MFJ MFJ-868B - Power Measurement Scales

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
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nstruction
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3
Power Measurement Scales
1. The MFJ-868B Giant SWR/Wattmeter has three power scales. Refer to Figure 2
below for scale location and scale mark representation.
2. The meter’s full-scale forward and reflected power range is controlled by the
20W / 200W / 2kW slide switch. Select between 20, 200 or 2000 Watts. If your
transmitter/amplifier runs less than 20 Watts of output power, push the slide
switch all the way to the left for the 20-Watt scale. If your transmitter/amplifier
runs more than 20 Watts but less than 200 Watts of output power, push the slide
switch to the middle position for the 200-Watt scale. If your transmitter/amplifier
runs more than 200 Watts of output power, push the slide switch all the way to the
right for the 2000-Watt scale.
3. On the 2kW scale, each tall picket (scale mark) represents 100-Watts below the
500 Watt picket and 500 Watts above the 500 Watt picket. The short pickets
represent 50 Watts below the 500 Watt picket and 100 Watts above the 500 Watt
picket
4. On the 200W scale, each tall picket represents 10-Watts below the 50 Watt picket
and 50 Watts above the 50 Watt picket. The short pickets represent 5 Watts below
the 50 Watt picket and 10 Watts above the 50 Watt picket
5. On the 20W scale, each picket represents 1-Watt.
6. The most accurate power readings occur in the upper half of the meter scales.
When trying to measure power with a less than perfect match, the reflected power
should be subtracted from the forward power reading in order to find the true
power
Figure 2: Power and Standing Wave Ratio Scales for MFJ-868B Giant SWR/Wattmeter