other-antennas QRP-GUYS Tri-band loaded vertical antenna

Discussion in 'Antennas' started by DD5LP, Mar 21, 2018.

  1. DD5LP
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    DD5LP Crack-Boarder X-108 Member

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    I have just built this US$15 kit and am testing it out - in my version I have changed the turns on the toroids to be 44T on each toroid to make the antenna cover 20, 40 & 60m but the standard version covers 20, 30 & 40m.

    QRPGuys Portable Tri-Band Vertical Antenna - QRPGuys

    upload_2018-3-21_8-20-26.png

    73 Ed.
     
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  2. DD5LP
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    DD5LP Crack-Boarder X-108 Member

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    Unfortunately, I have something not so good to report on this antenna. It's resonant frequency changes dependant upon the length of feed coax and where it is installed! I at first thought that my changes to make it cover 60m had caused the problem, but them I rebuilt it in the standard configuration and the problem is still there. I can set up the antenna in the garden and have it resonant on 20, 30 & 40m and then set it up on a summit and the resonance is off and hence the SWR is 5 or 6 to 1! I had hoped that it was only the feed coax length that was causing the problem and so I soldered a set length of coax to the antenna board and used that in the garden and on the summit. Resonant in the garden, way off on the summit!

    It was suggested that I add a common mode choke in the feedline, which I did but that did not resolve the problem.

    If someone want an antenna to setup in one location and leave it, then this antenna will most likely work for you but for portable operation it is a NO NO.

    73 Ed.
     

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