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. /Height 752 The QRP End-Fed Half-Wave Antenna 49:1 Transformer Building a great impedance transformer for Ham Radio end-fed wire antennas. endobj My homemade 49:1 EFWH with a 60 wire (cut for 40M) would do just fine! 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! 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. One end goes straight into the /MediaBox [0 0 748 752] 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. When used with the stated Balun Designsis now offering a low power alternative for those who want to use an End Fed Half Wave for portable or temporary installations. If the choices are. The bandwidth where SWR was below 2:1 was about one MHz. Windings are inserted into Teflon tubes increasingtotal breakdown to 10,000 volts. This was 9m vertically metres up a fishing pole and then about 5.8m out. Meet 'Balun One Nine', a small, cost-effective balun. HF & Shortwave 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. 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 This calculates to 4.2 m or 14 ft for an 80m end-fed. . 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. This transformer converts the impedance at the end . << 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 . 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. (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. << For instance, to work 40m be sure the antenna is at least 6 0 obj thank you. Tweak the antenna length if necessary and then maybe adjust the turns ratio again. %PDF-1.5 Wire lengths for the 4:1 ratio in models 4932 and 4935. PVC Junction Box(Home Depot), 1 x 1/2 in. 1863 1.49 swr 3915 2.50 7200 1.80 14.332 1.29 18.130 1.07 21.300 1.40 24.950 1.30 28.400 1.37 This is a great antenna that is . It is important to use a counterpoise. So for example 80m could range in length from 120 to 133 feet. 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. Just add or subtract as needed a little at a time to get the best compromise. The counterpoise wire, This transformer is designed to be used with an end fed, Approx. >> /Subtype /Image For a better experience, please enable JavaScript in your browser before proceeding. 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. I will also find some sort of heat resistant packing material to help hold the transformer in place. Click to enlarge. Moving the pot up and down gives a feel for the SWR versus antenna impedance sensitivity. google_ad_height = 600; Each vertical blue line represents an amateur radio band. Advertising Info 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. End fed 49:1 60ft wire (using coax as the counter poise. 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. google_ad_client = "ca-pub-9377297764300878"; 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. Just an FYI that I thought you might be interested in. document.getElementById("copyright_year").innerHTML = new Date().getFullYear(); << In total 29 contacts were made from British Columbia to Texas to Florida in 40 minutes on 20M. Liquidtight NM 90-Degree Connector(Home Depot). Ask Elmer Usually any wire length that is non resonant on the band or bands desired will work with the 4:1 ratio. It will be good for 15m, and 10m. 10m or 33' long. this recommended on VE3EED's page because I use all halfwave This will be for an eyehook in order to provide strain relief for the radiator wire. 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. Lengths of a half-wave or multiple must be avoided. 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. The WSPR map is so dense it looks like the US and Europe are just big blobs of color. << Continue on winding the long wire through the toroid to complete loops 3 through 14 as shown in the schematic below. <> 74 0 obj <>stream Product Reviews SSTV 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. 1 0 obj Antenna Safety! Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth. Alternate connectors and Mounting Options are available in the. The fewer bands, the fewer high impedance regions to avoid. is helpful if you're in a hurry to get on the air, read up on the topic endobj 49:1 UNUN IMPEDANCE XFORMER FOR END FED HALF WAVE ANTENNA. Thanks for your answer,I will probably go with the 9:1 then. You can add your own wire or get the complete product from this link EFLW-3K antennas. 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. I have never tried to transmit through it, but it proved the optimal ratio for receiving with my setup. 0 31 Our Ask An Elmer panel discuss this question - what's the difference between matching units?Please consider using. This undesired reflection of RF power back toward the transceiver is identified as a high voltage standing wave ratio (VSWR or SWR). (The numbers aboveare a great start, thanks to Jack and Mike! I plotted the results for the U.S. CW band edges for use with my4 band Elecraft K1 qrp rig. endobj 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. 0$Ve Ham Satellites Jack, VE3EED, used center frequencies of thebands described in the article above, and I thought it would be nice to use band edges. I'll get a 9:1 unun,and use a suggested random wire length to avoid half-wave and it's multiples then,that sounds like the best things I can get out of this setup. 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). They just saved you and I loads of time and frustration. We do not encourage any radio operations contrary to regulations. I made just a touch over 100 QSOs today with the new unit. %PDF-1.5 % wire lengths less than 1/4 wavelength of the lowest desired frequency 1 0 obj What these lengths are depend on your tuner and also the wire's surroundings and also the ground system. An UNUN is needed to match the high impedance of an end fed antenna (2k-4k ohms range). 9:1 or 49:1 unun for end-fed long/random wire? A 9:1 unun is a transformer that reduces the impedance at the input by a factor of 9. Use only the white gaps for your antenna lengths, and if Typically unbalanced = 50/75 ohms too unbalanced = 450/675 ohms. The short piece is for the primary winding of the transformer, and the long piece is for the secondary winding of the transformer. unavailable, a random wire can save the day, but it is important to 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] 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. %PDF-1.7 This transformer is designed to be used with an end fed half wavelength of wire only. Support The Site 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. it is easy to pack and easy to install. Post Reviews Here's a list of recommended lengths of wire to use with a 9:1 unun. You'll want to have that wire up as high as you can get.. I use this 8010 EFHW at home, too. These are sometimes known as a Magnetic Longwire Balun. Again, the bands are USA, so change them 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. This is a followup video to #344 where I assembled the 49:1 UNUN kit from HF-Kits / ARRL. The magic lengths to use with the End Fed longwire is 29, 35.5, 41, 58, 71 and 84 feet I use a 29 foot wire with my PackTenna 9:1 balun for 40m-10m and then add a 28 foot length for better coverage on 80m when needed. I did not want to put the transformer in the housing until I tested it. You also SEARCH bands you're intested in in a vector like the example below, by typing. Designed for those who want the maximum isolation and choking across the full HF spectrum. NEMA rated 4x marine grade junction box for outdoor installations. The idea 1 0 obj About Batteries frequencies for your country or favorite modes. (Center fed is so appealing because you avoid this.). Turns 1 & 2 are primary windings (the short wire). In stock . UJM-49-1 $56.99 Save up to 6% when you buy more. 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. << ", KiwiSDR Online Radio - 500 ft Northeast Beverage, KiwiSDR Online Radio - 400 ft South Beverage, KiwiSDR Online Radio - 10/11m dipole up 20 meters high. google_ad_width = 160; Even better would be shortening to 53'. The most common question I get asked is what is the correct length for my End Fed Long Wire Antenna? Save program output in file named 'f', and use /Kids [ 4 0 R ] Just add or subtract as needed a little at a time toget the best compromise.