plan to use. wire is at least 1/4 wavelength. Ham Satellites endobj We recently found some good information about random wire lengths that you should and should not use. Start winding the toroid with the twisted wires at loop #1 (see schematic below). Lengths to avoid are not always the same as are blocked out because an antenna should be at least that long. 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. Balun Designs. /Length 10 0 R UJM-49-1 $56.99 Save up to 6% when you buy more. 2 0 obj I have not done this yet. << Free Postage. . /CreationDate (D:20221212112042) There are numerous configurations available online that will accomplish this on multiple bands (Google search "end fed half wave antennas"). The QRP End-Fed Half-Wave Antenna 49:1 Transformer Building a great impedance transformer for Ham Radio end-fed wire antennas. /Length 6 0 R wire lengths less than 1/4 wavelength of the lowest desired frequency Code Practice If the choices are. (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. Anyway, an old friend mentioned 'MyAntenna.com' but they were closed for the summer. google_ad_width = 160; The "9:1 UNUN" are for random length wire antennas fed at the end. Support The Site InJack's own words. Theme designed by Papathemes. The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. 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. Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. Use only the white gaps for your antenna lengths, and if The kit includes the parts needed to construct a 49:1 impedance matching network, which will transform the impedance to 50 Ohms, which will suit most transceivers. A VSWR sweep of the unun after adding a 100pF capacitor shows an SWR <5:1 from 160M to 10M. This calculates to 4.2 m or 14 ft for an 80m end-fed. I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. "Here's the word on random-wire antennae.". I actually did this first and before the connector was bolted to the box. This is the latest and greatest transformer design for End Fed Half Wave (EFHW) antennas. 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. That's it in a nutshell..or is it? IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. Many hams have tried till they are blue in the face to install the random wire antenna that works on most; if not all of the HF bands with terrible results. endobj About Batteries 35-43, 49-63, 70-85. wire to the UnUn "-" connector and then down to ground there it connects with the two other wires but neither the counterpoise nor the two other wires are connected to ground. So, having nothing better to do one day, I re-did the calculations going out to 500 feet. This article details the construction of the transformer. Weight: 0.380 lbs. . For those that enjoy the LNR and Hy Endfed antennas, but want to run more power, 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, ttaching a counterpoise wire to the common point of the auto-transformer, provides the antenna radiator something to push against rather than the coax shield. Jack, VE3EED - SK. One end goes straight into the Twist the short and long wires together starting at an end of each wire. An UNUN is needed to match the high impedance of an end fed antenna (2k-4k ohms range). the C code, in Matlab or Octave get a plot by simply putting the bands you're intested in in a vector like the example below, by typing. That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . %PDF-1.7 Electronics <> %PDF-1.5 %PDF-1.5 % /Type /Catalog << Presented for your consideration by Jack, VE3EED. (wlSR9dJ_x%+VHX4FRr 3>;g^x%g'wkJu,i~#Q"2|WGf[!_m]#&1$)R.{--" 'dGO;=_B$T}". Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands. 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. 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. for your country and favorite modes of operation. The WSPR map is so dense it looks like the US and Europe are just big blobs of color. We do not encourage any radio operations contrary to regulations. endobj 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. This design is excellent for matching both long and short length wire antennas for multiband use. A small ring terminal for 14ga wire that fits these screws would be helpful too. Bullet 50:450 (9:1) HF Unun, 1.8-61 MHz, 1500 Watts, End Fed Antennas. Part List: To DB's point of a single band antenna, this 49:1 transformer is a good choice for a single band matcher. 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. 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. 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. Stacked coreswithwinding configured as 49:1auto transformer. shown in the column e. var sc_project=8077274; 4 0 obj /MediaBox [0 0 748 752] , This is a partial reprint (with permission) of an excellent series of articles published by KV5R 49:1 End Fed Half Wave Antenna 40-10M 100W Version Bands of operation 40,20,15 & 10m using 67 feet of our UV, Ozone resistant Antenna wire. 1 X FT240-43 Ferrite Toroid Core 43 Material(Mouser Electronics), 1 X SO-239 UHF PANEL JACK S/CUP SO-239(Mouser Electronics), No. Therefore, we came up with the following numbers to avoid (IN FEET): These lengths in the table beloware the culprits that cause all of the trouble when using random lengths. 80m up, W3EDP's 84' antenna, 17' counterpoise is probably the way to go. all US ham bands. Here are the final numbers (in my opinion) in green below that would be good for a long-wire antenna: (You may want to make a note of them), REVISED: 29 35.5 41 58 71 84 107 119 148 203 347 407 423, REVISION NOTE: We had a note from James, KB5YN, pointing out that one of my so-called GOOD numbers was 220 feet. So I just wanna say thank-you!! answers on D - one setting. (The numbers aboveare a great start, thanks to Jack and Mike! 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 . 33 ft #18 insulated copper wire (20m half wave), Counterpoise: 1 meter coax (0.05 x wavelength) connected between 64131 and Balun Designs 1115d Isolation /Choking balun, If you would like to use high power up to legal limit with a single end fed wire antenna (not necessarily a half wave) consider using our. you're using different ham bands than in these examples, modify and rerun Lengths of a half-wave or multiple must be avoided. I won't bore you with all that so the first portion of this still only shows up to the 4th multiple. An Unun is used to match an unbalanced line to another unbalanced line. So you have the freq range of interest and the total length of the wire, figuring out wich balun will be a better match for 50ohm coax should be easy. /ModDate (D:20221212112042) frequencies for your country or favorite modes. 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. google_ad_slot = "1982258389"; It is important to use a counterpoise. x 4 in. 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. EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! Here I show finalizing the antenna, getting it in the air, and run. A success! 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). I made one without doing this and it didn't work so well. 3 0 obj 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. 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. Vacation Closure - See Homepage for Next Availability. Notice from column f that there is no length giving low impendance for 9:1 UnUn End Fed Long Wire Lengths - Pretty Simple. , Most matching problems occur when the antenna system Some important and helpful references I used for this work: https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. 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. stream . Some of these numbers are too close to squeeze in between them. (Also check out AB3AP'Swebsite and say thanks for sharing his skills. Hi guys,not really hfu related,but I tought I might ask here as I have my account. Here Is a 250 Watt Home-Brew That I Made In about an Hour. 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".