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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 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

COAX 1 DIRECT

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

(

300

Watts) or

(

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

range is

300

Watts FORWARD and

Watts REFLECTED. The

range is

Watts FORWARD and

Watts REFLECTED. The

difference between the

and

scales readings is a factor of

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

DUMMY LOAD

positions.

Содержание MFJ-941E

Страница 1: ...vel 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 The LO range is 30 Watts FORWARD and 6 Watts REFLECTED The difference between the HI and LO scales readings is a factor of 10 The ...

Страница 2: ...e connected to the five way binding post marked WIRE The random length wire should be long high and as clear of surrounding objects as possible For optimum operation the wire antenna should be a quarter wave length or longer at the operating frequency Do NOT ground the random wire antenna The tuner should be well grounded to the transmitter A binding post marked GROUND is provided for ground conne...

Страница 3: ... be set to DUMMY LOAD for tuning up the transmitter NOTE The transmitter should always be tuned at a low output power After the transmitter is properly tuned the ANTENNA SELECTOR should be set to the desired antenna and the tuner adjusted for a minimum SWR as described below DO NOT readjust the transmitter loading control setting after loading it to 50 Ohms NOTE When using the MFJ 941E for receivi...

Страница 4: ...adjust TRANSMITTER and ANTENNA controls for minimum SWR Since both controls interact the two controls can best be adjusted by turning the TRANSMITTER control one small increment at a time then rotating the ANTENNA control for minimum SWR Repeat this process until minimum SWR is obtained ...

Страница 5: ...cedures again Be sure you are using enough inductance lowest letter usable for band and have the capacitors open far enough highest front panel number If this tuner arcs at the rated power levels please double check all connections and follow the tuning procedures again Be sure you are using the least amount of inductance and the greatest capacitance possible to match the load on the operating fre...

Страница 6: ...n wire line is used to feed a half wave 100 to 140 foot dipole The odd quarter wave line transforms the dipole s low impedance to over three thousand Ohms at the tuner This is because the mismatched feedline is an odd multiple of 1 4 wavelength long The line inverts or teeter totters the antenna impedance ...

Страница 7: ...d these lengths The worst possible line lengths are shown in brackets 160 meter dipole 35 60 170 195 or 210 235 feet Avoid 130 260 ft 80 meter dipole 34 40 90 102 or 160 172 feet Avoid 66 135 190 ft 40 meter dipole 42 52 73 83 112 123 or 145 155 feet Avoid 32 64 96 128 ft NOTE Some trimming or adding of line may be necessary to accommodate higher bands WARNING To avoid problems a dipole antenna sh...

Страница 8: ... INC P O Box 494 Mississippi State MS 39762 by FAX to 601 323 6551 through Compuserve at 76206 1763 or by email to 76206 1763 Compuserve com Send a complete description of your problem an explanation of exactly how you are using your unit and a complete description of your station ...

Страница 9: ...MFJ 941E Versa Tuner II 9 Schematic ...

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