MFJ MJF-941E Quick Start Manual

MFJ-941E

GENERAL INFORMATION

The MFJ-941E is designed to match virtually any transmitter to any antenna, including dipoles, inverted-
vees, verticals, mobile whips, beams, random wires, and others fed by coax lines, balanced lines or a
single wire. An eight-position antenna-selector switch provides versatile antenna selection. The MFJ-
941E will handle up to 300 Watts of transmitter RF output power. The MFJ-941E employs a cross-
needle meter so forward power, reflected power and SWR may be read simultaneously.

CROSS-NEEDLE SWR/WATTMETER

The meter on the MFJ-941E may be used alone or with the tuner. Set the ANTENNA SELECTOR to
COAX 1 DIRECT or COAX 2 DIRECT to use the meter without the tuner. The MFJ-941E utilizes a
cross-needle meter so FORWARD power, REFLECTED power and SWR may be read simultaneously in
two ranges. FORWARD power may be read by setting the power range switch to HI (300 Watts) or LO
(30 Watts). Next read the power level on the FORWARD SCALE. REFLECTED power is shown
simultaneously on the REFLECTED SCALE. SWR is determined by observing the intersection point of
the two needles. No SWR sensitivity adjustment is needed to read SWR. The HI range is 300 Watts
FORWARD and 60 Watts REFLECTED.
REFLECTED. The difference between the HI and LO scales readings is a factor of 10.
The meter lamp can be powered by a 12 Vdc source, such as the optional MFJ-1312B power supply. Use
a 2.1mm coaxial plug with the center conductor of the plug connected to the positive and the sleeve
connected to ground. The METER LAMP ON/OFF switch will activate the meter lamp.

ANTENNA SELECTOR

The ANTENNA SELECTOR switch utilizes eight positions. They are DUMMY LOAD, BALANCE
LINE, COAX 1, and COAX 2 positions for both BYPASS (direct) and TUNED (through) the tuner
operation. An external 50 Ohm dummy load can be connected to the EXT LOAD connector located at
the rear of the tuner. Do not continuously key into the dummy load for more than 2 minutes at a time.
CAUTION: Never use the MFJ-941E for OVER 300 Watts of RF output power, even in the
DIRECT or DUMMY LOAD positions.
Installation:
The tuner should be placed in a location where operation will be convenient. The ceramic feed
1.
through insulators will have high RF voltages if random wire or balanced line operation is used.
These voltages can cause serious RF burns if touched when transmitting.
NOTE: Locate the tuner so the rear is not accessible during operation.
2. The MFJ-941E should be installed between the transmitter and antenna. A coaxial line should be
connected to the transmitter and the SO-239 coax TRANSMITTER connector on the back of the
tuner.
3. One or two coax-fed antennas may be connected to the SO-239 coax connectors marked COAX 1
or COAX 2. Coax 1 and Coax 2 antennas may be connected directly to the transmitter, bypassing
the tuner, by setting the ANTENNA SELECTOR switch to COAX 1 DIRECT or COAX 2
DIRECT, respectively.
MFJ VERSA TUNER II
The LO range is 30 Watts FORWARD and 6 Watts
Versa Tuner II
1