nelson_antennas | eBay Stores I made just a touch over 100 QSOs today with the new unit. Vhf and Up Start winding the toroid with the twisted wires at loop #1 (see schematic below). This is not exactly a 1/2 wavelength in free space, but works for wire as it has a different velocity factor than "air". The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. Wait a few minutes for glue to set. multiples, and of course different band combinations yield different 4 0 obj The 30 day return period lapsed before I could get the antenna deployed to test it. 74 0 obj <>stream Best SWR was . A 49:1 would match 50 ohms to about 2,450 ohms and a 64:1 matches to 3,200 ohms, typical of a 1/2 wave end fed. . /Im0 Do AndWhat Is It Used For In Antennas? This was 9m vertically metres up a fishing pole and then about 5.8m out. Home-brew End-Fed 49:1 UnUn. - KA9QJG Repeaters 49:1 or other high ratio transformers are for resonant "cut to frequency" antennas like the traditional zepp/fuchs antenna. The major point of this message is to tell you that approximately 20 minutes after I connected the balun unit to the antenna, I made contact with a gentleman in Italy-my first European contact!! Balun Designs. However, the radio didn't tune up very well on 15 meters. 4 x 4 x 2 electrical junction box (available at big box hardware stores), One PVC DWV Test Cap (available at big box hardware stores in plumbing). Engineering the EFHW 49:1 Transformer and Antenna An UNUN is needed to match the high impedance of an end fed antenna (2k-4k ohms range). PDF 33ft Verticals and 4:1 Ununs - G8JNJ The goal of the impedance transformer is match the 50 ohm impedance of the feedline (coaxial cable) with the potential 3000 to 4000 ohm impedance expected from an end-fed half wave antenna wire radiator. Here are the final numbers (in my opinion) in green below that would be good for a long-wire antenna: (You may want to make a note of them), REVISED: 29 35.5 41 58 71 84 107 119 148 203 347 407 423, REVISION NOTE: We had a note from James, KB5YN, pointing out that one of my so-called GOOD numbers was 220 feet. installed, it is a compromise antenna but great for portable use because 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. Bullet 50:450 (9:1) HF Unun, 1.8-61 MHz, 1500/3000 Watts, End Fed Long Experimenting by slightly changing the wire length (+ or-) is encouraged to provide best overall performance. (Note: I am not satisfied with this part of the project, so I will describe it here briefly. /MediaBox [0 0 748 752] Connect this ring terminal to one of the SO239 chassis bolts. That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . <>>> 2 0 obj The 49:1 impedance transformer will help you bring down the high impedance of your resonant EFHW antenna to almost 50 Ohm. END FED "RANDOM WIRE" HF DIPOLE 9:1 ANTENNA RELACEMENT ELEMENT ONLY $28.99 Save up to 6% when you buy more. var sc_security="1df091cc". $119.95. 1863 1.49 swr 3915 2.50 7200 1.80 14.332 1.29 18.130 1.07 21.300 1.40 24.950 1.30 28.400 1.37 This is a great antenna that is .
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