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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.
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.
Attach a 2400 ohm resistor between the antenna wire and ground, and test using a SWR meter. SWR should be under 1.5:1. Alternatively, set up a half-wavelength wire outside and connect the matching unit with an antenna analyzer.
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.
High Impedance UNUN for EHFW antenna The UNUN has a high impedance ratio (49:1 to 64:1) – not feasible to use transmission line transformers whose practical limit is about 16:1. It is a conventional transformer. Uses a ferrite toroidal core or cores (usually Type 43 or type 52 material). Most 1:4 and 1:9
22 lut 2021 · The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. You will also need a half-wavelength length of wire (14 or 12 gauge typically) in order to construct an antenna radiator for whichever ham band you choose.
