MFJ-991B Automatic Antenna Tuner
SKU Part Number: MFJ-991B
150 Watt IntelliTuner Automatic Antenna Tuner.The MFJ-991 IntelliTuner let you rapidly tune antennas automatically: unbalanced or single-wire (or...
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£259.96 £216.63
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150 Watt IntelliTuner Automatic Antenna Tuner.

The MFJ-991 IntelliTuner let you rapidly tune antennas automatically: unbalanced or single-wire (or balanced, with an external balun). MFJ's exclusive InstantRecall<™>, IntelliTune<™> and AdaptiveSearch<™> algorithms give you fast automatic tuning with more than 1000 non-volatile memories.
The tuner includes a highly efficient switching L-network with wide matching capability, 1.8 to 30 MHz coverage, cross-needle power meters, a port for an accessory remote control, a radio interface port, and heavy-duty 16 amp/1000 volt relays. It is rated at 300 watts PEP SSB and 150 watts CW.

256 values of capacitance and 256 values of inductance are available. With the inductance switched between the input and output side, this provides a total of 131,072 L/C tuning combinations. The nominal tuning ranges are 0 to 3900 pF and 0 to 24 µH.

All MFJ IntelliTuners™ learn and remember. When you transmit, they automatically adjust for minimum SWR and remember the frequency and tuner settings, safely stored in non-volatile memory. The next time you operate on that frequency (or close to it), these tuner settings are instantly restored and you're ready to operate in milliseconds. The tuner can learn and remember more than a thousand frequencies and tuner settings.

When you key your transmitter, MFJ's InstantRecall™ checks its memory to see if you have operated that frequency before. If so, tuning is instantaneous and you're ready to operate. If not, MFJ's IntelliTune™ algorithm (based on MFJ's famous SWR Analyzer technology) kicks in. It measures the complex impedance of your antenna. Next, it calculates the components it needs and instantly snaps them in.

Finally, it fine-tunes to minimize SWR, and you're ready to operate all in a fraction of a second. If the antenna impedance is not within the tuner's measurement range, MFJ's AdaptiveSearch™ algorithm goes into action. Frequency is measured and relevant component values are determined. Only those values are searched for fast tuning. If it still cannot find a match, the search is performed again using a different search pattern.

The target SWR can be set at 1.5 or 2.0. The minimum power to tune is approximately five watts. You can manually tune where you can't transmit (for listening out of ham bands). The optional MFJ-993RC Remote Control provides most tuner controls, allowing convenient remote locating of the tuner itself.

All of MFJ's IntelliTuners™ support radio tuner interfaces that are compatible with Icom AH-3 and AH-4 tuners and the Alinco EDX-2 tuner. Optional interface cables MFJ-5124A (for Alinco) and MFJ-5124I (for Icom) are available from MFJ Enterprises, Inc. Interface cables for compatible Kenwood and Yaesu radios will be available in the future.

The tuners enter a "sleep" mode when idle and when no transmit signal is present, turning off the microprocessor clock to avoid the generation of spurious signals.

Automatically matches antennas from 6 to 3200 ohms impedance
Handles 150 watts PEP SSB/100 watts CW
Tune in less than 15 seconds, usually less than 5 seconds
Over 1000 non-volatile memories for tuner settings
Highly efficient switching L-network matching circuit
1.8 to 30 MHz continuous frequency coverage
Selectable target SWR 1.5 or 2.0
Selectable SWR threshold 0.5, 1.0 or 1.5
Lighted cross-needle SWR/wattmeter with high, low and auto range options
Built-in frequency counter
SO-239 coax fed antenna connector
Connector for random wire or single wire antennas
Optional remote control
Optional radio interface for compatible radios
Impedance matching range: 6 to 3200 ohms
Minimum power for tuning: 5 watts
Maximum power while tuning: 100 watts with foldback, 20 watts without foldback
RF power limit: 150 watts PEP SSB/100 watts CW
Frequency range: 1.8 to 30 MHz continuous coverage
Frequency counter accuracy: ±1 kHz across HF bands
Frequency counter range: up to 50 MHz
Capacitance range: 0 to 3900 pF (256 values)
Inductance range: 0 to 24 µH (256 values)
Relay rating: 16 amp 1000 volts
Relay electrical life: 100,000 operations
Relay mechanical life: 10 million operations
Memory endurance: 1 million write cycles
Memory data retention: 100 years
Power requirements: 12 - 15 volts DC, 2.1 × 5.5 mm coaxial plug, center pin positive
Current consumption: 1 amp or less
Dimensions (approx.): 10.1 × 2.8 × 9.2 in. (257 × 71 × 234 mm) (width/height/depth) not including connectors
Weight (approx.): 3.7 lb (1.68 kg)


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