MFJ MFJ-873, MFJ-872, MFJ-874 User Manual
MFJ Enterprises, Inc.
300 Industrial Park Rd
Starkville, MS 39759 USA
MFJ-872, MFJ -873, & MFJ-874
SWR & Power Meter Instruction Manual
This SWR & Power meter is a highly accurate RF meter for measuring Forward Power,
Reflected Power, and VSWR.
Main Features:
• Large meter display for easy reading.
• Forward RF power readings, switchable to indicate either average power of Peak
Envelop Power (PEP) for SSB and AM transmitters.
• Reflected RF power readings.
• VSWR ratios.
• Illuminated meter.
• Convenient control for easy operation.
Model MFJ-872 MFJ-873 MFJ-874
Frequency Range 1.8 - 200 MHz 125 - 525 MHz 1.8 - 525 MHz
Power Range 1W to 200W
Power Scale 5W, 20W, 200W
Maximum Power 200W
Accuracy 5W Range +/- 10% (AVG)
+/- 15% (PEP)
20W-200W Range +/- 5% (AVG)
+/- 10% (PEP)
VSWR Min Power required = 1 Watt for F.S.D.
Input/Ou tput Impedance 50 Ohms
Input/Output Connectors SO-239
Dimensions (W/H/D) in 7.5 X 3.35 X 5.3
Weight (lbs) 1.76
Accessories Instruction Manual & Lead wire with DC Plug
Front Panel
Back Panel
Explanation of Features:
1. Meter Display: Indicates Forward/Reflected Power in Watts and SWR ratio.
2. Function Switch: Selects Forward Power, Reflected Power , SWR SET, SWR.
3. Range Switch: Selects RF Power Ranges of 5W, 20W, and 200W.
4. SWR SET Control Knob: Sets full scale deflection when measuring V SWR.
5. AVG/PEP Monitor: Selects Average or PEP RF Power Readings.
6. Meter Zero adjust: Mechanical zero adjustment for meter needle.
7. TX Connector (125 - 525 MHz): Coax connector to transmitter 50 Ohm RF output.
8. ANT Connector (125 - 525 MHz): Coax connector to 50 Ohm antenna system.
9. 13.8V DC connection for meter illumination.
10. HF/V.UHF BAND Selector Switch. (MFJ-874 only)
11. TX Connector (1.8 - 200 MHz): Coax connector to transmitter 50 Ohm RF output.
(MFJ-874 only)
12. ANT Connector (1.8 - 200 MHz): Coax connector to 50 Ohm antenna system. (MFJ-
874 only)
Note: If meter lighting is required, use the DC cable enclosed and connect it to a 13.8V DC
source.
FORWARD POWER MEASUREMENT
1. Set the FUNCTION switch to the ‘FWD’ position.
2. Set the radio transceiver to transmit and read the scale corresponding to the Power
range selected (5W, 20W, or 200W)
3. When the AVG/PEP button is ‘out’ the meter reads average RF power. When the
AVG/PEP button is depressed the meter reads Peak Envelope Power for use with SSB
and AM transmissions. In this mode there will be a slow rise and decay time.
REFLECTED POWER MEASUREMENT
1. Set the FUNCTION switch to the ‘REF’ position.
2. Set the radio transceiver to transmit and read the scale corresponding to the Power
range selected (5W, 20W, or 200W)
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