MFJ -1778 G5RV User Manual

MFJ -1778 G5RV User Manual

Multiband antenna

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Summary of Contents for MFJ MFJ-1778 G5RV

  • Page 2: Table Of Contents

    MFJ-1778 G5RV Multiband Antenna Table of Contents Introduction ........................1 Theory Of Operation ....................... 1 80 meter band:..................... 1 40 meter band:..................... 1 30 meter band:..................... 2 20 meter band:..................... 2 17 meter band:..................... 2 15 meter band:..................... 2 12 meter band:..................... 2 10 meter band:.....................
  • Page 4: Introduction

    3/2 wavelength center fed antenna for 14 MHz, but amateurs soon discovered it would offer reasonable performance on many other bands. The MFJ-1778 (G5RV) consists of a 102 foot flat top fed with a 32.5 foot 450 ohm matching section ending in an SO-239 coaxial connector.
  • Page 5: Meter Band

    MFJ-1778 G5RV Multiband Antenna 30 meter band: On 30 meters the MFJ-1778 (G5RV) functions as an extended double zepp. The current distribution of the antenna and matching line is shown in figure 3. The horizontal radiation pattern is similar to the pattern of the 40 meter band (broadside) Figure 3 but has four additional minor lobes.
  • Page 6: 160 Meter Band

    MFJ-1778 G5RV Multiband Antenna 160 meter band: The MFJ-1778 (G5RV) can function as a top loaded vertical antenna with the dipole element acting as a capacitance hat on 160 meters. Operation on this band requires a ground screen or radial ground system (see the INSTALLING and OPERATING THE ANTENNA section).
  • Page 7: Installing The Antenna

    MFJ-1778 G5RV Multiband Antenna Installing The Antenna Please read the following suggestions and examples. The best location for this antenna is as high and far away as possible from utility wires, other antennas, and other structures. It is difficult to find a perfect location, so the best compromise usually must be accepted.
  • Page 8: Sloper Antenna

    Never attempt to operate this antenna as a conventional dipole on 160 meters! To use the MFJ-1778 as a Marconi antenna, the bottom end of the feeder (ladder line) and any vertical coax should be connected together at ground level. This allows the vertical feedline to become a radiating element.
  • Page 9: Balun Requirement

    MFJ-1778 G5RV Multiband Antenna conductive than dirt, copper is several hundred times (millions of milliohms/meter) better than saltwater. Copper radials obviously offer a much better ground than saltwater. Ground rods almost never suffice for RF grounding in applications like this because they connect to the lossy dirt.
  • Page 10: Tuning The Antenna

    Tuning The Antenna The G5RV requires a tuner to match it to the transmitter impedance. Operating this antenna without a tuner is not recommended. The use of a tuner like the MFJ-962C or MFJ-986 will provide proper matching on all HF bands.
  • Page 11: Technical Assistance

    You can also send questions by mail to MFJ Enterprises, INC., P.O. Box 494, Mississippi State, MS 39762; by FAX to 601-323-6551; through Compuserve at 76206,1763; or by email to 76206.1763@Compuserve.com.

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