MFJ-991B IntelliTuner Automatic Antenna Tuner
Instruction Manual
2005-2012 MFJ Enterprises, Inc.
5
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-watt mark when
the capacitor is on the transmitter side. Reflected needle bounces to the 5-watt mark
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
μ
H. The upper limit of inductance, dependent on
frequency, is restricted to limit the maximum voltage and current across the tuner’s components.
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.
Note:
During the automatic tuning process, the tuner will make some noise. These are the
relays switching at a very high rate and this is normal. Do not be alarmed.
•
TUNE Button:
Has three different functions based on the length of time you press and hold it before
releasing. Press [TUNE] quickly (less than 0.5 second) to bypass the tuner. RF from the transmitter
goes directly to the antenna with no matching.
Press and hold [TUNE] for 0.5-2 seconds to start the automatic tuning process. The transmitter must
be keyed first with at least two watts of power. When the SWR is already below the target SWR,
pressing [TUNE] will fine-tune the match for a lower SWR if possible.
StickyTune
TM
allows for one-handed tuning operation. Normal tuning requires keying the transmitter
with one hand and using the other hand to push the [TUNE] button to start the tuning process unless a
transceiver interface cable is installed. When
StickyTune
TM
is enabled, the tuning process starts
automatically when the transmitter is keyed with at least two watts of power regardless of the SWR.
This works in both automatic and semi-automatic modes. To toggle the
StickyTune
TM
mode on and
off, press and hold the [TUNE] button for two seconds. The reflected power needle goes to 60-watt
mark when on and to 5-watt mark when off. Default is OFF.
Note:
StickyTune
TM
is disabled after tuning or power cycle.
Note:
If an amplifier is in-line, it should always be bypassed prior to tuning.
•
POWER Button:
Used to turn the power on and off. Note that during power-on the analog meter
bounces once to indicate the model 99
1
. When the power is off, the tuner is bypassed (straight
through from TRANSMITTER to ANTENNA and WIRE). When power is turned on, the tuner
powers-up bypassed, but will revert to the last stored matching values or begin tuning on application
of RF power when the TUNE button is pressed – or if Automatic or Sticky-Tune is enabled.
WARNING:
Do not turn the power on and off rapidly, otherwise the tuning setting
memory can be corrupted and the unit will have to be reset to factory defaults.
