MFJ-993B IntelliTuner Automatic Antenna Tuner
Instruction Manual
2005-2012 MFJ Enterprises, Inc.
5
The SWR is measured at the point where the two needles cross. See “SWR/Wattmeter” on page 12
for more detailed information.
•
LCD Display:
A 2-line by 16-character alphanumeric display. It displays the tuner’s various menus
and status. The display contrast can be adjusted by the [LCD] control on the front panel. Below the
display are the SWR and power bar meter scales. Refer to Figures 13 and 14 for descriptions of the
various displayed information.
•
LCD Contrast Control:
A trimpot control that adjusts the contrast of the LCD display. Use a small
flat blade screwdriver and turn clockwise to increase contrast.
•
ANT Button:
Used to select the antenna to tune. Button
out
selects
Antenna 1; button
in
selects
Antenna 2. The Antenna indicator on the main display indicates the selected antenna. A balanced
feedline or a single-wire antenna is, by default, Antenna 1. Changing the [ANT] button will switch
the antenna
only
when there is no RF power; also, the tuner setting for the selected antenna, if
available, is instantly restored from memory when enabled.
•
MODE Button:
Time-sensitive and used to navigate through the various main menus and to enter or
exit the setup menus.
•
C-UP and C-DN Buttons:
Used to manually increase or decrease the capacitance of the L-network
matching circuit. The capacitance range is 0 to 3908 pF (picofarads). The upper limit of capacitance,
dependent on frequency, is used to limit the maximum voltage and current across the tuner’s
components. This limit can be removed in the LC Limit setup menu, but is not recommended.
Note:
Pressing [C-UP] and [C-DN] simultaneously toggles the capacitor between the input
and output sides of the L-network. Forward needle bounces to the 30 watts when the
capacitor is on the transmitter side. Reflected needle bounces to the 5 watts when the
capacitor is on the antenna side.
•
L-UP and L-DN Buttons:
Used to manually increase or decrease the inductance of the L-network
matching circuit. The inductance range is 0 to 24.86
μ
H (microhenries). The upper limit of
inductance, dependent on frequency, is used to limit the maximum voltage and current across the
tuner’s components. This limit can be removed in the LC Limit setup menu, but is not recommended.
Shortcut:
Press both [L-UP] and [L-DN] buttons simultaneously to toggle SWR Beep on and
off. See “SWR Beep Menu” on page 20.
Note:
Pressing [C-DN] and [L-DN] simultaneously places the tuner in bypass mode. The
reflected meter needle momentarily bounces to the 20-watt mark to indicate this. RF
from the transmitter goes directly to the antenna with no matching.
•
AUTO Button:
Used to select automatic or semi-automatic tuning mode. Button
out
selects
automatic mode – the tuning routine is automatically started when 2-10 watts of power is applied and
the SWR is a preset amount above the preset target SWR. Button
in
selects the semi-automatic mode
– the tuning routine starts only when the [TUNE] button is pressed for 0.5-2 seconds. The Auto/Semi
indicator on the main display indicates the selected mode.
