MFJ-868B Giant True Peak Reading SWR/Wattmeter 1.8-60 MHz
Instruction 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.
