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Here’s a nice homebrew project that would also suit constructors wanting to build a 9:1 Un-un [Unbalanced to Unbalanced] transformer. The heart of the Un-un uses a Type 43 [FT240-43] core and consists of a trifilar [3 wire] winding arrangement around the core.
Requiring a unun to feed a long wire antenna ideally without a tuner a 9:1 voltage unun design using a T200-2 Toroid core was selected. Figure 1 Typical 9:1 voltage unun and long wire antenna configuration.
12 lut 2009 · Mam pytanie jako świeży adept pracy na KF przyszedł mi do głowy pewien pomysł. Otóż posiadam aktualnie dipola na pasmo 80 m - 2x19,5 m z balunem 1:1. Czy jeśli wykonał bym balun 9:1 coś takiego jak na stronie http://www.m0ukd.com/Magnetic_Long_Wire_UnUn/index.php to czy po podpięciu 19,5 m z jednego ramienia stroiło by mi sie to na ...
With the 9:1 voltage unun and wire lengths suggested in the below tables the antenna should present non extreme impedances for all HF amateur band frequencies. This page is far from complete and represents the ongoing investigation into this type of antenna.
If you want to make one, look at Peter's video on TRX Bench on YouTube. Part 4 is about the 9:1 UnUn, but do yourself a favour, look at every one from the begining.. This is the choke and UnUn to go for.
Direction: Fold the 3 metres of copper insulated wire in two. Mark the wires’ end so to recognize them when the windings is done. Wind 13 to 19 turns of the bifilar wire ( more turns better response to lower band ). Connects the wire to the box terminal and the UHF connector ( SO 239 ) see the pics. READY.
These are sometimes known as a Magnetic Longwire Balun. Its really an impedance transformer (9:1) to feed a high impedance, end fed (unbalanced) random wire which is likely to be a few hundred ohms, and transform it into something closer to a 50Ω (unbalanced) coaxial input, hence UnUn.
