MFJ 1899T antenna tripod mount and balun

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Summary

This little box serves two purposes; to make a sturdy tripod mount for my MFJ 1899T multiband vertical antenna, and to improve its performance by adding a 1:1 current balun and a banana jack for adding counterpoises. The balun will make sure the performance isn't affected by the length of the antenna cable. It was built to be used in a lightweight QRP radio setup based on a Yaesu FT-817ND.

Parts

  • Small metal chassis (approx 50*50*25mm)
  • BNC-connector and four M3 screws
  • Female SMA-connector
  • FT114-43 ferrite core
  • 0.5m RG-174 coaxial cable
  • Female banana connector
  • Zip-ties and heat shrink tubing

Construction

I started by winding ten turns of RG-174 on the ferrite core.

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I then drilled and threaded (M3) three of the mounting holes for the BNC-connector. The remaining hole was not threaded, as I needed a nut on the inside of the box anyway.

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The coaxial cable was then soldered to the BNC-connector, and the ferrite core was glued to the inside of the box.

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This step includes threading (1/4"-20) the underside of the box for mounting on a tripod, and terminating the cable with a female SMA-connector. I made a neat cable of approx. 5 m length for my Yaesu FT-817ND as well. It is terminated with a BNC- (for the front panel connector) and an SMA-connector.

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Design: Jon Petter Skagmo