MFJ-998 Legal Limit IntelliTuner Automatic Antenna Tuner
Instruction Manual
©
2007-2010 MFJ Enterprises, Inc.
13
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 rear terminals are not accessible during operation. The single
wire connection may have high voltage while transmitting.
●
Disconnect all antennas from the tuner during lightning storms.
●
Always tune with low power (approximately 10-30 watts), and any in-line amplifier must be
bypassed. Apply maximum power only after tuning up.
●
Never exceed tuner specifications.
1. Place the tuner in a convenient location at the operating position. When using a random wire antenna
the feed through insulator may have high RF voltages. These voltages can cause serious RF burns if
the terminal is touched when transmitting.
Be sure to locate the tuner so this terminal cannot
accidentally be contacted during operation.
2. Connect the tuner to the transceiver or amplifier with 50-ohm coaxial cables capable of handling the
RF power levels expected. See Figure 1 on page 5.
3. Connect the antenna(s) to the tuner as follows:
•
Coaxial feedlines (RG-8/U or better) to the SO-239 connectors labeled ANTENNA 1 and/or
ANTENNA 2.
•
Random wire to the WIRE binding post on the back of the tuner. Note the back panel warning:
Do not connect WIRE and ANTENNA 1 at same time!
When a single wire antenna is
connected it “becomes” ANTENNA 1.
Note: Route all random wire antennas safely to prevent a RF burn hazard.
•
For balanced feedlines, connect an MFJ-912 1.5 kW 4:1 balun to the appropriate antenna
connector output of the MFJ-998.
4. A GROUND post is provided for an RF ground connection. See “Grounding Hints” on page 24.
5. Connect a 12 to 15 VDC power source capable of 1.4 amps to the input jack labeled POWER.
SWR/Wattmeter
The backlit cross-needle analog meter measures forward power,
reflected power, and SWR, and operates whenever the tuner is
powered on. Forward power up to 300 watts is displayed on the
left-hand FORWARD meter scale. Reflected power up to 60
watts is read on the right-hand REFLECTED meter scale. For
high-power tuning, meter ranges of 3000 watts forward and 600
watts reflected are available. Multiply the readings on these
scales by ten when in the high power meter range.
The meter can be set to low, high, or auto range (default). Auto range automatically sets the meter scales
according to the input RF power to the tuner. Forward power greater than 300 watts or reflected power
Figure 12. SWR/Wattmeter.
