MFJ SWR/Wattmeter -864 HF/144/440 Manual

MFJ-862 SWR/Wattmeter
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MFJ-864 HF/144/440 SWR/Wattmeter

General Information:

The MFJ-864 HF/144/440 SWR/Wattmeter measures forward and reflected
power and indicates SWR for the 1.8 - 60, 144, and 440 MHz ham bands.
The MFJ-864 has 2 power scales for each band selected with the front panel
rotary switch. The low power scale reads from 0-30 watts forward and 0-6
watts reflected. The high power reads from 0-300 watts forward and 0-60
watts reflected. SWR is indicated from 1:1 to 5:1.

MFJ-864 Theory of Operation:

The MFJ-864 senses RF energy traveling along a 50 ohm stripline. A
forward and reflected stripline couple to the 50 ohm stripline to make a
directional coupler. A voltage is produced in the forward and reflected
striplines that is proportional to the current and voltage traveling along the 50
ohm stripline. This signal is rectified by a diode and smoothed by a capacitor.
Because the directional coupler's sensitivity increases with frequency,
trimpots are used to adjust for different frequency and power settings (high or
low power).

Connections:

Connect your HF transmitter and antenna to the 1.8 - 60 MHz HF Sensor
connectors labeled XMTR and ANT on the rear panel. Connect your
VHF/UHF transmitter and antenna to the 144 / 440 MHz VHF/UHF Sensor
connectors labeled TRANSMITTER and ANTENNA on the rear panel. It is
important that you use good quality coax and connectors that are
designed for HF and VHF/UHF!
If you want to measure the power capability of a transmitter/amplifier or to re-
calibrate the MFJ-864 you should connect a quality dummy load (50 ohms)
that is designed for VHF/UHF to the antenna jack.
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