MFJ MFJ-941E User Manual
MFJ-941E Versa Tuner II
MFJ VERSA TUNER II
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 W atts of transmitter RF output power.
The MFJ-941E employs a cross-needle m eter so forward power, reflected power and SW R may
be read simultaneously.
CROSS-NEEDLE SWR/WATTMETER:
The meter on the MFJ-941E may be used alone or with the tuner. Set the
SELECTOR
to
COAX 1 DIRECT
or
COAX 2 DIRECT
ANTENNA
to use the meter without the tuner. T he
MFJ-941E utilizes a cross-needle meter so FORW ARD power, REFLECTED power and SWR
may be read simultaneously in two ranges. FORW ARD power m ay be read by setting the power
range switch to HI (
Watts) or LO (30 W atts). Next read the power level on the FORWARD
300
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
Watts FORWARD and 60 Watts REFLECT ED.
300
The LO range is 30 Watts F ORWARD and 6 Watts REF LECT ED. 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 coax ial plug with the center conductor of the plug c onnected 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
LINE, COAX 1
, and
operation. An external 50 Ohm dummy load can be connected to the
COAX 2
switch utilizes eight positions. They are
positions for both
BYPASS
(direct) and
DUMMY LOAD, BALANCE
TUNED
(through) the tuner
EXT LOAD
connector
located at the rear of the tuner. Do not continuously key into the dumm y load f or more than 2
minutes at a time.
CAUTION:
Never use the MFJ-941E for
DIRECT
or
DUMMY LOAD
positions.
OVER 300 Watts
of RF output power, even in the
1
MFJ-941E Versa Tuner II
INSTALLATION:
The tuner should be placed in a location where operation will be convenient. The ceram ic
1.
feed through insulators will have high RF voltages if r andom wire or balanced line operation
is used. These voltages can cause serious RF burns if touched when transmitting.
NOTE
:
2.
3.
4.
Locate the tuner so the rear is not accessible during operation.
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
the back of the tuner.
TRANSMITTER
connector on
One or two coax-fed antennas m ay be connected to the SO-239 coax connectors mark ed
COAX 1
or
COAX 2
transmitter, bypassing the tuner, by setting the
DIRECT
or
COAX 2 DIRECT
. Coax 1 and Coax 2 antennas may be connected directly to the
ANTENNA SELECTOR
switch to
, respectively.
A random wire antenna may be connected to the five-way binding post marked
random length wire should be long, high, and as clear of surrounding objects as possible.
For optimum oper ation, the wire antenna should be a quarter wave-length or longer at the
operating frequency. Do NOT ground the r andom wire antenna. The tuner s hould be wellÂgrounded to the transmitter. A binding post marked
connections.
A balanced line-fed antenna may be connected to the two five-way binding posts marked
5.
BALANCED LINE
. A jumper wire from the
binding post, as indicated by a dotted line
WIRE
GROUND
on the MFJ-941E, should be connected to one of the posts of the
couples the MFJ-941E to the balanced line through a 4:1 balun.
NOTE
:
6.
Either a balanced line or a random wire antenna m ay be connected to the MFJ-941E at
one time. If a random length wire is used, care should be taken to assure that no
jumper wire is between the
An external 50 Ohm dum m y load may be connected to the
binding post and the
WIRE
BALANCED LINE
EXT. DUMMY L OAD
is provided for ground
BALANCE LINE
.
located at the rear of the tuner.
COAX 1
. The
WIRE
. This
connector
2
Loading...