MFJ MFJ-868B User manual

INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
MFJ ENTERPRISES, INC.
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]
COPYRIGHT 2013 MFJ ENTERPRISES, INC.
C
Model MFJ-868B
VERSION 1A
MODEL
MFJ-868B
M
FJ True Peak-Reading SWR/Wattmeter
1.8-60MHz
Giant

DISCLAIMER
Information in this manual is designed for user purposes only and is not intended to
supersede information contained in customer regulations, technical manuals/documents,
positional handbooks, or other official publications. The copy of this manual provided to
the customer will not be updated to reflect current data.
Customers using this manual should report errors or omissions, recommendations for
improvements, or other comments to MFJ Enterprises, 300 Industrial Park Road,
Starkville, MS 39759. Phone: [phone]; FAX: [phone]. Business hours:
M-F 8-4:30 CST.
NOTE: The meter must have a power source in order to function. Power
can be provided b
y
an external 12 VDC suppl
y
(ne
g
ative
g
round onl
y
) or an
internal nine-volt “transistor radio” battery.
IMPORTANT: When using the external 12VDC supply, to
prevent possible shorting of the power supply, plug in the supply
to the jack before turning the power on to the power supply.

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
1
MFJ-868B Giant SWR/Wattmeter
Introduction
The MFJ-868B Giant SWR/Wattmeter is the World’s Largest HF SWR/Wattmeter.
The MFJ-868B measures peak or average forward and reflected power as well as
standing wave ratio. It is designed to operate on 1.8-60 MHz. The MFJ-868B has three
power scales, which are selected with the front panel slide switch. The high power scale
measures 0-2000 Watts forward or reflected power. The mid power scale measures 0-200
Watts forward and reflected power. The low power scale measures 0-20 Watts forward
and reflected power. MFJ’s exclusive Power Saver circuit turns the meter on only when
RF power is being measured. The MFJ-868B utilizes a large illuminated 6.5-inch Single-
Needle meter to read the SWR from 1:1 to ∞.
Features
• Huge Backlit Meter: 6.5 in. measured diagonally across the front.
• Easy-to-Read Scales: Large numbers and pickets make reading a breeze.
• Power Saver Circuit: Meter turns on only when transmitting.
• Three Power Scales: 20/200/2000 Watt power scales.
• Forward and Reflected: Measures forward power and reflected power.
• Peak or Average Reading: Measures Peak or Average power.
• Power or SWR: Measures Power and SWR.
• Easy-to-Set SWR: Easy set for accurate SWR measurements.
• Frequency Range: 1.8 - 60 MHz.
• Input/Output Impedance: 50 Ohms.
FWD SET
PEAK REF SWR
AVG
20W
200W
2kW
PWR
SWR
MFJ SWR/Wattmeter Giant
MFJ-868 OFF
MAXMIN
ON
S
WR SET
Figure 1: Controls
Controls
1. 20W / 200W / 2kW switch: Selects between 20, 200, 2000-Watt power scales.
2. PEAK/AVG switch: Selects Peak or Average power measurement.
3. SWR/PWR switch: Selects Power or SWR measurement.
4. REF/FWD switch: Selects forward or reflected power measurement.
5. SWR/SET switch: Selects SWR measurement or set.
6. SWR SET knob: Sets full-scale deflection to measure SWR.
7. ON/OFF switch: Turns power to the unit and lamp on or off.

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
2
Installation
1. 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.
2. The meter must have a power source in order to function. Power can be
provided by an external 12 VDC supply such as the MFJ-1312D or an internal
nine-volt “transistor radio” battery. Use a 2.1 mm coaxial plug with the center
conductor positive and the sleeve ground. MFJ’s exclusive Power Saver circuit
turns the meter on only when RF power is being measured.
3. An internal lamp backlights the meter scale. The lamp requires a 12 VDC supply
such as the MFJ-1312D. Use a 2.1 mm coaxial plug with the center conductor
positive and the sleeve ground. The ON/OFF switch turns the unit and internal
lamp on or off.
4. To measure the power output capability of a transmitter/amplifier you should
connect a quality 50-ohm dummy load to the ANTENNA connector of the MFJ-
868B.
Operation
Power Measurement Settings
1. Set the SWR/PWR switch to PWR (out) for power measurement.
2. Set the REF/FWD switch to FWD (out) for forward power measurement or to
REF (in) for reflected power measurement. (REF/FWD and SWR/SET settings
share the same switch.)
3. Select peak or average reading by setting the PEAK/AVG switch to the desired
position. Set to AVG (out) to read average RF power. Set to PEAK (in) for use
with SSB and AM transmissions. In this mode, there will be a slow rise and
decay time.
Note: The meter must have a power source in order to function. Power
can be provided b
y
an external 12 VDC suppl
y
(ne
g
ative
g
round onl
y
) or an
internal nine-volt “transistor radio” battery.

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
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

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
4
SWR Measurement Settings
1. Set the SWR/PWR switch to SWR (in) for standing wave ratio measurement.
2. Set the SWR/SET switch to the SET (out) position in order to set the full-
scale deflection to measure SWR. (SWR/SET and REF/FWD settings share
the same switch.)
3. Set the radio transceiver to transmit mode and transmit the desired power
output.
4. Slowly turn the SWR SET knob clockwise towards MAX until the meter
point is at the SET position on the SWR scale. If the meter point goes past
the SET position, slowly turn the SWR SET knob counter-clockwise
towards MIN until the meter point is at the SET position on the SWR scale.
5. Set the SWR/SET switch to the SWR (in) position while transmitting. The
meter will now indicate the standing wave ratio. Note: The SWR SET knob
must be reset when the power level is changed. As you increase the power,
the knob will need to be turned counter-clockwise towards MIN. This will
maintain an accurate SWR reading.
SWR Measurement Scale
1. The MFJ-868B Giant SWR/Wattmeter has one standing wave ratio scale.
Refer to Figure 2 above for scale location and scale mark representation.
2. On the SWR scale, each tall picket represents 0.5 units below the 2 picket and
1 unit above the 2 picket.
3. The short pickets represent 0.1 units below the 2 picket and 0.5 units above
the 2 picket.
4. The red shaded area represents a SWR of greater than 3:1. It is not
recommended to operate within this shaded area of a SWR greater than 3.0:1.

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
5
Calibration
The MFJ-868B has been calibrated at the factory. If it should ever need to be
recalibrated, then follow this procedure:
Equipment Needed
1. Transmitter capable of supplying enough power to obtain ½ to full-scale reading
at 14 or 21 MHz.
2. 50-ohm dummy load that is capable of handling full transmitter output power and
has better than a 1.15:1 SWR.
3. Power meter of know accuracy. The calibration will only be as good as the
standard reference meter.
4. 50-ohm cables capable of handling the power. RG-58/u is recommended. DO
NOT USE RG-59 or RG-11.
Meter Calibration
1. Refer to Figure 3 for the Calibration Setup and Figure 4 for trim pot location.
2. Connect the Calibration Setup equipment as shown in Figure 3. Use a 50-ohm
dummy load for the antenna. Set the Transmitter to the 14 MHz in the 20-meter
band.
3. With the 20W / 200W / 2kW switch on the 20 Watt scale, transmit 20 Watts as
indicated on the reference meter. Adjust the 20 trim pot on the inside board to set
the forward power scale to 20 Watts. Refer to Figure 4 for trim pot location.
4. With the 20W / 200W / 2kW switch on the 200 Watt scale, transmit 200 Watts as
indicated on the reference meter. Adjust the 200 trim pot on the inside board to
set the forward power scale to 200 Watts. Refer to Figure 4 for trim pot location.
5. With the 20W / 200W / 2kW switch on the 2000 Watt scale, transmit 2000 Watts
as indicated on the reference meter. Adjust the 2000 trim pot on the inside board
to set the forward power scale to 2000 Watts. Refer to Figure 4 for trim pot
location.
6. Calibration is complete. Reflected power and standing wave ratio do not need
calibration. Setting the forward power also sets the reflected power and SWR.

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
6
Figure 3: Calibration Setup
Figure 4: Trim pot location (inside view)
Transmitter/
Transceiver
Standard
Reference
Wattmeter
MFJ-868B
Giant
SWR/
Wattmeter
50-Ohm
Dummy Load
20W / 200W / 2KW
switch
PEAK/AVG
switch SWR/PWR
switch REF/FWD
SWR/SET
switch
ON/OFF
switch
20W TRIMPOT
200W TRIMPOT
2000W TRIMPOT

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
7
Technical Assistance
If you have any problem with this unit first check the appropriate section of this manual.
If the manual does not reference your problem or reading the manual does not solve your
problem, you may call MFJ Technical Service at 662-323-0549 or the MFJ Factory at
662-323-5869. You will be best helped if you have your unit, manual and all information
on your station handy so you can answer any questions the technicians may ask.
You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial Park Road,
Starkville, MS 39759; by Facsimile (FAX) to 662-323-6551; or by email to
[email protected]. Send a complete description of your problem, an
explanation of exactly how you are using your unit, and a complete description of your
station.
Notes

MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
I
nstruction
M
8
Schematic