June 8, 2022 at 9:17 am. "I received my third balun from Balun Designs this afternoon. are easily converted to half wavelengths by the famous 468/f generally 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 article details the construction of the transformer. 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.). a more capable tuner - see AA5TB's The ratio doesn't need to be 49:1 2,400 ohm either, other ratios will transform to other impedance. Downward impedance transformation by factor of 49. W3EDP's results in the above referenced The Short Answer Would Be That an UnUn Is a UN balanced to UN balancedmatching transformer. Usually any wire length that is non resonant, like those shown above, will work with the 4:1 ratio. Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. A good place to start is the formula 468 / f (MHz) for a 1/2 wavelength wire antenna. 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. the C code, in Matlab or Octave get a plot by simply putting 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. Tools /Subtype /Image 1936 article, however, fall in line with 468/f and so is used here. 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. ones Continue on winding the long wire through the toroid to complete loops 3 through 14 as shown in the schematic below. 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. uR5ucE`_aksLjYT=hzRa]JucX7d}|'}`XRa>X This transformer is designed to be used with an end fed half wavelength of wire only. SSTV 2 0 obj The vertical (y-) axis shows the VSWR and the horizontal (x-) axis shows the frequencies. Here they are in order: 75/80 METER RESONATOR KIT FOR THE UJM-EFHW-40-10 200W 40-10m ANTENNA A VSWR sweep of the unun after adding a 100pF capacitor shows an SWR <5:1 from 160M to 10M. are blocked out because an antenna should be at least that long. . these are the worst lengths and you want to be as far from colored I have not done this yet. 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 . /CreationDate (D:20221212112042) Stacked coreswithwinding configured as 49:1auto transformer. >> transmit frequency the impedance is so high that tuners in most rigs 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. EFHW unun Resonant Long Wire 49:1 Transformer With 67' Antenna Wire. 49:1 End Fed Half Wave Antenna 40-10M 100W Version Bands of operation 40,20,15 & 10m using 67 feet of our UV, Ozone resistant Antenna wire. The WorldwideDX Radio Forum was originally established in 2001. stream It is used for non-resonant verticals like 43 foot or 33 foot Or Wire antennas like an End-Fed 1/2 Wave Multiple Length Wire Antenna. You need to use these lengths and the longer ones . Shortwave Listening I say run what you got and don't worry about it. You'll want to have that wire up as high as you can get.. Privacy Policy For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. This is to avoid the antenna radiator from acting like a resistor, and thus instead of radiating radiofrequency energy produced by the transmitter, sending it back down the coax toward the transmitter. In fact, the 9:1 unun that I built is actually an autotransformer. endstream Each vertical blue line represents an amateur radio band. 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. 2. Humor The "9:1 UNUN" are for random length wire antennas fed at the end. HF Underground wiki Radio Hobbyist technical blogHFU Discord EuroPirate ChatPropagation DataTeamspeak Server, TDK CXA-2090 LCD Inverter Module New Old Stock USA Seller $19.99, Shortwave Pirate Radio In North America And Around The World, And Other Signals That Go Bump In The Night, Login with username, password and session length. Step 1: Drill holes for and install the SO-239 or BNC connector, the stainless steel machine screw antenna connector and the ss machine screw ground connector. NEMA rated 4x marine grade junction box for outdoor installations. Suggested wire lengths for 1-61 MHz operation (measured from Bullet wire point): Bands Covered (meters) Wire Length (feet) Minimum Coax Length (feet) 40-30-20-15. It is important to use a counterpoise. Performance is ASTOUNDING, far exceeding my expectations. x][~ XwiH:99gn`1-wz;n[VbW7JH4D]>}>y/D_^7,yyx}s*nveo>mn|6k7GMY4%" M)?O|'opw8o1\5JNe:9hTc5@Ik~aE%O^0$ 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 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. In other I wrote a small C program that does just what Jack did, butI used the band edges. This homebrew 49:1 impedance transformer is the heart of any EFHW antenna you will build, most of the time. and experiment. The 49:1 End Fed Half Wave Antenna is very popular choice for home & field use, Ideal for limited space and stealth applications. The trick, therefore, is either 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! endobj endobj This design is excellent for matching both long and short length wire antennas for multiband use. Connect this ring terminal to one of the SO239 chassis bolts. Balun Designs. The First Thing New Hams Often Ask:What Is An UnUn? 2 0 obj "Here's the word on random-wire antennae.". 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. (Also note that here may be instances where the suggested lengths may not work exactly due to the many variables in the surroundings of the antenna, wire length variances, your tuner, it's height above ground, it's construction, etc. In total 29 contacts were made from British Columbia to Texas to Florida in 40 minutes on 20M. Using a 49:1 transformer shoot for the best 50 match @ appx 2450 load over your working frequency bands. /ProcSet 7 0 R >> (Note: I am not satisfied with this part of the project, so I will describe it here briefly. 2 0 obj Meet 'Balun One Nine', a small, cost-effective balun. Our Ask An Elmer panel discuss this question - what's the difference between matching units?Please consider using. The bandwidth where SWR was below 2:1 was about one MHz. 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. 9:1 UnUn End Fed Long Wire Lengths - Pretty Simple. 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. 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. 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. Ham Radio Videos! /Kids [ 4 0 R ] 1 0 obj <> Cut a 4 foot length of AWG #18 enameled wire. /Producer (XnView, http://www.xnview.com) Wire lengths for the 4:1 ratio in models 4932 and 4935. For instance, to work 40m be sure the antenna is at least 9:1 Unun 1.5-54MHz 2kW 9132S. This type of antenna is very easy to install because there is no need . We hoisted the free end of the antenna wire approximately 30 feet into a tree. document.getElementById("copyright_year").innerHTML = new Date().getFullYear(); <>/Metadata 239 0 R/ViewerPreferences 240 0 R>> "Can you please recommend schematics that are designed to tune setups like these? As typically Free Postage. 74 0 obj <>stream wire is at least 1/4 wavelength. 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. So for 80 meters (say 3.525 MHz) this gives you about 133' of wire. 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. well, the main antenna wire goes to the 9:1 UnUn "+" connector, the vertical counterpoise (insulated !) =======================, 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: /XObject << /Im0 9 0 R >> all US ham bands. &nb That is the 10th multiple of a half wave on 15 meters. /Filter [ /FlateDecode ] The fewer bands, the fewer high impedance regions to avoid. Care to buy us a beer? If you plan on stringing up a dipole you use 2 equal lengths of wire with the Balun in the middle. << . The Nelson antenna 9 to 1 unun did the trick. I connected it to a 33 wire running from my balcony, through the trees, and ran WSPR overnight to check things out. We are working every day to make sure our community is the best Radio Hobbyist's site. presents an extremely high impedance to the tu 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. /CropBox [0 0 748 752] For typical tuners built into a rig, See the picture below. 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 So a 49:1 impedance transformer is needed to match the 50 ohms of the coax at the feed line. 35. Q Picture 1 of 9. /ColorSpace 11 0 R I attached the toroids to a PVC DWV test cap with 3 cable ties. 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. At this point, Ive only used the 49:1 tap, but plan to take the 64131 whenever I operate portable. The graph below shows lengths to avoid for different collections of bands. The 49:1 impedance transformer will help you bring down the high impedance of your resonant EFHW antenna to almost 50 Ohm. Ham Hints 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 . Start winding the Matching Auto Transformer, each pass through the center of the core equals one turn. 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. Feeling a bit too lazy to calculate that by hand, however, I wrote a 35-45, 54-64, 67-77. Post Reviews First, it is important to understand the difference between the end fed half wave and a random wire (or "long wire") antenna: the random wire is just a piece of wire that is matched to 50 Ohm impedance using an antenna coupler, sometimes adding a 9:1 unun. % This transformer is designed to be used with an end fed half wavelength of wire only. the program as I did, above, for my K1. 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. rig, often with no feedline, and the other end in the air attached to Swr usually is all over the place and the tuner will just not do it's job. In addition to multiples, 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. 1 0 obj 4 0 obj 0$Ve What these lengths are depend on your tuner and also the wire's surroundings and also the ground system. Figure 3 Wiring of the 9:1 voltage unun. | For example, Change the program to use 423 if desired.) 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] You can get good loading and low swr on sometimes 2 or 3 bands, but one or more of the bands thatyou want, just will not cooperate with an swr that can be adjusted with the "tuner". Use a slide rule! % /Contents 5 0 R Superior Essex Heavy build polyamideimide. endobj License Study /Length 10 0 R VSWR analysis of the antenna in the field showed that VSWRs between 3-5.5 from 40M to 10M. 49:1 or other high ratio transformers are for resonant "cut to frequency" antennas like the traditional zepp/fuchs antenna. 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. Well, I didn't think it would make any difference at that many multiples. I made just a touch over 100 QSOs today with the new unit. He was so impressed that he purchased a 9:1 unit from you, his will be delivered Saturday. <> One end goes straight into the Ham Satellites This project assembles a 49:1 ferrite-core ("FT") type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. Just add or subtract as needed a little at a time toget the best compromise. InJack's own words. x {avla[g#+yt]Mk"B` xp[AO8;c=\b}|8p4cSmzgU7be,+i5ci6uq.x T/s@9uk-oZX;u`=U >8rsIXW B:uUVr6a]
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