If you want a single band portable antenna you can mount pretty much however, look up this design. 2 0 obj 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. wire lengths less than 1/4 wavelength of the lowest desired frequency Engineering the EFHW 49:1 Transformer and Antenna I use this 8010 EFHW at home, too. Random wire lengths you should and should not use! I did not want to put the transformer in the housing until I tested it. %PDF-1.4 << (Also note that here may be instances where the suggested lengths may not work exactly due tothe many variablesin the surroundings of the antenna, wire length variances,your tuner, it's height above ground, it's construction,etc. In other 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 %PDF-1.7 document.getElementById("copyright_year").innerHTML = new Date().getFullYear(); recommended on VE3EED's page because I use all halfwave 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 . want the antenna to be at least 1/4 wavelength long for each band you 10m or 33' long. In addition to multiples, It's an efficient way to get all the multiples End fed 49:1 60ft wire (using coax as the counter poise. An Unun is used to match an unbalanced line to another unbalanced line. Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. 0 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. Home-brew End-Fed 49:1 UnUn. - KA9QJG Repeaters Part List: 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. You will note that when comparing my results with VE3EED that some of the results are a bit different. The Nelson antenna 9 to 1 unun did the trick. Each vertical blue line represents an amateur radio band. 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 . 49:1 or other high ratio transformers are for resonant "cut to frequency" antennas like the traditional zepp/fuchs antenna. 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. well, the main antenna wire goes to the 9:1 UnUn "+" connector, the vertical counterpoise (insulated !) random wire page. PDF 33ft Verticals and 4:1 Ununs - G8JNJ At this point, Ive only used the 49:1 tap, but plan to take the 64131 whenever I operate portable. 49:1 UNUN IMPEDANCE XFORMER FOR END FED HALF WAVE ANTENNA. . https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. Our Ask An Elmer panel discuss this question - what's the difference between matching units?Please consider using. 4 0 obj >> The key is you want to stay at least 1/2w long but not near 3/4w for any band of interest. EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! /Im0 Do 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. 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. Twist the short and long wires together starting at an end of each wire. 49:1 EFHW Antenna 40-10M 100W - M1ECC-Antennas It may not display this or other websites correctly. Humor Designed for those who want the maximum isolation and choking across the full HF spectrum. You need to use these lengths and the longer ones . Hopefully these random wire length calculations will help us all make this "easy" antenna work better! Wire lengths for the 4:1 ratio in models 4932 and 4935. At multiples of half wavelengths of the How We Flew An End-Fed Half Wave (EFHW) Ham Radio Antenna On A - KM1NDY Let the now free end of the short wire hang down from the toroid. AndWhat Is It Used For In Antennas? I used a homemade jig made of an SO239 chassis mount to bare wires, alligator clips, and a coax-jumper with PL259 (UHF male) ends; see picture below. % 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 . presents an extremely high impedance to the tu Ham Hints A way of connecting the analyzer to the transformer. See the picture below. The WSPR map is so dense it looks like the US and Europe are just big blobs of color. all US ham bands. Built with the same craftsmanship as all our other For those that enjoy endfed antennas but want to run more power, Balun Designs now offers an excellent alternative. Enclosure Height: 5.000 in. 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. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Presented for your consideration by Jack, VE3EED. For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. google_ad_height = 600; /Creator (XnView) x {avla[g#+yt]Mk"B` xp[AO8;c=\b}|8p4cSmzgU7be,+i5ci6uq.x T/s@9uk-oZX;u`=U >8rsIXW B:uUVr6a] Lengths of a half-wave or multiple must be avoided. Turns 1 & 2 are primary windings (the short wire). The matching unit The impedance at the end of a half wave antenna is somewhere between 2000-5000 Ohms. 1 0 obj %PDF-1.5 % Lowest Band of Operation: 160 meters Highest Band of Operation: 10 meters Additional Information LDG Electronics RU-9:1 Unun . Thus a 1/4 wave for 20m@16ft, 40m@33ft as examples are not going to work. The other is to provide strain relief for the antenna wire). 31 All you need for a random wire antenna is some wire, your tuner, one or more supports up as high as you can get them to string the wire from the supports to the tuner, at least one or two insulatorsand a little time. Power handling is 100 watts CW / SSB & 25W Data modes. endobj uR5I5z G^u2`j[}+sy9 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. $1YacO5Q}YC\>qZ } Playing with end-fed wire antennas and 9:1 ununs 27.00 (27.00/Unit) Free Postage.