40-30-20-15m bands for my 4 band Elecraft K1 qrp rig. Here Is a 250 Watt Home-Brew That I Made In about an Hour. For typical tuners built into a rig, 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 . /Subtype /Image 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! 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 "Can you please recommend schematics that are designed to tune setups like these? Because I had some spare Cu-Wire I wound another 1:49 Unun on a smaller FT-140-43 toroid and tried different capacitors between feedline and ground (to compensate for the 10m band). <>>> 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. Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands. /XObject << /Im0 9 0 R >> >> Best SWR was . See the picture below. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. End fed 49:1 60ft wire (using coax as the counter poise. (The numbers aboveare a great start, thanks to Jack and Mike! 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. stream Thus a 1/4 wave for 20m@16ft, 40m@33ft as examples are not going to work. 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. << We are working every day to make sure our community is the best Radio Hobbyist's site. 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. << 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. /BitsPerComponent 8 So, having nothing better to do one day, I re-did the calculations going out to 500 feet. %PDF-1.7 Jack, VE3EED, used center frequencies of thebands described in the article above, and I thought it would be nice to use band edges. /* Ad banner 160 x 600 */ Just an FYI that I thought you might be interested in. BUILD INSTRUCTIONS FOR 49:1 UNUN IMPEDEDENCE TRANSFORMER: WX1MAR and I brought the DIY 49:1 unun with a borrowed antenna radiator wire cut for 20M half-wavelength to Ashland State Park K-2417 in Massachusetts for a Parks-on-the-Air (POTA) activation. Moving the pot up and down gives a feel for the SWR versus antenna impedance sensitivity. This antenna, which works on 10, 15, 20, and 40 meters, has a very high impedance of around 2,500 Ohms. (Also check out AB3AP'Swebsite and say thanks for sharing his skills. Proudly powered by WordPress 2 eyehooks with washers and nuts (I used #8 diameter, but size is up to you.) Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. are blocked out because an antenna should be at least that long. Thank you so much for such a great product! you're using different ham bands than in these examples, modify and rerun (QST, Oct 1926, "The Length of the endobj However, the list has been revised and is good for wires as long as 500 feet. 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.). 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. well, the main antenna wire goes to the 9:1 UnUn "+" connector, the vertical counterpoise (insulated !) and experiment. The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. AndWhat Is It Used For In Antennas? Theme: Newsup by Themeansar. << An Unun is used to match an unbalanced line to another unbalanced line. 75/80 METER RESONATOR KIT FOR THE UJM-EFHW-40-10 200W 40-10m ANTENNA These dimensions were derived from modelling the antenna in EZNEC. endobj 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 following wire connections do not need to be made in the order I described. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Theme designed by Papathemes. 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. 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. 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. This design is excellent for matching both long and short length wire antennas for multiband use. We recently found some good information about random wire lengths that you should and should not use. wire is at least 1/4 wavelength. Some of these numbers are too close to squeeze in between them. Site Map Start winding the Matching Auto Transformer, each pass through the center of the core equals one turn. When you're antenna (or radial) length's an odd multiple of the operating freq, you may not need a balun or even a transmatch. endobj Support The Site It's an efficient way to get all the multiples Palomar Engineers employs a dual core matching system that offers wide bandwidth (1-61 MHz), 500 watt PEP rating, and a connection for a counterpoise or ground if desired. 748 0 0 752 0 0 cm The QRP End-Fed Half-Wave Antenna 49:1 Transformer Building a great impedance transformer for Ham Radio end-fed wire antennas. This Balun Designs unit is replacing an MFj 1982 HP EFHW balun that was DOA when it arrived last May. Presented for your consideration by Jack, VE3EED. The counterpoise wire, This transformer is designed to be used with an end fed, Approx. it is easy to pack and easy to install. google_ad_width = 160; 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. a more capable tuner - see AA5TB's This is not exactly a 1/2 wavelength in free space, but works for wire as it has a different velocity factor than "air". 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. 1 0 obj Hi guys,not really hfu related,but I tought I might ask here as I have my account. 27.00 (27.00/Unit) Free Postage. (Originally published February 22, 2021). Ham Radio Videos! 80m up, W3EDP's 84' antenna, 17' counterpoise is probably the way to go. If the choices are. results. For instance, to work 40m be sure the antenna is at least 10m or 33' long. used by hams for dipole lengths. the program as I did, above, for my K1. 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. The 49:1 End Fed Half Wave Antenna is very popular choice for home & field use, Ideal for limited space and stealth applications. This homebrew 49:1 impedance transformer is the heart of any EFHW antenna you will build, most of the time. 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. He used 300 ohm twin-lead and a 4:1 UNUN, with a 1:1 current choke between the UNUN and the coax to the tuner and transceiver: The full-size "flimsy" (ref. (Center fed is so appealing because you avoid this.). If you want all the bands from I will also find some sort of heat resistant packing material to help hold the transformer in place. Again, the bands are USA, so change them The graph below shows lengths to avoid for different collections of bands. 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. (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. 7 0 obj Let the now free end of the short wire hang down from the toroid. The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. 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. endobj The idea Both were on 20 meters at 97 watts, Icom 7300. Coverutilizes integralneoprene gasket for weatherproof integrity. Just add or subtract as needed a little at a time toget the best compromise. One is for the top of the box so that it can be hung up. About Hamuniverse Using a 49:1 transformer shoot for the best 50 match @ appx 2450 load over your working frequency bands. /ModDate (D:20221212112042) However, the radio didn't tune up very well on 15 meters. An UNUN is needed to match the high impedance of an end fed antenna (2k-4k ohms range). << wire lengths less than 1/4 wavelength of the lowest desired frequency Use only the white gaps for your antenna lengths, and if Update guys:made the unun,the antenna was extended to about 37m length,and I added a counterpoise which is about 10m.The whole thing is much higher in the air,compared to where it was before. Antenna") is an 84' long end fed and a 17' long counterpoise (6.5' for 20m). For example, Powered by BigCommerce. This calculates to 4.2 m or 14 ft for an 80m end-fed. hbbd```b``^ "Cs;D2 I*`0D;+EVUHy`qml0{YVw`b0i DvkAh |"w I2% ?W%@Fg`` 6 3 to31 MHz - up to 1kW intermittent (50% duty cycle). 25 0 obj <> endobj for your country and favorite modes of operation. ", KiwiSDR Online Radio - 500 ft Northeast Beverage, KiwiSDR Online Radio - 400 ft South Beverage, KiwiSDR Online Radio - 10/11m dipole up 20 meters high. So for example 80m could range in length from 120 to 133 feet. This is a 4:1 Current Balun.That means it can match a 200ohm antenna to a 50 feed line. For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. /ColorSpace 11 0 R 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. I wrote a small C program that does just what Jack did, butI used the band edges. EFHW unun Resonant Long Wire 49:1 Transformer With 67' Antenna Wire. 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. stream VSWR analysis of the antenna in the field showed that VSWRs between 3-5.5 from 40M to 10M. 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- ?7{*. To summarise the results WRT to reference antenna consisting of 30ft wire vertical fed with auto- Longer wire is always more Winding 1:64 Matching Auto Transformer on the FT240-43 core. 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. Hopefully these random wire length calculations will help us all make this "easy" antenna work better! /Width 748 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. . Free Postage. End fed 9:1 58ft wire and 17ft counterpose wire touching ground. Alternate connectors and Mounting Options are available in the. Some important and helpful references I used for this work: https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. bands as possible. %PDF-1.5 I plotted the results for the U.S. CW band edges for use with my4 band Elecraft K1 qrp rig. Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. As typically Code Practice SEARCH 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. Each winding is counted when the wire enters through the center hole of the toroid. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Repeater Basics V#X~[Z?\ZcX:-Y?&Y?IqTnayZ{jTZOub}=UTWu1G>o.,RaT c=W>:sECXTkc=X /Height 752 random wire page. 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. After winding #2 is made and extends down the backside of the toroid, untwist the wires. Usually any wire length that is non resonant on the band or bands desired will work with the 4:1 ratio. 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? Picture Information. Work all bands from 80 through 10 on it. 40-10m with a 49:1 Unun. 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. 73, Even easier than https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. Multiples are on C and . 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. recommended on VE3EED's page because I use all halfwave Drill out holes in the designated bottom of the electrical junction box for the SO239 chassis mount. 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.). Reading Room 4 0 obj x@ The trick, therefore, is either Tools Typically unbalanced = 50/75 ohms too unbalanced = 450/675 ohms. Repeater Builders The Short Answer Would Be That an UnUn Is a UN balanced to UN balancedmatching transformer. Tune Around! 10m or 33' long. endobj presents an extremely high impedance to the tu So I just wanna say thank-you!! Wire-Lengths-for-9-1-ununs.pdf Created Date: 12/12/2022 11:20:42 AM . I used the RigExpert Zoom AA-55 to test VSWR of the 49:1 unun impedance transformer. 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] The WorldwideDX Radio Forum was originally established in 2001. At multiples of half wavelengths of the Save program output in file named 'f', and use Hertz Antenna" shows in line 2 of the table that a similarly installed Post Reviews /Type /Pages If you want a single band portable antenna you can mount pretty much however, look up this design. google_ad_height = 600; shown in the column e. var sc_project=8077274; 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". 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. 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. Wire lengths for the 4:1 ratio in models 4932 and 4935. It uses an FT140-43 or FT240-43 toroid in a 49:1 impedance matching unit at the base and a 110 micro Henry (H) coil to act as a loading coil for 80m and a choke to stop higher frequencies using the last 2m of wire. Experimenting by slightly changing the wire length (+ or-) is encouraged to provide best overall performance. Lengths to avoid are not always the same as 31 var sc_security="1df091cc". %PDF-1.5 % random wire should use 423/f. << Antenna Design The major point of this message is to tell you that approximately 20 minutes after I connected the balun unit to the antenna, I made contact with a gentleman in Italy-my first European contact!! 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.

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