MFJ-862 SWR/Wattmeter Instruction Manual
2
The MFJ-862 has a lighted meter. To provide power for the meter light, a 12 Vdc
supply such as the MFJ-1312B should be used. Use a standard 2.1 mm coaxial
plug with the center conductor positive and the sleeve ground.
Using the MFJ
Using the MFJUsing the MFJ
Using the MFJ-
--
-862
862862
862
To measure forward and reflected power turn the selector switch to the correct
frequency and power setting. Transmit and read the power from the meter. Each
unmarked hatch on the scale is an even division between the two marked
numbers. SWR is read directly from the scale where the meter needles cross.
If a more exact reading for SWR is needed you may use the equation for SWR.
Measure the forward and reflected power and put the values into the following
equation:
Calibration
CalibrationCalibration
Calibration
Note that the readings for forward and reflected power (and thus SWR) are less
accurate if the power levels you are reading are not near the calibration power
level or within the correct power range. For an accurate reading of 10 watts
forward use the low power scale. If your transmitter only transmits 10 watts, re-
calibrate the low power scale at 10 watts for maximum accuracy.
The MFJ-862 has been calibrated at the factory for 10 and 100 watts. If re-
calibration is necessary you will need a 50 ohm dummy load, good quality 50
ohm coax, and a transmitter of known power or another accurate wattmeter to
use as a standard.
Connect the transmitter to the TRANSMITTER
TRANSMITTERTRANSMITTER
TRANSMITTER connector and a good length of
coax between the ANTENNA
ANTENNAANTENNA
ANTENNA connector and the dummy load. Transmit at a
known power level and adjust the forward or reflected sensitivity pot, for the
power scale and frequency you are using, until the correct reading is shown on
the meter.
Power Forward =Pf
Power Reflected =Pr
Pf
Pr
-1
Pf
Pr
+1=SWR
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