MFJ-939 Plug&Play IntelliTuner Automatic Antenna Tuner
Instruction Manual
2006-2015 MFJ Enterprises, Inc.
6
BACK PANEL
RADIO
INTERFACE
+
POWER
12VDC
750mA
M FJ ENTER PR ISES, INC .
STAR K V ILLE, M S USA
GROUND
TRANSMITTER
ANTENNA
Figure 4 MFJ-939 Back Panel.
•
Power:
This jack accepts a standard 2.1 × 5.5 mm coaxial plug with positive center and negative
sleeve. The tuner requires 12-15 volts DC at up to 750 mA. The use of a regulated supply is not
mandatory but is recommended for best performance. An optional 12 volts DC 1.5 amp power
supply, the MFJ-1316, is available from MFJ Enterprises, Inc.
WARNING:
Do not apply voltages
greater than 18 volts to this unit, or permanent damage may result.
Note:
When the tuner power is OFF, the tuner is bypassed and RF from the transmitter goes
directly to the antenna with no matching. When turned on, the tuner powers up in bypass
mode.
•
Radio Interface:
An 8-pin modular (RJ-45)
connector for connecting to the tuner interface
connector of compatible radios. Most radios
provide +13.8 VDC power thought its tuner
interface connector. If separate power supplies
are used to power the MFJ-939, the MFJ-939
should be powered on first (both LEDs blink
once) and then turn on the radio, so the radio
knows an external tuner is attached. The radio
will disable its internal tuner, if it has one, and
use the external tuner.
The Radio Interface works with radios that are compatible with Alinco EDX-2, Icom AH-3 and AH-
4, Kenwood AT-300, and Yaesu FC-30, FH-1 and FH-2. When connected to a compatible radio,
simply press the [TUNER] or [AT] button on the radio; for FH-1 or FH-2 compatible Yaesu, press the
[TUNE] button
on the
tuner
to start the automatic tuning process. The radio will automatically switch
to CW mode, transmit a low power (typically 10-30 watts) carrier, and start the tuning process. Once
the automatic tuning is completed, the radio will return to its previous mode and power setting.
WARNING:
Make sure the +13.8 volts connection on the radio’s tuner port is
capable of supplying the 750 mA of current required by the MFJ-939.
•
Transmitter:
SO-239 connector for coax cable from transmitter or transceiver
•
Ground:
Wing-nut terminal for RF ground wire connection.
•
Antenna:
SO-239 connector for coax cable from antenna.
Note:
To use a WIRE on the Antenna connector, be sure to use the enclosed adaptor.
+13.8 V DC input ( 50 mA)
+13.8 V DC input ( 50 mA)
+13.8 V DC input ( 50 mA)
Ground
Ground
Key/TT/TX
TX INH
Start/TS/RX
7
7
7
7
8
6
5
4
3
2
1
12345678
Rear Panel View
Figure 5 Interface Connector
