google_ad_height = 600; 2. IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. Electronics Use with other lengths can potentially damage the transformer depending on power level in use. Start winding the Matching Auto Transformer, each pass through the center of the core equals one turn. random wire should use 423/f. An end fed half wave antenna is one of a specific length depending on the frequency that it is to be used on, for example, an end fed half wave antenna for 80 meters is about 130 long. The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. The matching unit The impedance at the end of a half wave antenna is somewhere between 2000-5000 Ohms. 20/40/17m. Hertz Antenna" shows in line 2 of the table that a similarly installed Random wire lengths you should and should not use! STORE A 9:1 unun is a transformer that reduces the impedance at the input by a factor of 9. Hi guys,not really hfu related,but I tought I might ask here as I have my account. I use this 8010 EFHW at home, too. << 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. Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth. There probably should be some holes for ventilation. 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. The 9:1 may work best with that length wire and a tuner, but some say that length is undesirable for the hf HAM bands. When on the trail, at Field Day, or whenever a good antenna is An UNUN is needed to match the high impedance of an end fed antenna (2k-4k ohms range). /Height 752 The most important length is one that is non-resonant on any band. I won't bore you with all that so the first portion of this still only shows up to the 4th multiple. 6 0 obj Vhf and Up Re: 9:1 or 49:1 unun for end-fed long/random wire? I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. Picture Information. The trick, therefore, is either shown in the column e. var sc_project=8077274; >> Part List: Here Is a 250 Watt Home-Brew That I Made In about an Hour. A 49:1 would match 50 ohms to about 2,450 ohms and a 64:1 matches to 3,200 ohms, typical of a 1/2 wave end fed. Enclosure Height: 5.000 in. Using a 49:1 transformer shoot for the best 50 match @ appx 2450 load over your working frequency bands. Picture 1 of 9. wire is at least 1/4 wavelength. You also A so-called random wire antenna is an end fed antenna. 3 0 obj (Also check out AB3AP'Swebsite and say thanks for sharing his skills. 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. The 30 day return period lapsed before I could get the antenna deployed to test it. This project assembles a 49:1 ferrite-core ("FT") type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. endobj Here's a list of recommended lengths of wire to use with a 9:1 unun. This article explains why the use of mix 43 for HF applications is almost always a mistake. END FED "RANDOM WIRE" HF DIPOLE 9:1 ANTENNA RELACEMENT ELEMENT ONLY $28.99 Save up to 6% when you buy more. endstream endobj startxref EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! It is not a good choice for working lower bands from a too short wire, that is, if you have cut your wire to a 20m halfwave, it ain't much punkin' for 40m, 80m, or 160m. https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. Jack, VE3EED, hopefully has solved a major headache we all have when we attempt to go thru the trial and error and frustration with getting the random wire to work where WE want it to work. X:nzf4p:t;r }~_HOZcX:^$* J^XZuu|"nX/Wkw0hA>y1(z2+v_Xzu[/:^$*m*>hk_:+c{ Super Bullet Features: - Uses proprietary broadband impedance transformer design for maximum bandwidth with SWR < 2 from 1.8-61 MHz for 1500 Watt model and 1.8-30 MHz for 3000 watt model 40-10m with a 49:1 Unun. 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. Thus a 1/4 wave for 20m@16ft, 40m@33ft as examples are not going to work. is helpful if you're in a hurry to get on the air, read up on the topic . <>/Metadata 239 0 R/ViewerPreferences 240 0 R>> The length should be calculated based on the lowest frequency to be worked. 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 . SEARCH << << This Balun Designs unit is replacing an MFj 1982 HP EFHW balun that was DOA when it arrived last May. 7 0 obj and experiment. 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 . >> /Kids [ 4 0 R ] They just saved you and I loads of time and frustration. /Type /XObject /Name /Im0 It's an efficient way to get all the multiples Antenna Design 27.00 (27.00/Unit) Free Postage. Jack, VE3EED - SK. 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 actually did this first and before the connector was bolted to the box. Use a slide rule! Coverutilizes integralneoprene gasket for weatherproof integrity. 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 do you use a 1:1, 9:1 or a 49:1 balun? hb```YloD@(aKI V!}g@~}%Q/[[~_=Wy-:O)x[~hs/~SGeG _QE C6q %r SO-239 connectors are silver plated with Teflon insulation. I have found this calculation to work well, however it depends on many factors such as wire used, location etc. wire lengths less than 1/4 wavelength of the lowest desired frequency 8 0 obj Balun Designs. 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. The key is you want to stay at least 1/2w long but not near 3/4w for any band of interest. So for 80 meters (say 3.525 MHz) this gives you about 133' of wire. Antenna") is an 84' long end fed and a 17' long counterpoise (6.5' for 20m). Powered by BigCommerce. I have not done this yet. Windings are inserted into Teflon tubes increasingtotal breakdown to 10,000 volts. Wire-Lengths-for-9-1-ununs.pdf Created Date: 12/12/2022 11:20:42 AM . The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. 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. /Count 1 The 49:1 impedance transformer will help you bring down the high impedance of your resonant EFHW antenna to almost 50 Ohm. Because I'm more visually oriented I then plotted the many overlapping "red zones" and ended up with the page at: For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. //-->, The "Best" Random Wire Antenna Lengths 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. all US ham bands.