MFJ MFJ-860 User Manual

MFJ-860 SWR/Wattmeter Instruction Manual

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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.

SWR = 1+

Pr = Reflected Power
Pf = Forward Power

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Pr
Pf

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MFJ-860 SWR/Wattmeter Instruction Manual

Parts List

Designator Part Number Description
R1, R2 100-0003
R3, R6 133-4100
R4, R5 133-5100
R7 101-1680
R8 100-3330
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

Resistor, 1/4 Watt, 5%, Film, 100 Ω
Resistor, Trimpot, Sub. Horz., 10 kΩ
Resistor, Trimpot, Sub. Horz., 100 kΩ
Resistor, 1/2 Watt, 5%, Film , 68 Ω
Resistor, 1/4 Watt, 5%, Film, 3.3 kΩ

Schematic

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