MFJ MFJ-860 User Manual

MFJ-860 SWR/Wattmeter

Instruction Manual

MFJ-860 HF SWR/Wattmeter

The MFJ-860 HF SWR/Wattmeter measures forward and reflected power and indicates SWR for the ham bands from 160 meters to 6 meters. The MFJ-860 has 2 power scales which are selected with the front panel push button switch. The low power scale reads from 0-30 watts forward and 0-6 watts reflected. The high power scale reads from 0-300 watts forward and 0-60 watts reflected. SWR is indicated from 1:1 to ∞ .

Connections

Connect your transmitter to the connector labeled "TRANSMITTER" and your antenna to the connector labeled "ANTENNA". It is important that you use good quality coax and properly installed connectors.

If you want to measure the power output capability of a transmitter/amplifier you should connect a quality dummy load (50 ohms) to the antenna jack of the MFJ-860.

Caution: many HF dummy loads exhibit SWR especially on 15 and 10 meters.

The MFJ-860 has an illuminated meter. To provide power for the meter lamp, 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-860

To measure forward and reflected power press the selector switch to the correct power setting. Transmit a steady carrier and read the power from the meter. Each unmarked picket on the scale is an even division between the adjacent marked values. SWR is read from the SWR curve closest to where the meter needles cross.

If a more exact reading of SWR is needed you may use the equation for SWR. Measure the forward and reflected power then put the values into the following equation.

F	Pr I F	Pr I
G	J G	J
SWR = 1+	1-
H	Pf K H	Pf K

Pr = Reflected Power

Pf = Forward Power

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MFJ-860 SWR/Wattmeter		Instruction Manual
Parts List
Designator	Part Number	Description
R1, R2	100-0003	Resistor, 1/4 Watt, 5%, Film, 100 Ω
R3, R6	133-4100	Resistor, Trimpot, Sub. Horz., 10 kΩ
R4, R5	133-5100	Resistor, Trimpot, Sub. Horz., 100 kΩ
R7	101-1680	Resistor, 1/2 Watt, 5%, Film , 68 Ω
R8	100-3330	Resistor, 1/4 Watt, 5%, Film, 3.3 kΩ
C1-C4	200-0004	Capacitor, Disc Ceramic, 25/50v, 20%, .01 uF
C5	200-0010	Capacitor, Disc Ceramic, 50V, 20%, 220 pF
C6	204-0001	LLT, Capacitor, Trimmer, 250V,3-10 pF
L1	401-0037	Inductor, Molded, .3", 10%, brn-blk-gld, 1.0uH
D1-D2	300-2835	Diode, Schottky, HP2835
for M1	715-6186	Spacer, Aluminum, Hex, 4-40-1/4"L, .25" Od, Plain
for M1	710-6050	Washer, Metal, Lock Washer, #6 Id, Int. Tooth
for M1	700-2221	Screw, Machine, Pan, Phillips, 4-40-1/4", St, BK
for M1	736-0100	Bracket, Tab, Meter,
J1, J2	610-2005	Connector, UHF, 4-Hole Mount, SO-239
J3	601-6121	Jack, Coaxial, 2.1mm, Ch. Mt., Closed, Mono
M1a&M1b	400-3084	Meter, Cross Needles, 200uA, 1200 Ohm, 300W

Schematic

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