MFJ MFJ-941E Скачать руководство пользователя

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MFJ-941E Versa Tuner II

If a SWR of

1:1

is not achieved, the

INDUCTOR

control should be increased or decreased

and

Step

repeated. If arcing should occur between capacitor plates, the

INDUCTOR

control should be increased or decreased by one position, and

Step

repeated. If SWR of

1:1

cannot be achieved,

Step

should be repeated for each

INDUCTOR

control position.

After a minimum SWR is achieved, transmitter power may be increased to 300 Watts.
The

VERSA TUNER II

will reduce the SWR of most feed systems to

1:1

. In some cases,

1:1

SWR is not achievable. In such cases, the length of the antenna may be increased

or decreased to improve SWR.

SWR of

1:1

may occur at more than one set of control settings on the

MFJ-941E

. When

an SWR of

1:1

is obtained, make sure that the transmitter power is relatively high. If

transmitter power has decreased substantially, try another

INDUCTOR

control setting and

repeat

Step

In Case Of Difficulty:

If this tuner

fails to tune,

please

double check all connections

and follow the tuning procedures 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 frequency. If you are still unsuccessful, please read the

Antenna

Matching Problems

text below.

Note
:

If this tuner

arcs

when operating on the

160 meter

band, it may be necessary to

reduce

transmitter output power

Antenna Matching Problems:

Most matching problems occur when the antenna system presents an

extremely high impedance to the tuner

. When the

antenna impedance is much

lower

than the feedline impedance, an

odd quarter-wavelength

feedline converts the low

antenna impedance to a

very high impedance at the tuner

. A similar problem occurs if the antenna has an extremely

high impedance and the transmission line is a multiple of a half-wavelength. The half-wavelength line

repeats

the very

high antenna impedance at the tuner.

Incorrect feedline and antenna lengths can make an antenna system very

difficult or

impossible

to tune.

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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