MFJ-998 Legal Limit IntelliTuner Automatic Antenna Tuner
Instruction Manual
©
2007-2010 MFJ Enterprises, Inc.
22
Manual tuning of inductance is similarly accomplished, using [L-UP] and [L-DN]. Since the capacitance
and inductance are interdependent, some back-and-forth between the two may be needed, just as in a
conventional tuner with knobs.
Pressing [C-UP] and [C-DN] simultaneously moves the capacitance back and forth from one side of the
inductance to the other. The L-Network menu displays the capacitance on the left to indicate that the
capacitance is on the antenna side (corresponding with the rear panel configuration of connectors); the
capacitance value moves to the right side of the display when the capacitance is on the transmitter side of
the inductance. A general rule of thumb is that loads with impedance higher than 50 ohms call for the
capacitance on the antenna side; loads with impedance lower than 50 ohms call for the capacitance on the
transmitter side.
Pressing [C-DN] and [L-DN] simultaneously or pressing [TUNE] quickly places the tuner in bypass
mode; i.e. zero inductance and zero capacitance. RF from the transmitter goes directly to the antenna
with no matching. One beep indicates changing to bypass mode. Also, the decimal point in the SWR
reading is replaced with a comma to indicate bypass mode.
Pressing [TUNE] and [ANT] simultaneously toggles between automatic or 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. The Auto/Semi indicator on the main display
indicates the selected mode.
Pressing [TUNE], [C-DN] and [L-DN] simultaneously overwrites the tuner memory with the current
tuner setting. Settings with SWR greater than 3.0 will not be stored. One beep indicates memory
overwrite.
Morse Code and Beeps
If insufficient power is applied for tuning (less than five watts), the display will flash
INCREASE
POWER
three times and “QRO” (dah-dah-di-dah di-dah-dit dah-dah-dah) will be sent on CW. Increasing
the input power above five watts ends this message.
When input power is too high, the tuner enters a self-protection mode. The tuner will not allow any of its
relays to change to prevent damage to your tuner.
If too much power is applied when tuning, the tuner will cease the tuning routine, flash
DECREASE
POWER
three times and send “QRP” (dah-dah-di-dah di-dah-dit di-dah-dah-dit) on CW. This occurs
when the forward power exceeds 75 watts and the SWR is greater than 3.0, or when the forward power
exceeds 125 watts regardless of the SWR.
If more than 1500 watts is applied to the tuner, the tuner will go into bypass mode, flash
OVERLOAD
three times and send “QRT” (dah-dah-di-dah di-dah-dit dah) on CW.
If the tuning process is activated under these conditions, the tuner will not start the tuning. It will display
a warning message on the LCD and send the appropriate code on CW. The following table shows the
various tuner beeps: