So for 80 meters (say 3.525 MHz) this gives you about 133' of wire. 73, I'm looking forward to getting off work and hitting 40 & 20 meters again!! An UNUN is needed to match the high impedance of an end fed antenna (2k-4k ohms range). About Batteries Figure 3 Wiring of the 9:1 voltage unun. endobj 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. One end goes straight into the % The fewer bands, the fewer high impedance regions to avoid. Hope it's clear now, if not. Y &lD30. Presented for your consideration by Jack, VE3EED. http://udel.edu/~mm/ham/randomWire/. In other Therefore, we came up with the following numbers to avoid (IN FEET): These lengths in the table beloware the culprits that cause all of the trouble when using random lengths. Theme: Newsup by Themeansar. google_ad_height = 600; You can add your own wire or get the complete product from this link EFLW-3K antennas. =======================, More on Random Wire Lengths from Mike, AB3AP (06-29-2012), I was surfing around Hamuniverse.com and found thIs page on random wire antennas: A so-called random wire antenna is an end fed antenna. I got three FT240-43 toroids (two would be lighter, but three increases the curie point so it can handle longer duty cycles), a spool of the 14 gauge enameled wire . 2 eyehooks with washers and nuts (I used #8 diameter, but size is up to you.) presents an extremely high impedance to the tu Repeater Basics I have not done this yet. An Unun is used to match an unbalanced line to another unbalanced line. NOTE: Rewording the previous paragraph, if you have a capable enough are easily converted to half wavelengths by the famous 468/f generally The kit includes the parts needed to construct a 49:1 impedance matching network, which will transform the impedance to 50 Ohms, which will suit most transceivers. Some important and helpful references I used for this work: https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. 4 0 obj Superglue 2 toroids together. You'll want to have that wire up as high as you can get.. The counterpoise wire, This transformer is designed to be used with an end fed, Approx. Lengths to avoid are not always the same as 9:1 UnUn End Fed Long Wire Lengths - Pretty Simple. Please note that I will not be describing the construction of the antenna wire radiator here. We'd really appreciate it! "Just received my new 64131 yesterday and was anxious to see how well it performed. 2. 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. The length should be calculated based on the lowest frequency to be worked. I made one without doing this and it didn't work so well. /Width 748 I sent him the link to the 49:1 unit to get his feedback. Power Handling (CW/SSB): 100 W/200 W Enclosure Width: 2.500 in. ?7{*. frequencies for your country or favorite modes. In stock . 40-10m with a 49:1 Unun. 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. For instance, to work 40m be sure the antenna is at least 10m or 33' long. Ham Radio Videos! Use with other lengths can potentially damage the transformer depending on power level in use. So after much frustration..down it comes and you go on to a totally different type of antenna.all that time just wasted inyour opinion..until now! In the first year using this unun with a random length endfed wire (Aluminum Elec fence wire at that) I managed to confirm WAS via LoTW on 10m, 15, 17, 20, 30, 40, 80. . google_ad_client = "ca-pub-9377297764300878"; Tweak the antenna length if necessary and then maybe adjust the turns ratio again. which got me thinking. UJM-49-1 $56.99 Save up to 6% when you buy more. I connected it to a 33 wire running from my balcony, through the trees, and ran WSPR overnight to check things out. /Height 752 <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 59 0 obj <>/Filter/FlateDecode/ID[<81C501BAF3AD19DF6B2122F37F15AF84>]/Index[25 50]/Info 24 0 R/Length 149/Prev 898971/Root 26 0 R/Size 75/Type/XRef/W[1 3 1]>>stream unavailable, a random wire can save the day, but it is important to <> /Type /XObject For those that enjoy the LNR and Hy Endfed antennas, but want to run more power, 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, ttaching a counterpoise wire to the common point of the auto-transformer, provides the antenna radiator something to push against rather than the coax shield. . Superior Essex Heavy build polyamideimide. q "Can you please recommend schematics that are designed to tune setups like these? Ultimately, this housing works fine, but it is heavy and clunky.). you're using different ham bands than in these examples, modify and rerun 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. This design is excellent for matching both long and short length wire antennas for multiband use. The QRP End-Fed Half-Wave Antenna 49:1 Transformer Building a great impedance transformer for Ham Radio end-fed wire antennas. ), Note that Jack, VE3EED,went SK several years agohe will be missed. The length should be calculated based on the lowest frequency to be worked. Each vertical blue line represents an amateur radio band. 40-30-20-17. tuner the colored bands below are the best lengths as long as your /Resources << bands as possible. >> Theme designed by Papathemes. Just add or subtract as needed a little at a time to get the best compromise. Even easier than config file by typing gnuplot rw.gnu. SWR will vary based on topography, wire orientation and use of ground or counterpoise. 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 most common question I get asked is what is the correct length for my End Fed Long Wire Antenna? &nb so that it is not a halfwave multiple of any frequency you want to use. "I received my third balun from Balun Designs this afternoon. understand its properties. Here is an ARRL Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. (Note: I am not satisfied with this part of the project, so I will describe it here briefly. That is the 10th multiple of a half wave on 15 meters. 9:1 or 49:1 unun for end-fed long/random wire? x 2 in. SEARCH EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! 31 The WorldwideDX Radio Forum was originally established in 2001. This transformer is designed to be used with an end fed half wavelength of wire only. (A t0 B) Fold over 6 to 8 inches and twist it together. /ModDate (D:20221212112042) 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.). uR5ucE`_aksLjYT=hzRa]JucX7d}|'}`XRa>X Twist the short and long wires together starting at an end of each wire. endobj document.getElementById("copyright_year").innerHTML = new Date().getFullYear(); 4 0 obj stream Here Is a 250 Watt Home-Brew That I Made In about an Hour. Hopefully these random wire length calculations will help us all make this "easy" antenna work better! 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 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. Tools Anyway, an old friend mentioned 'MyAntenna.com' but they were closed for the summer. 2 0 obj For example a 32 foot length is actually a half wave on 20m with an impedance of about 3500 ohms and requires a 50:1 balun. 49:1 or other high ratio transformers are for resonant "cut to frequency" antennas like the traditional zepp/fuchs antenna. HF & Shortwave Feeling a bit too lazy to calculate that by hand, however, I wrote a /Parent 3 0 R Code Practice Even better would be shortening to 53'. 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. 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. SO-239 connectors are silver plated with Teflon insulation. /ProcSet 7 0 R >> This project assembles a 49:1 ferrite-core ("FT") type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. 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. V#X~[Z?\ZcX:-Y?&Y?IqTnayZ{jTZOub}=UTWu1G>o.,RaT c=W>:sECXTkc=X >> Solder a the 100pF capacitor between the center conductor wire and ground wires. stream My commercial EFHW is 130 feet long for 80 and up, and my 40 meter homebrew antenna is about . So those are the numbers above thatwe have to stay as far away from as possible when building a long-wire antenna. used by hams for dipole lengths. Vhf and Up 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. stream So for example 80m could range in length from 120 to 133 feet. 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- The "9:1 UNUN" are for random length wire antennas fed at the end. is helpful if you're in a hurry to get on the air, read up on the topic This homebrew 49:1 impedance transformer is the heart of any EFHW antenna you will build, most of the time. The random wire antenna is probably one of the least expensive, easiest and cheapest HF antennas to use if you have a tuner and you want to get the "most" out of a length of "random" wire without having to pull out that calculator, doing the math, getting the center insulator built orbought, running the feedline, and all the rest that goes with putting up a more elaborate antenna. 9:1 Unun 1.5-54MHz 2kW 9132S. Hi guys,not really hfu related,but I tought I might ask here as I have my account. /Name /Im0 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. The most important length is one that is non-resonant on any band. I have never tried to transmit through it, but it proved the optimal ratio for receiving with my setup. Caution: When used atfull power rating of 1kW, the antenna must have a low SWRon the band selected and be used on a 50% duty cycle. In another life, I could have been a telephone engineer. Thank you so much for such a great product! 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 . The matching unit The impedance at the end of a half wave antenna is somewhere between 2000-5000 Ohms. We hoisted the free end of the antenna wire approximately 30 feet into a tree. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 35. I plotted the results for the U.S. CW band edges for use with my4 band Elecraft K1 qrp rig. The ratio doesn't need to be 49:1 2,400 ohm either, other ratios will transform to other impedance. You will note that when comparing my results with VE3EED that some of the results are a bit different. 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. https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. 5 0 obj This is a 4:1 Current Balun.That means it can match a 200ohm antenna to a 50 feed line. I have found this calculation to work well, however it depends on many factors such as wire used, location etc. 1936 article, however, fall in line with 468/f and so is used here. /Contents 5 0 R >> Save program output in file named 'f', and use x][~ XwiH:99gn`1-wz;n[VbW7JH4D]>}>y/D_^7,yyx}s*nveo>mn|6k7GMY4%" M)?O|'opw8o1\5JNe:9hTc5@Ik~aE%O^0$ 0E 'BX2?R!t&^E"3oqbW |${boEU>jU:]bQW?4, u1'^`oQ_4E 0~y L^'y}-RHV8L KSZ?mF4lTv'r^mF|":e}?VdTm7bGR]PchDpb*{*HGJ-m)bC!EX"iM%8L7O7-=jcn+D{_' I HH~v70J^9$.7m]knq)L(UQ%OrK:nn!8*EP It will be good for 15m, and 10m. A way of connecting the analyzer to the transformer. hb```YloD@(aKI V!}g@~}%Q/[[~_=Wy-:O)x[~hs/~SGeG _QE C6q %r N4UJW. If the choices are. Shortwave Listening ones The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Designed for those who want the maximum isolation and choking across the full HF spectrum. Use only the white gaps for your antenna lengths, and if 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. 74 0 obj <>stream He had heard good things about 'Balun Designs' so he recommended you. The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. %PDF-1.7 (Originally published February 22, 2021). , Reprinted with permission of Hamuniverse, this is an excellent explanation of SWR and how to best me License Study As typically The key is you want to stay at least 1/2w long but not near 3/4w for any band of interest. Recommended wire lengths for Unun models 9130, 9132 & 9135 Table shows typical SWR relative to installed wire length. Thanks for your answer,I will probably go with the 9:1 then. This Balun Designs unit is replacing an MFj 1982 HP EFHW balun that was DOA when it arrived last May. K1S Valentines Are (Almost) Out The Door! << Do what works best! 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. If the transformer is used with an externaltuner in conjunction with a single wireantenna typically 130-135 feet in length, power should be reduced on those bands that show an SWR above 1.6 to2:5 withoutthe tuner. This was 9m vertically metres up a fishing pole and then about 5.8m out. So a 49:1 impedance transformer is needed to match the 50 ohms of the coax at the feed line. the C code, in Matlab or Octave get a plot by simply putting the Continue on winding the long wire through the toroid to complete loops 3 through 14 as shown in the schematic below. 6 Screws/ Nuts/ Washers/Wing Nuts And Ring Connectors, 1 X Mica Capacitors 100pF 500V 5%(Mouser Electronics), 1 x 4 in. VSWR analysis of the antenna in the field showed that VSWRs between 3-5.5 from 40M to 10M. /Producer (XnView, http://www.xnview.com) 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). it is easy to pack and easy to install. and leave the unun on the ground. You have to stay away from a half wavelength on any frequency. 1 0 obj If you plan on stringing up a dipole you use 2 equal lengths of wire with the Balun in the middle. 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. 7 0 obj Click to enlarge. 20/40/17m. Both were on 20 meters at 97 watts, Icom 7300. endobj The following wire connections do not need to be made in the order I described. Drill a hole in the top for an eyehook (to be used to secure the unun to whatever it is you want to hang it from.). IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. 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). It's an efficient way to get all the multiples A level of 500-600 watts is the maximum with a further reduction onany band measuringabove 3:1. 1 0 obj See the picture below. At this point, Ive only used the 49:1 tap, but plan to take the 64131 whenever I operate portable. I will also find some sort of heat resistant packing material to help hold the transformer in place. 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. Experimenting by slightly changing the wire length (+ or-) is encouraged to provide best overall performance. Re: 9:1 or 49:1 unun for end-fed long/random wire? << End fed 49:1 60ft wire (using coax as the counter poise. Ham Radio News! When do you use a 1:1, 9:1 or a 49:1 balun? After winding #2 is made and extends down the backside of the toroid, untwist the wires. For instance, to work 40m be sure the antenna is at least 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 . Our newdesign isperfect for matching both long and short length wire antennas for multiband use. 0 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. /CropBox [0 0 748 752] This transformer converts the impedance at the end . Stacked coreswithwinding configured as 49:1auto transformer. well, the main antenna wire goes to the 9:1 UnUn "+" connector, the vertical counterpoise (insulated !) % <> Alternate connectors and Mounting Options are available in the. Well, I didn't think it would make any difference at that many multiples. For example, This design is excellent for matching both long and short length wire antennas for multiband use. The unun was floating at about 15 feet above ground. Downward impedance transformation by factor of 49. 73. JACK, VE3EED are blocked out because an antenna should be at least that long. 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. In addition to multiples, /Pages 3 0 R This is a followup video to #344 where I assembled the 49:1 UNUN kit from HF-Kits / ARRL. You have to give up a band or two, like 60m and 6m, as There are numerous configurations available online that will accomplish this on multiple bands (Google search "end fed half wave antennas"). Free Postage. Dimensional Drawing of Standard Enclosure, 1:1 Common Mode Choke / Noise Suppression, Core Material Selecton for Baluns and Ununs, Antenna Matching Problems When Using Ladder Line or Open Wire Feedlines, Model 4932 - 4 & 9:1 Unun 1.5 - 54MHz - 2kW, Model 49130 - 49:1 - 80-10m EFHW - 200 watts, Model 64131e - 64:1 & 49:1 - 80-10m EFHW - Up to 1kW, Model 4116 - 4:1 Hybrid Balun 1.5 - 54MHz 3kW, Model 9130sw - QRP 9:1 Unun 1.5 - 54 MHz - 300 watts, Model 1115d - Max Choking 1:1 Balun, 1.5-54 MHz, 5kW. Jack, VE3EED - SK. transmit frequency the impedance is so high that tuners in most rigs Using a 49:1 transformer shoot for the best 50 match @ appx 2450 load over your working frequency bands. You also want the antenna to be at least 1/4 wavelength long for each band you plan to use. Enclosure Depth: 1.250 in. Start winding the Matching Auto Transformer, each pass through the center of the core equals one turn. (Center fed is so appealing because you avoid this.). Mike ab3ap, Editors note: Many thanks to Jack, VE3EDD (SK)and Mike, AB3APfor sharing their math and computerskills with us. SO-239 (UHF female) chassis mount with screws, nuts, lock washers. Because I'm more visually oriented I then plotted the many overlapping "red zones" and ended up with the page at: Bullet 50:450 (9:1) HF Unun, 1.8-61 MHz, 1500 Watts, End Fed Antennas. Usually any wire length that is non resonant, like those shown above, will work with the 4:1 ratio. 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. u?X`f0&/Ri;W0Tn_*TX:ug Drill a hole in one side for the antenna radiator wire mount (for a #8 bolt in my build). [ /PDF /Text /ImageI ] JC[ d8O[UKKQ{yZ{G 'Upno_*~8uo a@G`' zxUHXW&`}mEp`?i0 oE:N0-/t"t.-? 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] Tune Around! You can take one of these 49:1 transformers and use the 468/freq (Mhz) formula to calculate the length you need in feet. /* Ad banner 160 x 600 */ Cut the antenna radiator wire (free untwisted end of long wire) of the unun to the correct size, scrape the enamel insulation off of the free end with a box cutter, add a ring terminal, and secure to antenna radiator bolt with washers and lock washers. Legal Stuff endstream STORE thank you. /Count 1 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. So is an essential piece of gear to have. 75/80 METER RESONATOR KIT FOR THE UJM-EFHW-40-10 200W 40-10m ANTENNA 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). The free end of the untwisted portion of the long wire (past the 14th winding) will be secured to this bolt as well on the inside of the box, while the radiator will be secured to it on the outside. 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. . /Type /Page About Hamuniverse SBULLET-9U-1500. 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. , This is a partial reprint (with permission) of an excellent series of articles published by KV5R Powered by BigCommerce. A few more comments about this 49:1 autotransformer EFHW design. The vertical (y-) axis shows the VSWR and the horizontal (x-) axis shows the frequencies. Antenna") is an 84' long end fed and a 17' long counterpoise (6.5' for 20m). good show chuck, you said ya picked up a 430, did i tell i fried the 0ne i got from you, can anyone point me in the direction of a 2 pill schem for the HG 2879? A standard recommendation (see QST, March 1936, p. 32, "An Unorthodox 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. 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. The bandwidth where SWR was below 2:1 was about one MHz. The graph below shows lengths to avoid for different collections of bands. CQ-Calling All Hams! Here's a list of recommended lengths of wire to use with a 9:1 unun. Placing 3000 to 4000 ohms of resistance between the free end of the twisted portion of wires (the gound) and the free end of the long wire (the wire that connects with the antenna radiator after the 14th winding), can simulate adding an antenna radiator wire to the unun impedance transformer. I used 2000 and 1000 ohm resistors in series connected to the proper unun wires with alligator clips for a total of 3000 ohms. << One is for the top of the box so that it can be hung up. $1YacO5Q}YC\>qZ } 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). 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. << endobj (Also check out AB3AP'Swebsite and say thanks for sharing his skills. wire lengths less than 1/4 wavelength of the lowest desired frequency 35. W3EDP's results in the above referenced A small ring terminal for 14ga wire that fits these screws would be helpful too. endobj installed, it is a compromise antenna but great for portable use because Reading Room These dimensions were derived from modelling the antenna in EZNEC. End Fed Antennas. 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). An excellent way to attach a long wire antenna to the Ham It Up, this 1:9 balun has an SMA output port and high-quality spring-type terminal block input for your coax.
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