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This project assembles a 49:1 ferrite-core (“FT”) type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. It is optimized for 3.5/7/10/14 MHz but will work reasonably well on all amateur bands from 80 meters thru 10 meters with a 135 foot length of wire and a short connection to ground.
ratio (49:1, 56:1, 75:1 and 81:1) UNUN (UN-balanced to UN-balanced) transformers and antennas. The efficiency- Insertion loss of the transformers continues to be unmatched by any copycat or competitor products on the market.
I typically tune the antenna initially with the remaining spool of wire still attached to the end, unfurling what I need. Drill or poke a small hole (preferred) in the plastic tubing to feed the wire through to secure the ends of the coil, or cut slots as shown above.
Download The Mini 49:1 UNUN Instruction manual here. Antenna wire lenghts. The End Fed Half Wave antenna requires to cut one of halfwave lenghts.
An 80-10 end-fed half-wave antenna can be a very good performing part of an HF station. But its performance depends heavily on a well-designed and carefully constructed 49:1 unun, which matches the long wire impedance to within tuning range of operation. But the perfor-mance of an end-fed antenna is also very dependent on height above ground.
With a 49:1 or 64:1 UNUN, no tuning is required and no antenna tuner is required (or perhaps a “touch up” tuner with up to 3:1 VSWR capability that many modern rigs have built-in.)
27 mar 2024 · Since we have not seen a good, rigorous measurement of any 49:1 UnUn embedded in a 50-ohm system, I constructed a couple to accomplish that measurement by connecting them in series: 50-ohms to 2.7 kΩ and back to 50-ohms.
