9:1 Selectable Ground UN-UN for End-Fed Receive Antennas

This is a nice little project for those of you who wish to have a high performance, low noise receive antenna for the HF bands.
This transformer configuration is not a Balun, but rather an UN-UN as it takes a single UNbalanced end fed wire antenna and
couples it with an UNbalanced 50 ohm coaxial connector to feed a receiver.
This UN-UN, Works quite well with only 45' of 14 AWG stranded copper wire.  I prefer a white jacket on my antenna wire as
it helps the wire disappear against the sky.  It also keeps those nosey neighbors and the neighborhood ASSociation folks
from complaining as well!  However, I suppose bright fluorescent Pink or Green could work if you want to thumb your nose at
any of the aforementioned groups. :)

The unique part of this design is that you can choose the grounding to suit your location and antenna to result in the lowest noise.
I use mine with 90' of 14 AWG stranded copper wire.  This is my primary receiving antenna for my iCom R-75 and it hears VERY WELL!



SO-239 with plating filed so wire can easily be soldered for grounding.          A dab of flux to the location to be soldered helps greatly. (so does the vise)

The finished SO-239 with ground wire soldered.                                          Rat Shack project box 3" x 2" x 1" is plenty large enough for this fabrication.

Project box drilled for SO-239, connection bolts and hanger eyelet.               Trifilar wound toroid from schematic above.

Another view of toroid showing heat-shrink tubing insulating connections.         Installed, wired and hot-melt glued into the project box.

Sealed and labeled.  Note copper ground strap between both ground terminals.


Choose the toroid mix that suits your needs the best.  The one pictured above is from Micrometals, Inc.
I used T130-6, trifilar wound with 22 AWG Enameled Copper Wire.

I have built several of these for my friends.

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