http://udel.edu/~mm/ham/randomWire/. So for example 80m could range in length from 120 to 133 feet. 31 How We Flew An End-Fed Half Wave (EFHW) Ham Radio Antenna On A - KM1NDY 33 ft #18 insulated copper wire (20m half wave), Counterpoise: 1 meter coax (0.05 x wavelength) connected between 64131 and Balun Designs 1115d Isolation /Choking balun, If you would like to use high power up to legal limit with a single end fed wire antenna (not necessarily a half wave) consider using our. The Short Answer Would Be That an UnUn Is a UN balanced to UN balancedmatching transformer. JavaScript is disabled. (wlSR9dJ_x%+VHX4FRr 3>;g^x%g'wkJu,i~#Q"2|WGf[!_m]#&1$)R.{--" 'dGO;=_B$T}". Hopefully these random wire length calculations will help us all make this "easy" antenna work better! End Fed Half Wave Antenna Coupler Schematic - 7-30MHz. Each vertical blue line represents an amateur radio band. 9:1 Unun 1.5-54MHz 2kW 9132S. When do you use a 1:1, 9:1 or a 49:1 balun? The beauty of the halfwave antenna is it's a complete antenna in the sense it needs no counterpoise. You can add your own wire or get the complete product from this link EFLW-3K antennas. It may not display this or other websites correctly. June 8, 2022 at 9:17 am. recommended on VE3EED's page because I use all halfwave The fewer bands, the fewer high impedance regions to avoid. 1:64 vs 1:49 balun for an end fed?? : r/amateurradio - reddit K1S Valentines Are (Almost) Out The Door! | Notice from column f that there is no length giving low impendance for Our Ask An Elmer panel discuss this question - what's the difference between matching units?Please consider using. Enclosure Depth: 1.250 in. endobj Ham Radio End Fed Antenna with a 1:64 Matching Network That meant calculating all the way to 32 multiples of a half wave on 10 meters. Drill another hole in the same side as the antenna radiator wire mount hole. endobj End fed 9:1 58ft wire and 17ft counterpose wire touching ground. Privacy Policy shown in the column e. var sc_project=8077274; Start winding the Matching Auto Transformer, each pass through the center of the core equals one turn. endobj program or two to do all the dirty work. is helpful if you're in a hurry to get on the air, read up on the topic Cut a 4 foot length of AWG #18 enameled wire. About Hamuniverse IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. In total 29 contacts were made from British Columbia to Texas to Florida in 40 minutes on 20M. I usually go with a 3.2k transformation wire winding ratio of 8:1 which is a final impedance conversion of 64:1 (50ohm * 64 = 3.2k ohm). [ /PDF /Text /ImageI ] 9:1 UNUN - MyAntennas.com 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. The length of a half wave antenna is calculated using the following formula: L (ft) = 468 / f (freq in mhz). This antenna, which works on 10, 15, 20, and 40 meters, has a very high impedance of around 2,500 Ohms. EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 , Most matching problems occur when the antenna system Do what works best! Here Is a 250 Watt Home-Brew That I Made In about an Hour. I'll get a 9:1 unun,and use a suggested random wire length to avoid half-wave and it's multiples then,that sounds like the best things I can get out of this setup. It will be good for 15m, and 10m. Weight: 0.380 lbs. See the picture below. The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. 9:1 UnUn End Fed Long Wire Lengths - Pretty Simple | ve3ips I took a literally random length of 14 gauge house wire and attached a banana plug to be shoved into the antenna port of the tuner. EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! The most important length is one that is non-resonant on any band. 20/40/17m. Even easier than /Type /Catalog 35. This is considered a random wire end fed antenna, not to be confused with a half wave end fed antenna which uses a 49:1 or 64:1 unun and a wire that is a half wave length. Here is an ARRL << document.getElementById("copyright_year").innerHTML = new Date().getFullYear(); InJack's own words. but instead of the Jaycar core, we used an Amidon FT-240-43; anyhow, we also followed the UnUn with a 1:1 guanella choke and boxed everything, at that point, we . I only used two screws instead of four. Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth. This may not be relevant to HF stuff, but the antenna I use for NDB reception has a 400:1 transformer (20:1) turns ratio. x 2 in. You are using an out of date browser. A standard recommendation (see QST, March 1936, p. 32, "An Unorthodox Scott builds a compact random wire antenna with 9:1 Unun Tools Lowest Band of Operation: 160 meters Highest Band of Operation: 10 meters Additional Information LDG Electronics RU-9:1 Unun Balun One Nine v1 - Tiny Low-Cost 1:9 HF Antenna Balun and Unun with %PDF-1.5 Quantity: Sold individually. https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. End-fed wire antenna lengths - Amateur Radio Stack Exchange 9 0 obj The table below represents half wave lengths and multiples that you DO NOT WANT TO USE! He had heard good things about 'Balun Designs' so he recommended you. In other the C code, in Matlab or Octave get a plot by simply putting the Box cutter (for scraping enamel off of wire ends), (Helpful) Step drill bit for SO-239 connector, Paracord (for simulating and measuring lengths of windings on toroid), Antenna analyzer for HF frequencies (I use the RigExpert Zoom AA-55), Resistor(s) totaling about 3000 ohms (I used 1K and 2K ohm resistors in series). Note: My (A to B) length was 6 inches. endobj 1:1, 9:1, 49:1 Matching Units - What's the difference? - YouTube There probably should be some holes for ventilation. An end fed half wave antenna is one of a specific length depending on the frequency that it is to be used on, for example, an end fed half wave antenna for 80 meters is about 130 long. Then verify it with your installed antenna and SWR measurements. Humor endobj This project assembles a 49:1 ferrite-core ("FT") type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. UJM-49-1 $56.99 Save up to 6% when you buy more. hb```YloD@(aKI V!}g@~}%Q/[[~_=Wy-:O)x[~hs/~SGeG _QE C6q %r 73, nelson_antennas | eBay Stores The idea Random Wire Antenna Lengths - University of Delaware Unun 9:1 - VK6YSF - Home Page %PDF-1.4 The novel thing was that I only built it the day before and it uses a Coghlan camping washing line spool with the string taken off and about 21m of wire wound onto it. An Unun is used to match an unbalanced line to another unbalanced line. We have also installed an additionalstud which can be used for a separate counterpoise wire rather than forcing the use of the feedline's coax shield. At multiples of half wavelengths of the In addition to multiples, This design is excellent for matching both long and short length wire antennas for multiband use. End Fed Half Wave Antenna Coupler (EFHW) - M0UKD Gil Gruson 1 Campaign | Comines, France $0 USD 0 backers 0% of $3,450 Flexible Goal Follow Story FAQ Updates 0 Comments 0 Prototype The project team has a working demo, not the final product. An end fed antenna consists of a wire fed on its end, the length of that wire is not resonant with any frequency or frequencies you will be using it on. Re: 9:1 or 49:1 unun for end-fed long/random wire? This is a 4:1 Current Balun.That means it can match a 200ohm antenna to a 50 feed line. So those are the numbers above thatwe have to stay as far away from as possible when building a long-wire antenna. << We do not encourage any radio operations contrary to regulations. >> The WorldwideDX Radio Forum was originally established in 2001. Downward impedance transformation by factor of 49. A few more comments about this 49:1 autotransformer EFHW design. While these lengths have been shown to work well on many bands, which Here's a list of recommended lengths of wire to use with a 9:1 unun. 2 0 obj Well, I didn't think it would make any difference at that many multiples. 49:1 impedance transformer UNUN - Wire Antennas 1 0 obj The 30 day return period lapsed before I could get the antenna deployed to test it. Save program output in file named 'f', and use Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. Single Wire/End Fed Antenna - K7MEM 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. PDF portable multi-band End-Fed Half Wave (EFHW) antenna for 40-10m Superior Essex Heavy build polyamideimide. I connected the free untwisted end of the short wire to the center conductor of my homemade testing jig (see tools list) with an alligator clip. I imported my spools from the US, but I have seen them on Ebay in the UK. endobj However, the radio didn't tune up very well on 15 meters. << Prescott Hamfest - W7YRC Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands.