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Summary of Contents for MFJ MFJ-976
- Page 1 1500 Watt Fully-Balanced Antenna Tuner Model MFJ-976 INSTRUCTION MANUAL CAUTION: Read All Instructions Before Operating Equipment MFJ ENTERPRISES, INC. 300 Industrial Park Road Starkville, MS 39759 USA Tel: 662-323-5869 Fax: 662-323-6551 COPYRIGHT 2006 MFJ ENTERPRISES, INC. VERSION 1B...
- Page 2 30 MHz, continuous. It is rated at 1500 watts PEP SSB and CW. The MFJ-976 is designed to match 50 ohm output transmitters or transceivers to virtually any antenna. Peak and average forward power, reflected power, and SWR are displayed on the MFJ-976's illuminated cross-needle meter.
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Page 3: Peak Reading Swr/Wattmeter
The wattmeter has an internal lamp that backlights the meter scale. The lamp circuit requires power from an external 12 Vdc source, such as the optional MFJ-1312D power supply. The rear panel jack accepts a 2.1 mm coaxial plug with the center conductor positive (+) and the sleeve negative (-). The negative lead is grounded... -
Page 4: Installation
Two jumpers must be installed on the rear panel for operation. These jumpers are installed at the MFJ Factory. Figure 2 indicates the location of these jumpers with dashed lines on the right side of the rear panel. -
Page 5: Operation
Note: Always use the most capacitance (settings closest to 0) for the most power handling and the least loss. Use the smallest possible inductance (the lowest number possible) also. Note: The MFJ Air Core™ Roller Inductor is designed with an exclusive Self-Resonance Killer™ that keeps potentially damaging self-resonances away from your operating frequency. This feature is switched in and out of the circuit with a built-in switch in the roller. -
Page 6: Adjustment Procedure
MFJ-976 Legal Limit Fully Balanced Antenna Tuner Instruction Manual Adjustment Procedure 1. If the exciter or transmitter must be tuned, do it into a 50-ohm dummy load. 2. Set the ANTENNA, INDUCTANCE, and TRANSMITTER controls at the settings in the Suggested Tuning Chart on Page 9. -
Page 7: In Case Of Difficulty
For operator safety a good outside earth ground or water pipe ground should always be installed and connected to the case of the MFJ-976. Make certain the safety ground also connects to the transmitter and other station accessories. A wing nut post marked GROUND is provided for ground connections. -
Page 8: Antenna System Hints
MFJ-976 Legal Limit Fully Balanced Antenna Tuner Instruction Manual Antenna System Hints Location For the best performance, an end-fed long wire antenna should be at least one quarter-wavelength long at the operating frequency. Horizontal center-fed antennas should be at least a half-wavelength long and located as high and clear as possible. - Page 9 40-Meter antenna is to load either or both feedline wires (in parallel) as a longwire. The antenna will act like a “T” antenna worked against station ground. SWR Meter Calibration The MFJ-976 has been calibrated at the factory. If it should ever need to be recalibrated, then follow this procedure: Equipment Needed 1.
- Page 10 MFJ-976 Legal Limit Fully Balanced Antenna Tuner Instruction Manual 8. With the 3000/300 Watts button pushed in for the 600 Watt reflected scale, Transmit 100 Watts as indicated on the reference meter. Adjust the HI REF trim pot to set the reflected power scale to 100 Watts.
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Page 11: Technical Assistance
You can also send questions by mail to MFJ Enterprises, INC., 300 Industrial Park Road, Starkville, MS 39759; by Facsimile (FAX) to 662-323-6551; or by email to techinfo@mfjenterprises.com. - Page 12 MFJ-976 Legal Limit Fully Balanced Antenna Tuner Instruction Manual Suggested Tuning Chart Frequency (MHz) Antenna Inductance Transmitter Load(Ω) 3.75 3.75 3.75 5.34 7.15 7.15 7.15 10.1 10.1 10.1 14.2 14.2 14.2 18.1 18.1 18.1 21.2 21.2 21.2 24.9 24.9 24.9 28.5...
- Page 13 MFJ-976 Legal Limit Fully Balanced Antenna Tuner Instruction Manual Logged Tuning Chart Use the chart below to log values for your station. You may want to copy this chart and post it by your tuner. Frequency (MHz) ANTENNA INDUCTOR TRANSMITTER...
- Page 14 MFJ-976 Legal Limit Fully Balanced Antenna Tuner Instruction Manual Schematic...
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Page 15: Full 12-Month Warranty
MFJ Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFJ Enterprises, Inc. and purchased from an authorized dealer or directly from MFJ Enterprises, Inc. to be free from defects in material and workmanship for a period of 12 months from date of purchase provided the following terms of this warranty are satisfied. - Page 16 MFJ-976 Manual 300 Industrial Park Road Version 1C Printed In U.S.A. Starkville, MS 39759...
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