. When
the MFJ-993B is bypassed, the reflected meter needle bounces to the 20-watt mark while
the switches are pressed.
Transmitter MFJ-993B
50-ohm Coax
Antenna 1
RF Ground 12 VD
ntenna 2
Figure 1. Typical Installation Block Diagram.
Front Panel
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Lo
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400-3083
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MODEL
MFJ-993B
ANT
C-UP L-UP AUTO POWER
MODE C-DN L-DN TUNE
LCD VOL
AUTOMATIC ANTENNA TUNER
MFJ IntelliTuner
TM
Dual Power Level
300/150 Watts
Z
BYPASS
SWR
14.100MHz 1.1
FWD=100 REF=0.5
11.2 1.52 3SWR
0255075100PWR 300
Figure 2. MFJ-993B Front Panel.
• SWR/Wattmeter: The cross-needle meter measures forward power, reflected power, and SWR. It
operates whenever the MFJ-993B is powered on. The default full-scale readings are 300 watts
forward and 60 watts reflected power. The meter can be set to a low power range of 30 watts forward
and 6 watts reflected, or AUTO metering where the meter range is determined by the transmit power.
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