MFJ-998RT Legal Limit IntelliTuner
TM
Automatic Remote Antenna Tuner Instruction Manual
© 2011 MFJ Enterprises, Inc
MFJ-998RT Version 1A
4
Installation
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 antenna terminals are not accessible during operation. The single wire
connection will have high voltage while transmitting.
•
Do not mount in a position that will put it under water at any time.
•
Do not mount it in a place that will allow sprinklers or water hoses to spray the weather seals or
connectors
•
Always tune with low power (about 10 watts). Apply maximum power only after tuning up.
•
Never exceed tuner specifications.
•
Do not transmit with a high SWR for extended periods of time.
1. Mount the tuner in a convenient place to the antenna. Mount it in such a way that it will not
come in contact with people, pets, or shrubbery. The Wire terminal will have high RF voltages
on it in use. These voltages can cause serious RF burns if the terminals are touched when
transmitting.
2. The tuner can be mounted vertical or with the plastic cover up. Do not mount with the cover
face down. Water may accumulate and seep into the tuner. If mounted with the connectors
toward the bottom then take the cover off and place it with the MFJ logo upright so any water
that may get into the tuner will have a chance of draining out at the bottom of the cover.
3. Connect the tuner to the transceiver, the amplifier, and the antenna with 50-ohm coaxial
cables capable of handling the RF power levels expected. See Figure 1 on page 4. 3.
Connect the antenna(s) to the tuner as follows:
4. Random wire or single wire line antennas should be connected to the WIRE binding post on
the back of the tuner. Note the back panel warning: Do not connect WIRE and ANTENNA at
same time! Both are connected in parallel.
Note: Route all single and random wire antennas safely to prevent RF burn hazard. For balanced
feedlines, connect an MFJ-912 1.5 kW 4:1 balun to the antenna connector output of the MFJ-998RT.
5. Several GROUND posts are provided for RF ground connections. See “Grounding Hints” on
page 24.
6. Connect up the feed line between the transceiver or amplifier and the tuner to the
TRANSMITTER connector on the tuner. The cable should be 50 ohm and heavy enough to
handle the power of your radio or amplifier.
7. If optional Lightning Surge Suppressors are used in line with the feed line to the tuner make
sure they are the type that will pass DC such as the MFJ-272. DC power is supplied down the
feed line to the tuner.
8. The feed line from the tuner is connected to the MFJ-4117 BIAS TEE RF/DC connector.
9. Connect the MFJ-4117 BIAS TEE RF connector to the transceiver or amplifier if used.
10. Connect a 12-15V power supply to the DC input of the MFJ-4117 BIAS TEE to supply power
to the tuner. The station supply or an MFJ-1316 will work. The supply needs to be capable of
supplying 1.4A.
11. If an optional local antenna switch is used place it before the BIAS TEE (the RF side not the
RF/DC side) to prevent the chance of shorting out the DC line with the switch.
Note: The MFJ-998RT is not designed to work with remote antenna switches. Some antennas and
antenna switches have DC continuity between the center pin and shield which will short out the power
supply when switched to those positions
