Antenna Design I won't bore you with all that so the first portion of this still only shows up to the 4th multiple. 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 A Balun is used to match a balanced line to an unbalanced line. 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. Wire lengths for the 4:1 ratio in models 4932 and 4935. Repeater Builders (Originally published February 22, 2021). << 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! The beauty of the halfwave antenna is it's a complete antenna in the sense it needs no counterpoise. 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 . 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. 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). JC[ d8O[UKKQ{yZ{G 'Upno_*~8uo a@G`' zxUHXW&`}mEp`?i0 oE:N0-/t"t.-? Superior Essex Heavy build polyamideimide. 0 END FED "RANDOM WIRE" HF DIPOLE 9:1 ANTENNA RELACEMENT ELEMENT ONLY $28.99 Save up to 6% when you buy more. So for 80 meters (say 3.525 MHz) this gives you about 133' of wire. endobj UNUN 9:1 or 4:1- 3kW ICAS This is is dual 9:1 and 4:1 UNUN used for popular "non-resonant" length END FED wire antennas or verticals like 27 or 43 feet. InJack's own words. /Filter [ /FlateDecode ] $119.95. 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. We hoisted the free end of the antenna wire approximately 30 feet into a tree. | N4UJW. Power handling is 100 watts CW / SSB & 25W Data modes. This transformer converts the impedance at the end . Theme designed by Papathemes. transmit frequency the impedance is so high that tuners in most rigs endstream endobj startxref . endobj My homemade 49:1 EFWH with a 60 wire (cut for 40M) would do just fine! Our Ask An Elmer panel discuss this question - what's the difference between matching units?Please consider using. . Q So is an essential piece of gear to have. endobj The length should be calculated based on the lowest frequency to be worked. 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. =======================, 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: Continue twisting the entire length of the short wire. Theme: Newsup by Themeansar. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. A few more comments about this 49:1 autotransformer EFHW design. 2 0 obj So, having nothing better to do one day, I re-did the calculations going out to 500 feet. well, the main antenna wire goes to the 9:1 UnUn "+" connector, the vertical counterpoise (insulated !) /Parent 3 0 R q 9:1 or 49:1 unun for end-fed long/random wire? AndWhat Is It Used For In Antennas? 9:1 Unun 1.5-54MHz 2kW 9132S. << If you plan on stringing up a dipole you use 2 equal lengths of wire with the Balun in the middle. "Can you please recommend schematics that are designed to tune setups like these? Weight: 0.380 lbs. %%EOF In another life, I could have been a telephone engineer. Presented for your consideration by Jack, VE3EED. /Name /Im0 End fed 9:1 58ft wire and 17ft counterpose wire touching ground. google_ad_height = 600; What these lengths are depend on your tuner and also the wire's surroundings and also the ground system. Figure 2 Schematic of the 9:1 voltage unun . That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . End fed 49:1 60ft wire (using coax as the counter poise. The QRP End-Fed Half-Wave Antenna 49:1 Transformer Building a great impedance transformer for Ham Radio end-fed wire antennas. 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. 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. Site Map So those are the numbers above thatwe have to stay as far away from as possible when building a long-wire antenna. 31 However, the radio didn't tune up very well on 15 meters. Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. Antenna") is an 84' long end fed and a 17' long counterpoise (6.5' for 20m). endobj The "9:1 UNUN" are for random length wire antennas fed at the end. answers on D - one setting. Tune Around! are blocked out because an antenna should be at least that long. (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. unavailable, a random wire can save the day, but it is important to The other is to provide strain relief for the antenna wire). Use only the white gaps for your antenna lengths, and if Each vertical blue line represents an amateur radio band. /Type /Catalog Computer Help A small ring terminal for 14ga wire that fits these screws would be helpful too. These are sometimes known as a Magnetic Longwire Balun. You can take one of these 49:1 transformers and use the 468/freq (Mhz) formula to calculate the length you need in feet. it is easy to pack and easy to install. 5 0 obj var sc_invisible=1; Swr usually is all over the place and the tuner will just not do it's job. 3 0 obj I will also find some sort of heat resistant packing material to help hold the transformer in place. NEMA rated 4x marine grade junction box for outdoor installations. you're using different ham bands than in these examples, modify and rerun 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 . 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. which got me thinking. You need to use these lengths and the longer ones . 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. 40-30-20-17. 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. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 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. 40-10m with a 49:1 Unun. This design is excellent for matching both long and short length wire antennas for multiband use. Even better would be shortening to 53'. [ /PDF /Text /ImageI ] The 30 day return period lapsed before I could get the antenna deployed to test it. EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! STORE K1S Valentines Are (Almost) Out The Door! 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. 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. 9:1 Unun EF Random Long wire matching Transformer with BNC or SO-239. When do you use a 1:1, 9:1 or a 49:1 balun? 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. 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. The fewer bands, the fewer high impedance regions to avoid. /* Ad banner 160 x 600 */ If the choices are. Technical specification : Type : 49:1 Unun Frequency : 1.8 MHz - 7.3 MHz Turns ratio: 1:7 Impedance ratio: 1:49 Input Impedance: 50 Output Impedance: 2450 Power Handling (CW/SSB/ Digital Modes) : 2Kw of peak power / DM Modes 500 watts Core Type : 3 x FT240-43 by Fair-rite Co. Wire type: Enamel copper wire 2.0 mm (AWG 12) Assembled and tested. This type of antenna is very easy to install because there is no need . The ratio doesn't need to be 49:1 2,400 ohm either, other ratios will transform to other impedance. The trick, therefore, is either Winding 1:64 Matching Auto Transformer on the FT240-43 core. Tweak the antenna length if necessary and then maybe adjust the turns ratio again. Ultimately, this housing works fine, but it is heavy and clunky.). Coverutilizes integralneoprene gasket for weatherproof integrity. Contact stream 73. JACK, VE3EED . In total 29 contacts were made from British Columbia to Texas to Florida in 40 minutes on 20M. Humor document.getElementById("copyright_year").innerHTML = new Date().getFullYear(); 73, 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. This is the latest and greatest transformer design for End Fed Half Wave (EFHW) antennas. For example, when adding a 1/4w tiger tail to a 2m ht with a halfwave for antenna will likely show no improvement at all in tx or rx strengths. 3. 74 0 obj <>stream this There probably should be some holes for ventilation. <>>> 40-30-20 . Here I show finalizing the antenna, getting it in the air, and run. for your country and favorite modes of operation. Antenna Safety! >> The short piece is for the primary winding of the transformer, and the long piece is for the secondary winding of the transformer. Best SWR was . 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. /Height 752 A success! << Start winding the toroid with the twisted wires at loop #1 (see schematic below). NOTE: Rewording the previous paragraph, if you have a capable enough <>/Metadata 239 0 R/ViewerPreferences 240 0 R>> 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 sent him the link to the 49:1 unit to get his feedback. A so-called random wire antenna is an end fed antenna. Cannon". 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. 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. One end goes straight into the Here's a list of recommended lengths of wire to use with a 9:1 unun. Ham Radio Videos! 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 . ?7{*. Generally an EFHW will be in the range of 2,000 to 5,000 ohms at the very end of the dipole when resonant. At this point, Ive only used the 49:1 tap, but plan to take the 64131 whenever I operate portable. /ColorSpace 11 0 R 2. 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. Lengths to avoid are not always the same as 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.