MFJ-993B IntelliTuner Automatic Antenna Tuner
Instruction Manual
2005-2012 MFJ Enterprises, Inc.
30
Setting the Speaker Volume
To set the speaker volume, press and hold
both
the [L-UP] and [L-DN] buttons while turning the power
on. The message
SET VOLUME
will display and send as Morse code repetitively. Insert a small flat
blade screwdriver into the VOL hole on the front panel to adjust the volume level. Turn clockwise to
increase volume level. Turn the power off.
Wattmeter Calibration
To calibrate the meter needles, you will need a Phillips screwdriver and a tuning tool or small flat blade
screwdriver.
WARNING:
Never operate the MFJ-993B with its cover removed; dangerous voltages and
currents can be present during operation. Never exceed tuner specifications.
Note:
The trimmers involved in this calibration are located on the circuit board behind the front
panel; do not confuse these with the SWR bridge trimmers.
1.
Turn off the power to the tuner and the transmitter.
2.
Remove the cover from the tuner (12 screws) with a Phillips screwdriver.
3.
Press and hold
both
the [C-UP] and [C-DN] buttons while turning the power on.
4.
A message
CAL FWD METER TO 100 WATTS
will display and both meter needles will bounce.
Use a small flat blade screwdriver and adjust the FWD trimpot R75, located behind the display, to set
the forward needle to the 100-watt mark.
5.
Press the [TUNE] button to calibrate the reflected needle.
6.
A message
CAL REF METER TO 20 WATTS
will display. Adjust the REF trimpot R76, located
behind the display, to set the reflected needle to the 20-watt mark.
7.
Press the [TUNE] button to end calibration.
8.
Turn off the tuner power and secure the cover back onto the tuner.
SWR Bridge Calibration
To calibrate the SWR Bridge, you will need a transmitter capable of 100 watts output, a precise calibrated
wattmeter, a 50-ohm dummy load, three 50-ohm SO-239 coax cables, a Phillips screwdriver, and a tuning
tool or small flat blade screwdriver.
WARNING:
Do not touch anything inside the tuner during operation! Serious, painful RF
burns can result.
WARNING:
Never operate the MFJ-993B with its cover removed; dangerous voltages and
currents can be present during operation. Never exceed tuner specifications.
Note:
The trimmers involved in this calibration are located on the main circuit board in front of the
TRANSMITTER connector; do not confuse these with the SWR/wattmeter trimmers.
1.
Turn off the power to the tuner and the transmitter.
