End Fed Half Wave Antennas - Elgin Amateur Radio Society The Nelson antenna 9 to 1 unun did the trick. Power handling is 100 watts CW / SSB & 25W Data modes. So, if you connect a length of wire that presents an impedance of about 450 to the input, you'll get an impedance of about 50 on the output. SWR will vary based on topography, wire orientation and use of ground or counterpoise. For best results, use the Wire Length Feet 1.8 MHz 3.7 MHz 5.3 MHz 7.1 MHz 10.1 MHz 14.2 MHz 18.1 MHz 21.2 MHz 24.9 MHz 28.5 MHz 50.1 MHz EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 Twist the short and long wires together starting at an end of each wire. plan to use. stream shown in the column e. var sc_project=8077274; >> <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> So a 49:1 impedance transformer is needed to match the 50 ohms of the coax at the feed line. To DB's point of a single band antenna, this 49:1 transformer is a good choice for a single band matcher. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. End Fed Half Wave 40-10 Wire Antenna - N6DOZ (Also note that here may be instances where the suggested lengths may not work exactly due tothe many variablesin the surroundings of the antenna, wire length variances,your tuner, it's height above ground, it's construction,etc. google_ad_width = 160; Picture Information. He used 300 ohm twin-lead and a 4:1 UNUN, with a 1:1 current choke between the UNUN and the coax to the tuner and transceiver: The full-size "flimsy" (ref. Superglue 2 toroids together. The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. While these lengths have been shown to work well on many bands, which (Note: I am not satisfied with this part of the project, so I will describe it here briefly. The second smallest number I measured was 2.7pF, derived from the self resonance at 2.72 MHz with the magnetizing inductance (measured at 25.8 H) with the secondary open and the output wire folded to a small 1/2 length. 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 50 (unbalanced) coaxial input, hence UnUn. << Antenna Design Feeling a bit too lazy to calculate that by hand, however, I wrote a The counterpoise wire does not have to be similar in length to the main radiator wire and just a short wire is all that is needed, about 0.05 . Wire lengths for the 4:1 ratio in models 4932 and 4935. Windings are inserted into Teflon tubes increasingtotal breakdown to 10,000 volts. Typically unbalanced = 50/75 ohms too unbalanced = 450/675 ohms. This project assembles a 49:1 ferrite-core ("FT") type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. random wire page. 49:1 UNUN Transformer 2 Kw 160 - 40 m - Wire Antennas /Contents 5 0 R (Also check out AB3AP'Swebsite and say thanks for sharing his skills. Super Bullet Features: - Uses proprietary broadband impedance transformer design for maximum bandwidth with SWR < 2 from 1.8-61 MHz for 1500 Watt model and 1.8-30 MHz for 3000 watt model I will also find some sort of heat resistant packing material to help hold the transformer in place. 9:1 UNUN - MyAntennas.com 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 . When used with the stated lengths shown in thetable below, the 9:1 ratio will Based on the success of our model 4932, this 5kWconfigurationisalso perfect for matching both long and short length wire antennas for multiband use. Beginning from the 3rd band from the left, the vertical blue lines are: 160M, 80M, 60M, 40M, 30M, 20M, 17M, 15M, 12M, (11M), and 10M bands. all US ham bands. I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. nelson_antennas | eBay Stores Longer wire is always more Start winding the toroid with the twisted wires at loop #1 (see schematic below). Well then you need to choose a wire length that is at least 1/4 on 40 meters, and doesn't fall on any of the 1/2 multiples for ALL the bands between 40 to 10 meters While you could certainly calculate the lengths to avoid using the standard formulas, and then make a chart, the section below may be what you are looking for. <> /CropBox [0 0 748 752] Picture 1 of 9. 3. , This is a partial reprint (with permission) of an excellent series of articles published by KV5R The magic lengths to use with the End Fed longwire is 29, 35.5, 41, 58, 71 and 84 feet I use a 29 foot wire with my PackTenna 9:1 balun for 40m-10m and then add a 28 foot length for better coverage on 80m when needed. InJack's own words. Technical specification : Type : 49:1 Unun Frequency : 1.81 MHz - 30MHz Impedance ratio: 1:49 Input Impedance: 50 Output Impedance: 2500 Power Handling (CW/SSB) : 250W Core Type : 1x FT240-43 by Fair-rite Co. Capacitor 100pF 3KV Assembled and tested. Cannon". Enclosure Depth: 1.250 in. q EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! << This calculates to 4.2 m or 14 ft for an 80m end-fed. << Then verify it with your installed antenna and SWR measurements. Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands. The unun was floating at about 15 feet above ground. Cut the center conductor wire (free untwisted end of short wire) of the unun to the correct size, scrape the enamel insulation off of the free end with a box cutter, and solder it to the SO239 connector. He had heard good things about 'Balun Designs' so he recommended you. endstream endobj startxref I used a homemade jig made of an SO239 chassis mount to bare wires, alligator clips, and a coax-jumper with PL259 (UHF male) ends; see picture below. which got me thinking. Wire lengths for the 4:1 ratio in models 4130, 4132, 4134, 4932 and 4935. IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. Generally an EFHW will be in the range of 2,000 to 5,000 ohms at the very end of the dipole when resonant. The length of enamelled copper wire per winding for the T-200-2 powdered iron toroid core is determined by length per winding = 50mm per turn plus 250mm tails. However, the radio didn't tune up very well on 15 meters. Building on the original 1:1 design by Dr. Jerry Sevick, this balun has two (2) cores in a stacked Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW, Decrease Quantity of Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW, Increase Quantity of Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW. I wrote a small C program that does just what Jack did, butI used the band edges. The short piece is for the primary winding of the transformer, and the long piece is for the secondary winding of the transformer. The 30 day return period lapsed before I could get the antenna deployed to test it. 10C) for the 10-80 m bands, or even 6-160 m: 17 ft (5.2 m) of twin-lead and 68 ft (20.7 m) of antenna wire (i.e., standard dimensions). >> How We Flew An End-Fed Half Wave (EFHW) Ham Radio Antenna On A - KM1NDY >> Kj8~q7c? //-->, The "Best" Random Wire Antenna Lengths End Fed Half Wave Antenna Coupler Schematic - 7-30MHz. high the other 1.5m (4.5feet). HF Antenna Choice 9:1 vs 49:1 vs PAR - Antennas - SOTA Reflector wire is at least 1/4 wavelength. Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth. Some of these numbers are too close to squeeze in between them. . Product Reviews At multiples of half wavelengths of the https://www.kb6nu.com/playing-end-fed-wire-antennas-91-ununs/, http://www.hamuniverse.com/randomwireantennalengths.html, https://www.youtube.com/watch?v=sty7RlXQoJI, https://www.youtube.com/watch?v=WwJnXTVUrgI, Quote from: refmo on October 15, 2019, 2036 UTC, Quote from: joczo on October 16, 2019, 0815 UTC, http://www.w3pga.org/Antenna%20Books/Reflections%20III.pdf, http://www.arrl.org/files/file/Technology/tis/info/pdf/7007024.pdf, http://www.tasrt.ca/AntennaTips/AntennaTips.htm, http://www.wb2rcb.com/documents/balunlin.pdf. The 49:1 unun with 3000 ohms of resistance shows a VSWR under 10:1 from 160M to 15M, and less than 3:1 from 80M to 20M. %%EOF . Turns 1 & 2 are primary windings (the short wire). Yes, with the recent surge in popularity of the end-fed half-wave antenna, the 49:1 balun has also become the defacto ratio for use with them. 3 0 obj This design is excellent for matching both long and short length wire antennas for multiband use. frequencies for your country or favorite modes. I have found this calculation to work well, however it depends on many factors such as wire used, location etc. So for 80 meters (say 3.525 MHz) this gives you about 133' of wire. Clansman End Fed Long Wire Antenna Used. Re: 49:1 transformer for EFHW antenna - groups.io u?X`f0&/Ri;W0Tn_*TX:ug Mike ab3ap, Editors note: Many thanks to Jack, VE3EDD (SK)and Mike, AB3APfor sharing their math and computerskills with us. /Height 752 hb```YloD@(aKI V!}g@~}%Q/[[~_=Wy-:O)x[~hs/~SGeG _QE C6q %r Anyway, an old friend mentioned 'MyAntenna.com' but they were closed for the summer. A way of connecting the analyzer to the transformer. UJM-49-1 $56.99 Save up to 6% when you buy more. Well, I didn't think it would make any difference at that many multiples. They just saved you and I loads of time and frustration. Jack, VE3EED, used center frequencies of thebands described in the article above, and I thought it would be nice to use band edges. Again, the bands are USA, so change them What Is an End-Fed Half-Wave (EFHW) Antenna? - OnAllBands 9 0 obj Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. This is the latest and greatest transformer design for End Fed Half Wave (EFHW) antennas. 0 To summarise the results WRT to reference antenna consisting of 30ft wire vertical fed with auto- 1936 article, however, fall in line with 468/f and so is used here. % Multiples are on C and
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