Just add or subtract as needed a little at a time to get the best compromise. Stacked coreswithwinding configured as 49:1auto transformer. Here Is a 250 Watt Home-Brew That I Made In about an Hour. << 22.00 + 5.00 Postage. 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. Here's a list of recommended lengths of wire to use with a 9:1 unun. Computer Help 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. Picture 1 of 9. 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. In fact, the 9:1 unun that I built is actually an autotransformer. Just add or subtract as needed a little at a time toget the best compromise. A standard recommendation (see QST, March 1936, p. 32, "An Unorthodox Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands. I made one without doing this and it didn't work so well. /Parent 3 0 R Privacy Policy . 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 . thank you. Using a 49:1 transformer shoot for the best 50 match @ appx 2450 load over your working frequency bands. The length should be calculated based on the lowest frequency to be worked. u?X`f0&/Ri;W0Tn_*TX:ug endobj I usually go with a 3.2k transformation wire winding ratio of 8:1 which is a final impedance conversion of 64:1 (50ohm * 64 = 3.2k ohm). A way of connecting the analyzer to the transformer. this Hertz Antenna" shows in line 2 of the table that a similarly installed google_ad_width = 160; 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 say run what you got and don't worry about it. See the picture below. A success! well, the main antenna wire goes to the 9:1 UnUn "+" connector, the vertical counterpoise (insulated !) At this point, Ive only used the 49:1 tap, but plan to take the 64131 whenever I operate portable. Superior Essex Heavy build polyamideimide. June 8, 2022 at 9:17 am. var sc_invisible=1; 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.). Use only the white gaps for your antenna lengths, and if The fewer bands, the fewer high impedance regions to avoid. 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. "I received my third balun from Balun Designs this afternoon. I have found this calculation to work well, however it depends on many factors such as wire used, location etc. <>/Metadata 239 0 R/ViewerPreferences 240 0 R>> 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- The WorldwideDX Radio Forum was originally established in 2001. 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. Contact Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth. used by hams for dipole lengths. 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. 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. >> 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. I'm looking forward to getting off work and hitting 40 & 20 meters again!! 35. X:nzf4p:t;r }~_HOZcX:^$* J^XZuu|"nX/Wkw0hA>y1(z2+v_Xzu[/:^$*m*>hk_:+c{ 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. Lengths to avoid are not always the same as For example, The QRP End-Fed Half-Wave Antenna 49:1 Transformer Building a great impedance transformer for Ham Radio end-fed wire antennas. Use with other lengths can potentially damage the transformer depending on power level in use. You have to stay away from a half wavelength on any frequency. One end goes straight into the While these lengths have been shown to work well on many bands, which 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. Experimenting by slightly changing the wire length (+ or-) is encouraged to provide best overall performance. << 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. IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. $119.95. (Note: I am not satisfied with this part of the project, so I will describe it here briefly. all US ham bands. Save program output in file named 'f', and use Because I'm more visually oriented I then plotted the many overlapping "red zones" and ended up with the page at: Continue twisting the entire length of the short wire. Lengths for Long-wire Antennas Jack - VE3EED Recommended lengths: 29 - 35.5 - 41 - 58 - 71 - 84 - 107 - 119 - 148 - 203 - 347 - 407 - 423 Not recommended lengths: 16 - 19 - 22 - 26 - 32 - 33 - 38 - 44 - 46 - 48 - 52 - 64 - 65 - 66 - 76 it is easy to pack and easy to install. 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. 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. I included the tools I used to analyze the transformer as well; this is only necessary if you are interested in analyzing your project. The idea One single wire, no solder connections,very simple.all the way from the tuner to the end support. 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. Both were on 20 meters at 97 watts, Icom 7300. << So those are the numbers above thatwe have to stay as far away from as possible when building a long-wire antenna. the C code, in Matlab or Octave get a plot by simply putting the The length of a half wave antenna is calculated using the following formula: L (ft) = 468 / f (freq in mhz). The "Super Bullet" End Fed Long Wire Antenna Matcher - 1500/3000 watt rated for Super-Punch of your signal! Links In addition to multiples, , The "Best" Random Wire Antenna Lengths 10m or 33' long. so that it is not a halfwave multiple of any frequency you want to use. SWR was good after cutting the wire to appropriate length. 3 0 obj It will be good for 15m, and 10m. >> <> << 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. In theory, my LDG Z100 Plus autotuner should be capable of matching the impedance of this 49:1 transformer with a end-fed half wave length antenna radiator across all amateur HF bands. /Name /Im0 Let's have a look at a few details on how to build a 49:1 impedance . Twist the short and long wires together starting at an end of each wire. To summarise the results WRT to reference antenna consisting of 30ft wire vertical fed with auto- The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. 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? It's an efficient way to get all the multiples One is for the top of the box so that it can be hung up. Par EF 20 and par EF 40 (I realize for 17m I would prob just add that band to a 49:1 balun) That's that my question is. << This is a 4:1 Current Balun.That means it can match a 200ohm antenna to a 50 feed line.
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