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12 sie 2016 · A 9:1 unun is a transformer that reduces the impedance at the input by a factor of 9. So, if you connect a length of wire that presents an impedance of about 450 Ω to the input, you’ll get an impedance of about 50 Ω on the output.
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.
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.
This video discusses End Fed antennas and particularly End Fed Random Wire antennas for ham radio. Additionally, we go through the process of building a 9:1...
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.
I'm always fascinated by the "magic" 9/1 un-un for longwire antennas, also called "Magnetic Longwire Balun". You build this device, connect the transceiver and a longwire antenna of almost random wire, and GO!!!
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.
