<>>> Here Is a 250 Watt Home-Brew That I Made In about an Hour. Theme designed by Papathemes. The "Almost Random" Wire Antenna - KB6NU's Ham Radio Blog K1S Valentines Are (Almost) Out The Door! Let the now free end of the short wire hang down from the toroid. Ham Hints Links /ProcSet 7 0 R >> For typical tuners built into a rig, 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 . I actually did this first and before the connector was bolted to the box. 4 0 obj . 40-10m with a 49:1 Unun. After winding #2 is made and extends down the backside of the toroid, untwist the wires. x[q;`&z`uAlo#V@;hvOYt, @*Ys~_W_~W_aw_ p[N+}[t-^oLy}xz>7/~c|ZZt75;kN^=>Y+_~|b~"m*tw>xG=x6Qwz|xvz- He knew that in order for the tuner to "see" a fairly low swr to work within it's range,that the antenna had to be NOT A HALF WAVE ON ANY FREQUENCY that we wanted to us, because a half wave will give us a very high impedance and the resultingswr into a 50 ohm transmitter! HF & Shortwave It's an efficient way to get all the multiples Multi-band end-fed - Nonstop Systems this The trick, therefore, is either This is the latest and greatest transformer design for End Fed Half Wave (EFHW) antennas. I'm consistently pleased with the quality and ease of use of Balun Designs products and look forward to my next purchase in the future. 49:1 UNUN IMPEDANCE XFORMER FOR END FED HALF WAVE ANTENNA. Feeling a bit too lazy to calculate that by hand, however, I wrote a 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. So I just wanna say thank-you!! Scott builds a compact random wire antenna with 9:1 Unun SEARCH Nelson Antennas 9:1 balun - eHam.net Bullet 50:450 (9:1) HF Unun, 1.8-61 MHz, 1500 Watts, End Fed Antennas RFI Tips and Tricks Balun Designs. In theory, my LDG Z100 Plus autotuner should be capable of matching the impedance of this 49:1 transformer with a end-fed half wave length antenna radiator across all amateur HF bands. V#X~[Z?\ZcX:-Y?&Y?IqTnayZ{jTZOub}=UTWu1G>o.,RaT c=W>:sECXTkc=X The key to end fed antenna success is the matching network interface between the long wire antenna and the coax feed line and feed line choke at the transceiver. This antenna, which works on 10, 15, 20, and 40 meters, has a very high impedance of around 2,500 Ohms. 3 0 obj The most common question I get asked is what is the correct length for my End Fed Long Wire Antenna? /ModDate (D:20221212112042) The First Thing New Hams Often Ask:What Is An UnUn? Vacation Closure - See Homepage for Next Availability. 1936 article, however, fall in line with 468/f and so is used here. FCC Information NEMA rated 4x marine grade junction box for outdoor installations. (wlSR9dJ_x%+VHX4FRr 3>;g^x%g'wkJu,i~#Q"2|WGf[!_m]#&1$)R.{--" 'dGO;=_B$T}". /Im0 Do I connected the free twisted end of the short and long wires (the ground) the chassis wire (ground) of my homemade testing jig with alligator clip. Our newdesign isperfect for matching both long and short length wire antennas for multiband use. j#f5(fk0?P[polEo5b2-/oVZu1Qo-I6C/M@TbddPc#cdZZ|7+|o{}!F#?Go7ju|?wwgow/c2/W-m~~hn[S29OU}}r7lc]wsw[shS[#qbrrK[7*0,Xv{k+o {=*vo S__O~*=y/zk75O?yjCnXS{`~Ii'c_GxN. /CropBox [0 0 748 752] Experimenting by slightly changing the wire length (+ or-) is encouraged to provide best overall performance. AndWhat Is It Used For In Antennas? When you're antenna (or radial) length's an odd multiple of the operating freq, you may not need a balun or even a transmatch. Prescott Hamfest 2023 Saturday - May 13, 2023 - 0800 to 1200 MST Granville Elementary School 5250 Stover Drive, Prescott Valley, AZ 86314 The 2023 Prescott Hamfest is co-sponsored by the Yavapai Amateur Radio Club (YARC) and the Amateur Radio Council of Arizona (ARCA). endstream endobj startxref Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW - Balun Designs 0 9:1 Magnetic Longwire Balun / Unun - M0UKD - Amateur Radio Blog high the other 1.5m (4.5feet). 9:1 Unun 1.5-54MHz 2kW 9132S. Following the directions exactly as specified (0.47wl / 0.05wl matching counterpoise) and drilling two weep holes in the appropriate position, I had a 10 meter EFHW antenna up in less than ten minutes. /Type /Page Just a note, if you make one of these yourself, you need to twist together the first two wraps of the 14 winding wire with both wraps of the two winding wire. Several ways exist to bring the wire's high impedance feedpoint closer to the desired 50 ohms, including use of a 49:1 or 64:1 unun, which eliminates the need . 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. /MediaBox [0 0 748 752] Lengths for Long-wire Antennas Jack - VE3EED Recommended lengths: 29 - 35.5 - 41 - 58 - 71 - 84 - 107 - 119 - 148 - 203 - 347 - 407 - 423 Not recommended lengths: 16 - 19 - 22 - 26 - 32 - 33 - 38 - 44 - 46 - 48 - 52 - 64 - 65 - 66 - 76 Swr usually is all over the place and the tuner will just not do it's job. stream Quantity: Sold individually. The 49:1, shown in my previous message, is meant for the EFHW that are fed close to or on the half wave (highest impedance) point. 3 0 obj We recently found some good information about random wire lengths that you should and should not use. /CreationDate (D:20221212112042) Hi guys,not really hfu related,but I tought I might ask here as I have my account. Because I had some spare Cu-Wire I wound another 1:49 Unun on a smaller FT-140-43 toroid and tried different capacitors between feedline and ground (to compensate for the 10m band). It is not a good choice for working lower bands from a too short wire, that is, if you have cut your wire to a 20m halfwave, it ain't much punkin' for 40m, 80m, or 160m. HF Underground wiki Radio Hobbyist technical blogHFU Discord EuroPirate ChatPropagation DataTeamspeak Server, TDK CXA-2090 LCD Inverter Module New Old Stock USA Seller $19.99, Shortwave Pirate Radio In North America And Around The World, And Other Signals That Go Bump In The Night, Login with username, password and session length. The vertical (y-) axis shows the VSWR and the horizontal (x-) axis shows the frequencies. Care to buy us a beer? endobj My homemade 49:1 EFWH with a 60 wire (cut for 40M) would do just fine! My commercial EFHW is 130 feet long for 80 and up, and my 40 meter homebrew antenna is about . The most important length is one that is non-resonant on any band. (Originally published February 22, 2021). When do you use a 1:1, 9:1 or a 49:1 balun? 74 0 obj <>stream google_ad_slot = "1982258389"; End Fed Half Wave 40-10 Wire Antenna - N6DOZ Contact Mike ab3ap, Editors note: Many thanks to Jack, VE3EDD (SK)and Mike, AB3APfor sharing their math and computerskills with us. doing the initial 468/f on C and D scales. There are so many new frequencies to stay away from, that it gets pretty tricky for the longer wires. He was so impressed that he purchased a 9:1 unit from you, his will be delivered Saturday. End fed 9:1 58ft wire and 17ft counterpose wire touching ground. Anyway, an old friend mentioned 'MyAntenna.com' but they were closed for the summer. SSTV Jack, VE3EED, hopefully has solved a major headache we all have when we attempt to go thru the trial and error and frustration with getting the random wire to work where WE want it to work. 9:1 or 49:1 unun for end-fed long/random wire? We hoisted the free end of the antenna wire approximately 30 feet into a tree. Cut a 4 foot length of AWG #18 enameled wire. About Hamuniverse Modify bands and presents an extremely high impedance to the tu EFHW unun Resonant Long Wire 49:1 Transformer With 67' Antenna Wire. Usually any wire length that is non resonant, like those shown above, will work with the 4:1 ratio. In other Some important and helpful references I used for this work: https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. About Batteries (The numbers aboveare a great start, thanks to Jack and Mike! The fewer bands, the fewer high impedance regions to avoid. That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . Solder a the 100pF capacitor between the center conductor wire and ground wires. This transformer is designed to be used with an end fed half wavelength of wire only. In stock . You need to use these lengths and the longer ones . However, the radio didn't tune up very well on 15 meters. 27.00 (27.00/Unit) Free Postage. "Just received my new 64131 yesterday and was anxious to see how well it performed. endstream Ham Radio Videos! In total 29 contacts were made from British Columbia to Texas to Florida in 40 minutes on 20M. Liquidtight NM 90-Degree Connector(Home Depot). So those are the numbers above thatwe have to stay as far away from as possible when building a long-wire antenna. I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. Let's have a look at a few details on how to build a 49:1 impedance . Designed for use with single wire unbalanced antennas, this new addition is small, compact and perfect for quick portable/emergency installations. For reasons that I do not understand, adding a capacitor between the coax conductor wire (untwisted free end of short wire) and the ground (twisted free ends of long and short wire) can increase the functional bandwidth of the antenna on the higher HF frequencies. Re: 9:1 or 49:1 unun for end-fed long/random wire? Two pieces of 14 gauge enameled wire (e.g., Thermalese), one short piece (about 1 foot in length) and one long piece (about 7 feet in length). CQ-Calling All Hams! A standard recommendation (see QST, March 1936, p. 32, "An Unorthodox stream are easily converted to half wavelengths by the famous 468/f generally 2 0 obj When you're 1/2w long you're around 2k ohms or more where the balun won't under or over xform; as you approach 3/4w your z is going to drop to where a coax match can be made just by soldering the wire to the center conductor sans balun - more or less the principle of the windom and ocf dipole. 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!! Enclosure Depth: 1.250 in. 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. The QRP End-Fed Half-Wave Antenna 49:1 Transformer Building a great impedance transformer for Ham Radio end-fed wire antennas. 40-30-20-17. endobj The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. You'll want to have that wire up as high as you can get.. It is used fornon-resonant verticals like 43 foot or 33 foot Or Wire antennas like an End-Fed1/2 Wave Multiple Length Wire Antenna. A 9:1 unun is a transformer that reduces the impedance at the input by a factor of 9. 35. I connected it to a 33 wire running from my balcony, through the trees, and ran WSPR overnight to check things out. I did not want to put the transformer in the housing until I tested it. The length should be calculated based on the lowest frequency to be worked. BUILD INSTRUCTIONS FOR 49:1 UNUN IMPEDEDENCE TRANSFORMER: WX1MAR and I brought the DIY 49:1 unun with a borrowed antenna radiator wire cut for 20M half-wavelength to Ashland State Park K-2417 in Massachusetts for a Parks-on-the-Air (POTA) activation. %PDF-1.5 % I have used the 49.2 ft (15 Meter) length of wire on vacation with both automatic tuners and an MFJ Model 16010 tuner with good results for 40, 20, 17, and 15 Meter operation. PDF 33ft Verticals and 4:1 Ununs - G8JNJ 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. http://udel.edu/~mm/ham/randomWire/. Hopefully these random wire length calculations will help us all make this "easy" antenna work better! 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. %PDF-1.4 ", KiwiSDR Online Radio - 500 ft Northeast Beverage, KiwiSDR Online Radio - 400 ft South Beverage, KiwiSDR Online Radio - 10/11m dipole up 20 meters high. 1. This calculates to 4.2 m or 14 ft for an 80m end-fed. 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. /Contents 5 0 R endobj A few more comments about this 49:1 autotransformer EFHW design. Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. 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. Vhf and Up /Height 752 That is the 10th multiple of a half wave on 15 meters. 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. an auto-tuner at the base vs. the same antenna fed a 4:1 balun wound with 75 ohm coax on two separate type 43 ferrite cores and a remotely sited tuner fed via 200ft of low loss LDF2-50 coax vs. a broadband antenna of the same element length.
