MFJ 1789 Instruction Manual
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MFJ 1789 Instruction Manual

9 band rotatable mini dipole
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Summary of Contents for MFJ 1789

  • Page 2 A 6'-8' rigid mast or other mounting pipe between 1" and 1.5" outside diameter. (suitable materials • include TV mast sections, galvanized iron pipe, or heavy duty rigid conduit.) Quality low-loss 50-Ohm coax with a PL-259 from antenna to transmitter. • • An Antenna Analyzer (MFJ-259B or similar), or SWR meter and transceiver...

  • Page 3: Specifications

    If necessary, it can even be mounted inside an attic! The MFJ-1789 is inconspicuous and low profile -- not much bigger than a TV antenna, and can easily be turned by a lightweight TV rotator such as the Hy-Gain AR-35.

  • Page 4: Choosing A Location For The Antenna

    1-1/2" OD. The use of soft or thin wall masts is not recommended Portable Operation The MFJ-1789 may be disassembled as necessary for transporting to a temporary location. Ideally, just remove the two HF loading coil assemblies leaving the two main elements and 2- & 6-meter stub assemblies intact.

  • Page 5: Tools And Time Required For Assembly

    MFJ-1789 Rotatable Mini-Dipole Instruction Manual TOOLS AND TIME REQUIRED FOR ASSEMBLY The estimated assembly time is two hours. Antenna assembly requires the following hand tools #2 Phillips screwdriver • 5/16" nut driver for #6 nuts and hose clamps. • Small (4”-6”) adjustable wrench OR •...
  • Page 6 MFJ-1789 Rotatable Mini-Dipole Instruction Manual The 6- and 2-meter stubs are not required if you have no interest in operating on these bands. HF band operation will not be affected if the 6- and 2-meter stubs are not present. After the antenna is assembled and adjusted for resonant frequency and SWR, it can then be mounted on a tower or rooftop and given final adjustments.
  • Page 7 MFJ-1789 Rotatable Mini-Dipole Instruction Manual Note: When the balun is mounted as shown, the mast size is limited to 1-3/8” diameter maximum. For a 1-1/2” diameter mast, you must mount the balun directly on the mast below the fiberglass rod with the additional U-bolt set provided.
  • Page 8 MFJ-1789 Rotatable Mini-Dipole Instruction Manual 9) Using six hose clamps (three on each radiator), clamp the fiberglass insulators so as to support the 16” and 55” threaded rods. Position the insulators as shown in Figure 4. 10) Mount the four stubs (two on each side) by threading a 10-32 x 3/8" nut 1/2" near the end of the threads.
  • Page 9 MFJ-1789 Rotatable Mini-Dipole Instruction Manual Aluminum Jumper Aluminum Radiator 13) Install the aluminum tab onto the screw at the bottom of the 10 meter loading coil where the aluminum jumper is also connected. Loosen the mounting nut for the jumper and install one end of the tab onto the screw and reinstall the nut.

  • Page 10: Tuning The Antenna

    An SWR analyzer such as the MFJ-259B or equivalent is highly recommended when tuning the MFJ- 1789. While a transceiver and SWR meter can be used, an SWR analyzer will significantly decrease the time and effort necessary to tune the antenna.
  • Page 11 MFJ-1789 Rotatable Mini-Dipole Instruction Manual WARNING: You will be trimming the outer ends of the spokes. The sharp sends can cause a hazard until they are covered with the plastic caps. Therefore it is VERY IMPORTANT to wear safety glasses when trimming the spokes, or when working near the antenna.

  • Page 12: Grounding Considerations

    MFJ-1789 Rotatable Mini-Dipole Instruction Manual low as 130 MHz to be covered with the stub fully extended and 148 MHz with the stub fully contracted. NOTE: The 2-meter resonance is affected by other resonances in the overall antenna structure. You may find a fixed resonance close to the 2-meter band that has a very low SWR, but the resonant frequency of this resonance will not be adjustable.

  • Page 13: Technical Assistance

    MFJ Technical Service at 662-323-0549 or the MFJ Factory at 662-323-5869. You will be best helped if you have your unit, manual and all information on your station handy so you can answer any questions the technicians may ask.
  • Page 14 MFJ-1789 Rotatable Mini-Dipole Instruction Manual NOTES...

  • 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 ENTERPRISES, INC. MFJ-1789 Manual 300 Industrial Park Road Version 1B Starkville, MS 39759 Printed In U.S.A.

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