MFJ-998 Legal Limit IntelliTuner Automatic Antenna Tuner
Instruction Manual
©
2007-2010 MFJ Enterprises, Inc.
7
•
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. One beep indicates
bypass mode, where RF from the transmitter goes directly to the antenna with no matching. A second
quick press toggles the tuner back to its last L/C setting, and the tuner responds with two beeps.
Note: Always connect the amplifier enable line from your transceiver output through the MFJ-
998 to the amplifier. This always ensures that the amplifier will be taken off-line prior to
any tuning events.
Press [TUNE] for 0.5 to 2 seconds to start the automatic tuning process. Tuning starts when [TUNE]
is released after the 0.5-2 second hold-time. The transmitter must be keyed first with at least five
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.
Note: You can reverse the two functions above by pressing and holding the [TUNE] button for
approximately 10 seconds. I.e., when the [TUNE] button is pressed and held for 10
seconds. You will hear two beeps. Now pressing [TUNE] momentarily starts the tuning
process, and pressing and holding the [TUNE] button for 0.5-2 seconds puts the tuner
into the bypass mode.
“
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, a bar appears
on top of the Auto/Semi indicator and the tuning process starts automatically when the transmitter is
keyed with at least five 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. One beep indicates on and two beeps indicate off. Default is off.
Automatic/Semi-Automatic Tuning Mode
Pressing [TUNE] and [ANT] simultaneously toggles between automatic and semi-automatic tuning
mode. In automatic mode, the tuning routine is automatically started when at least five watts of
power is applied and the SWR is a preset amount above the preset target SWR. In semi-automatic
mode, the tuning routine starts only when the [TUNE] button is pressed for 0.5 to 2 seconds. The
Auto/Semi indicator on the main display indicates the selected mode. Refer to Figures 16 and 17 for
the on-screen Auto/Semi indicator.
Note: During the 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.
•
POWER Button:
Used to turn the power on and off. When the power is off, the tuner is bypassed
(straight through from TRANSMITTER to ANTENNA 1 and WIRE) and the amplifier bypass
control line is uninterrupted by the MFJ-998. 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. Also, the target SWR appears on the main screen.
WARNING: Do not turn the power on and off rapidly, otherwise the tuner setting memory
can be corrupted and the unit will have to be reset to factory defaults.
Note: When the tuner power is OFF, the tuner is bypassed and RF from the transmitter goes
directly to ANTENNA 1 with no matching.