MFJ-993B IntelliTuner Automatic Antenna Tuner
Instruction Manual
2005-2012 MFJ Enterprises, Inc.
3
Fast Start
WARNING
●
Never
operate the tuner with its cover removed. Contact with the components inside the
tuner while transmitting will result in painful RF burns.
●
Locate the tuner so that the rear terminals are
not accessible
during operation. The single
wire and balanced line connection may have high voltage while transmitting.
●
Disconnect
all antennas from the tuner during lightning storms.
●
Always
tune with low power (2 watts minimum, 10-20 watts recommended), and with any
in-line amplifier bypassed. Apply maximum power only after tuning up.
●
Never
exceed tuner specifications.
1.
Connect the MFJ-993B to a 12-15 VDC voltage source capable of supplying at least 1 amp.
2.
Connect your transmitter or amplifier output to the TRANSMITTER connector using a 50-ohm
coaxial cable.
3.
Connect your coax-fed antenna to the ANTENNA 1 connector using a 50-ohm coaxial cable, or
connect your random wire to the WIRE binding post, or connect your balanced line antenna to the
BALANCED LINE binding posts and connect a jumper between the other two posts as indicated.
4.
Connect your ground connection to the GROUND post.
5.
Press the [POWER] button to turn on the MFJ-993B tuner. The Power-On Reset default is also for
StickyTune
TM
to be ON. Place the [ANT] button in the out position to select antenna 1.
Note:
StickyTune
TM
after power cycle means that the MFJ-993B will do a full tune after a
power cycle on the first frequency you transmit on only. No other frequency or memory
solutions will be affected. So you can fully re-tune on any frequency by simply cycling
power
.
6.
Lock the [AUTO] button in to select semi-automatic mode.
Note:
The AUTO button should always be IN (semi-automatic) unless a compatible radio
interface cable is connected between the MFJ-993B and your transceiver. This ensures
that the MFJ-993B does not attempt tuning during high-power operation, and is
particularly important when an HF amplifier is in-line.
Note:
If an amplifier is in-line, it should always be bypassed prior to tuning.
7.
Key your transmitter to output a carrier of 2-20 watts CW, FM or AM.
Note:
Due to detector non-linearities at low power levels, best SWR tuning accuracy occurs at
10-20 watts.
8.
Press and hold the [TUNE] button for one second to start the automatic tuning process. When
completed, check to ensure an SWR of 1.5 or less has been achieved before increasing RF power.
Note:
If you have a tuning solution on one band or antenna and you then change bands or
antenna and attempt to transmit a tuning signal, the previous tuning solution may be
sufficiently severe such that no power is detected by the MFJ-993B (the MFJ-993B will
tell you to increase power). When this occurs, simply bypass the MFJ-993B and then
initiate a tune.
