MFJ-994B IntelliTuner Automatic Antenna Tuner
Instruction Manual
©
2004-2010 MFJ Enterprises, Inc.
11
SWR/Wattmeter
The backlit cross-needle meter measures forward power,
reflected power, and SWR, and operates whenever the tuner is
powered on. Forward power up to 3000 watts is displayed on
the left-hand FORWARD meter scale. Reflected power up to
600 watts is read on the right-hand REFLECTED meter scale.
For low-power tuning, meter ranges of 300 watts forward and 60
watts reflected are available. Multiply the readings on these
scales by ten when in the high power meter range.
The meter can be set to low, high, or auto range. Auto range
automatically sets the meter scales according to the input RF power to the tuner. Forward power greater
than 300 watts or reflected power greater than 60 watts automatically sets the meter to the high power
range. Forward power less than 250 watts and reflected power less than 40 watts automatically set the
meter to the low power range. To cycle the meter range among low, high, and auto range, press the
[TUNE] and [L-DN] buttons simultaneously. The forward needle will read “300” for high range, “30” for
low range, and “100” for auto range until the buttons are released.
SWR is calculated from the forward and reflected power
measurements as shown by the equation at the right. The SWR is
read from the eight red SWR curves, ranging from 1.0 to infinity,
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 9 shows an SWR
of approximately 2.0.
The meter also indicates various operational states of the tuner. Refer to “Tuner Status Indicators” on
page 15 for more details.
0
1
0
30
50
100
200 30
0
0
5
20
40
60
8
5.0
3.0 2.0
1.5 1
.2
Hi x1
Lo x.1
400-3083
1
10
Figure 9. SWR/Wattmeter.
reflected power
1
forward power
reflected power
1
forward power
SWR
+
=
−
