
MFJ-939 Plug&Play IntelliTuner Automatic Antenna Tuner
Instruction Manual
2006-2015 MFJ Enterprises, Inc.
8
General Tuner Setup and Cabling
The MFJ-939 comes with the interface cable and the jumpers preset to allow for a quick “Plug and Play”
setup.
1
With the radio off connect the interface cable to the radio and MFJ-939.
2
Connect the antenna to the Antenna coax connector as listed on page7.
3
Connect the RF line from the radio coax connector to the MFJ-939 Radio coax connector as
listed on page 7.
4
Ground the unit. See the Grounding Hints section on page 25.
5
Turn on the tuner first then the radio.
6
Follow the radio instruction manual for setting up the operation of an external tuner. See the
Operation, Radio Interface, and Connection information sections for additional details for the
radios listed below.
As the station changes the tuner can be reconfigured as listed in the Interface section of each model to
function with other radios by replacing the interconnect cable and changing jumpers in the tuner.
Figure 6
General Setup
Modification to Change Radio Model
Changing the MFJ-939 to use with another model of radio is not difficult to do. For the radio model you
are changing to obtain the proper interface cable and change the jumpers in the tuner to the positions
needed for the new radio. See the section Radio Interface and Connections under the new radio you are
changing to for interface model and jumper settings.