MFJ-991 / MFJ-994 IntelliTuner Automatic Antenna Tuners
Instruction Manual
©
2004 MFJ Enterprises, Inc.
9
needle will read “300” for high range and “30” for low range until the buttons are released, to indicate the
range selected.
The meter can be set to auto range. Auto range automatically sets the meter scales according to the input
RF power to the tuner. Forward power greater than 30 watts or reflected power greater than six watts
automatically sets the meter to the high power range. Forward power less than 25 watts and reflected
power less than four watts automatically set the meter to the low power range. To toggle auto range on
and off, press the [TUNE] and [C-DN] buttons simultaneously. The reflected needle will read “60” for
auto range ON and “5” for auto range OFF.
The SWR is read from the eight red SWR curves that range from
1.0 to infinity. The SWR is measured by observing the point
where the forward and reflected power needles cross on the red
curved scales across the center of the meter. No cumbersome or
time-consuming SWR sensitivity adjustments are required with
this meter. Figure 7 shows an SWR of approximately 2.0.
The meter also indicates various operational states of the tuner. Refer to “Tuner Status Indicators” on
page 12 for more details.
Setup
You can set up how the MFJ-991/MFJ-994 tuner works and behaves. In addition to displaying power and
SWR, the meter also indicates tuner status when you make setup changes. The meter needles bounce, or
rise to one point and stay, to provide information. In this mode the meters do
not
indicate power levels.
For example, when you press [C-DN] and [L-DN] simultaneously to place the tuner in bypass mode, the
reflected needle bounces to the 20 watts mark until you release the buttons. Table 2 summarizes the
meter needle stationary and bounce codes.
Target SWR
You can set the target SWR to 1.5 or 2.0. The tuning process will stop when a match with an SWR less
than or equal to the target SWR is found. The default is 1.5. Setting the target SWR to 2.0 may require
shorter tuning times. You can toggle the target SWR between 1.5 and 2.0 by pressing [TUNE] and [C-
UP] simultaneously; the meter needles intersect at SWR of 1.5 or 2.0 to indicate the change.
Auto Tune SWR
You can set the SWR threshold
to 0.5, 1.0 or 1.5. In the automatic mode, the tuning process will
automatically start when the SWR is above the target SWR by this amount of SWR threshold. For
example, for target SWR of 1.5 and auto tune SWR of 1.0, the tuning process will start whenever the
SWR is above 2.5 (1.5 + 1.0) and there is at least 5 watts (10 watts for MFJ-994) of RF power. Default is
1.0. Press [TUNE] and [L-UP] simultaneously to cycle the auto tune SWR among 0.5, 1.0 and 1.5
(Reflected Power meter needle reads 5, 20 and 60 watts, respectively).
reflected power
1
forward power
reflected power
1
forward power
SWR
+
=
−
Summary of Contents for IntelliTuner -991
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