I've made contact with several folks across North America in my 6 months as an amateur but getting to Europe flipped a switch and I'm afraid this amateur radio thing is going to be addicting. << See the picture below. For example, 49:1 UNUN IMPEDANCE XFORMER FOR END FED HALF WAVE ANTENNA. Jack, VE3EED, used center frequencies of thebands described in the article above, and I thought it would be nice to use band edges. You will note that when comparing my results with VE3EED that some of the results are a bit different. Powered by BigCommerce. Each winding is counted when the wire enters through the center hole of the toroid. FCC Information "Just received my new 64131 yesterday and was anxious to see how well it performed. This undesired reflection of RF power back toward the transceiver is identified as a high voltage standing wave ratio (VSWR or SWR). So for 80 meters (say 3.525 MHz) this gives you about 133' of wire. Care to buy us a beer? As an example, a 28-31 foot wire will typically allow 40 thru 10 meter coverage and a 43-50 foot wire will provide access to 80 thru 10 meters. google_ad_height = 600; <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> At this point, Ive only used the 49:1 tap, but plan to take the 64131 whenever I operate portable. %%EOF >> While I have not done so yet, I plan on gluing the test cap to the back of the junction box. Antenna") is an 84' long end fed and a 17' long counterpoise (6.5' for 20m). What these lengths are depend on your tuner and also the wire's surroundings and also the ground system. This antenna, which works on 10, 15, 20, and 40 meters, has a very high impedance of around 2,500 Ohms. 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. The Short Answer Would Be That an UnUn Is a "UN balanced to UN balanced" matching transformer. /Filter [ /FlateDecode ] A level of 500-600 watts is the maximum with a further reduction onany band measuringabove 3:1. Continue on winding the long wire through the toroid to complete loops 3 through 14 as shown in the schematic below. it is easy to pack and easy to install. There are so many new frequencies to stay away from, that it gets pretty tricky for the longer wires. The First Thing New Hams Often Ask:What Is An UnUn? 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. For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. I swept the VSWR of the unun and resistors as described from <1 to 55MHz. ", KiwiSDR Online Radio - 500 ft Northeast Beverage, KiwiSDR Online Radio - 400 ft South Beverage, KiwiSDR Online Radio - 10/11m dipole up 20 meters high. Random wire lengths you should and should not use! presents an extremely high impedance to the tu so that it is not a halfwave multiple of any frequency you want to use. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> is helpful if you're in a hurry to get on the air, read up on the topic The 49:1 impedance transformer will help you bring down the high impedance of your resonant EFHW antenna to almost 50 Ohm. >> Legal Stuff endobj Site Map However, the radio didn't tune up very well on 15 meters. Hi guys,not really hfu related,but I tought I might ask here as I have my account. 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. I will also find some sort of heat resistant packing material to help hold the transformer in place. Just add or subtract as needed a little at a time to get the best compromise. Let's have a look at a few details on how to build a 49:1 impedance . PVC Junction Box(Home Depot), 1 x 1/2 in. If you plan on stringing up a dipole you use 2 equal lengths of wire with the Balun in the middle. For typical tuners built into a rig, 1 0 obj /* Ad banner 160 x 600 */ The key is you want to stay at least 1/2w long but not near 3/4w for any band of interest. 2 0 obj 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. 9:1 or 49:1 unun for end-fed long/random wire? WwS`8o}=n,pjhzRa]Ju/Ru ni4=UvZ:u9*@ Xz+zZcXm}i[Z;Z>.u!*eQVjucXeqYZnSJu)U[n>>KXzZ.Lz sqxcGj]%q}i6=-?YTlnZXV6}=U >5`ZNxChzRa]JU.6TVr6a] Downward impedance transformation by factor of 49. 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. endobj endobj The short piece is for the primary winding of the transformer, and the long piece is for the secondary winding of the transformer. rig, often with no feedline, and the other end in the air attached to Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands. 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. doing the initial 468/f on C and D scales. About Batteries STORE hbbd```b``^ "Cs;D2 I*`0D;+EVUHy`qml0{YVw`b0i DvkAh |"w I2% ?W%@Fg`` 6 A few more comments about this 49:1 autotransformer EFHW design. . << We hoisted the free end of the antenna wire approximately 30 feet into a tree. 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. Re: 9:1 or 49:1 unun for end-fed long/random wire? Twist the short and long wires together starting at an end of each wire. Y &lD30. 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). 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. That's it in a nutshell..or is it? We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. Drill out holes in the designated bottom of the electrical junction box for the SO239 chassis mount. Use with other lengths can potentially damage the transformer depending on power level in use. Odds are that most lengths are fine though, so the easiest solution is to pick a length based on something else (like, the room you have available) and if you get unlucky, roll the dice again. x@ Stacked coreswithwinding configured as 49:1auto transformer. Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. Upon further research, I remade it tightly twisting those two separate wires together, just as it shows in archjeb's picture, and it worked surprisingly well. In another life, I could have been a telephone engineer. Par EF 20 and par EF 40 (I realize for 17m I would prob just add that band to a 49:1 balun) That's that my question is. A png image named g.png will be created. 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. 7 0 obj 3 0 obj /CropBox [0 0 748 752] They just saved you and I loads of time and frustration. 1 bolt for antenna hook up (with nuts, washers, lock washers, and possibly thumb screw; I used #8 diameter, about an inch or so in length.). >> However, the list has been revised and is good for wires as long as 500 feet. End Fed Half Wave Antenna Coupler Schematic - 7-30MHz. 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. A 9:1 matches 50 ohms to 450 ohms and that turns out to be an ok compromise for feeding 50-100ft of wire for general purpose SW receive. /ProcSet 7 0 R >> 22.00 + 5.00 Postage. Ham Satellites An Unun is used to match an unbalanced line to another unbalanced line. On our next windy free day, AA1F and . thank you. Ham Hints x 2 in. This project assembles a 49:1 ferrite-core ("FT") type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. unavailable, a random wire can save the day, but it is important to This article details the construction of the transformer. 40-30-20-15m bands for my 4 band Elecraft K1 qrp rig. The popular End-Fed Half-Wave (EFHW) Antenna is an easily portable, high-impedance (2,000-4,000 ohm) wire antenna that resonates on its fundamental frequency and all harmonics above. The counterpoise wire, This transformer is designed to be used with an end fed, Approx. 27.00 (27.00/Unit) Free Postage. "I received my third balun from Balun Designs this afternoon. <> Built with the same craftsmanship as all our other units, this new model will allow you to either replace your current matching unit or construct a new higher powerend fed half wave antenna. Start winding the toroid with the twisted wires at loop #1 (see schematic below). $1YacO5Q}YC\>qZ } /Contents 5 0 R /Creator (XnView) Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. 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. REVISED: 16 19 22 26 32 33 38 44 46 48 52 64 65 66 76 78 80 88 92 95 96 99 104 110 112 114 123 128 130 132 133 138 144 152 154 156 160 165 171 176 182 184 190 192 195 198 208 209 220 224 228 230 231 234 240 242 246 247 256 260 264 266 272 276 285 286 288 297 304 308 312 320 322 323 325 330 336 338 342 352 361 363 364 366 368 369 374 380 384 390 396 399 400 414 416 418 429 432 437 440 442 448 455 456 460 462 464 468 475 480 484 494 495 496. Attaching a counterpoise wire to the common point of the auto-transformer provides the antenna radiator something to push against rather than the coax shield. It is important to use a counterpoise. /Type /Page 9 0 obj Longer wire is always more NOTE: Rewording the previous paragraph, if you have a capable enough