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. Its really an impedance transformer (9:1) to feed a high impedance, end fed (unbalanced) random wire which is likely to be a few hundred ohms, and transform it into something closer to a 50 (unbalanced) coaxial input, hence UnUn. You have to stay away from a half wavelength on any frequency. The random wire antenna is probably one of the least expensive, easiest and cheapest HF antennas to use if you have a tuner and you want to get the "most" out of a length of "random" wire without having to pull out that calculator, doing the math, getting the center insulator built orbought, running the feedline, and all the rest that goes with putting up a more elaborate antenna. (Center fed is so appealing because you avoid this.). IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. q Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. Midi Music This article details the construction of the transformer. Turns 1 through 14 are secondary windings (the long wire). /Im0 Do 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- Support The Site I used 2000 and 1000 ohm resistors in series connected to the proper unun wires with alligator clips for a total of 3000 ohms. Bullet 50:450 (9:1) HF Unun, 1.8-61 MHz, 1500 Watts, End Fed Antennas "I received my third balun from Balun Designs this afternoon. % I included the tools I used to analyze the transformer as well; this is only necessary if you are interested in analyzing your project. Use with other lengths can potentially damage the transformer depending on power level in use. For instance, to work 40m be sure the antenna is at least 10m or 33' long. This was 9m vertically metres up a fishing pole and then about 5.8m out. >> You are using an out of date browser. /ProcSet 7 0 R >> j#f5(fk0?P[polEo5b2-/oVZu1Qo-I6C/M@TbddPc#cdZZ|7+|o{}!F#?Go7ju|?wwgow/c2/W-m~~hn[S29OU}}r7lc]wsw[shS[#qbrrK[7*0,Xv{k+o {=*vo S__O~*=y/zk75O?yjCnXS{`~Ii'c_GxN. You can take one of these 49:1 transformers and use the 468/freq (Mhz) formula to calculate the length you need in feet. This is a followup video to #344 where I assembled the 49:1 UNUN kit from HF-Kits / ARRL. V#X~[Z?\ZcX:-Y?&Y?IqTnayZ{jTZOub}=UTWu1G>o.,RaT c=W>:sECXTkc=X ?7{*. So, if you connect a length of wire that presents an impedance of about 450 to the input, you'll get an impedance of about 50 on the output. I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. google_ad_slot = "1982258389"; We recently found some good information about random wire lengths that you should and should not use. So for example 80m could range in length from 120 to 133 feet. 9:1 Unun 1.5-54MHz 2kW 9132S - The DX Shop Limited A standard recommendation (see QST, March 1936, p. 32, "An Unorthodox /Contents 5 0 R If the choices are. The 49:1 End Fed Half Wave Antenna is very popular choice for home & field use, Ideal for limited space and stealth applications. EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 REVISED: 16 19 22 26 32 33 38 44 46 48 52 64 65 66 76 78 80 88 92 95 96 99 104 110 112 114 123 128 130 132 133 138 144 152 154 156 160 165 171 176 182 184 190 192 195 198 208 209 220 224 228 230 231 234 240 242 246 247 256 260 264 266 272 276 285 286 288 297 304 308 312 320 322 323 325 330 336 338 342 352 361 363 364 366 368 369 374 380 384 390 396 399 400 414 416 418 429 432 437 440 442 448 455 456 460 462 464 468 475 480 484 494 495 496. 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. You need to use these lengths and the longer ones . 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. 2 0 obj InJack's own words. Scott builds a compact random wire antenna with 9:1 Unun A level of 500-600 watts is the maximum with a further reduction onany band measuringabove 3:1. An UNUN is needed to match the high impedance of an end fed antenna (2k-4k ohms range). Power Handling (CW/SSB): 100 W/200 W Enclosure Width: 2.500 in. Odds are that most lengths are fine though, so the easiest solution is to pick a length based on something else (like, the room you have available) and if you get unlucky, roll the dice again. 9:1 or 49:1 unun for end-fed long/random wire? It may not display this or other websites correctly. A couple hours later when I sat down to do some more DXing, I made contact with a gentleman in Slovenia-my second European contact. << (Also check out AB3AP'Swebsite and say thanks for sharing his skills. /Length 10 0 R Y &lD30. (A t0 B) Fold over 6 to 8 inches and twist it together. It's an efficient way to get all the multiples 1936 article, however, fall in line with 468/f and so is used here. In stock . stream In total 29 contacts were made from British Columbia to Texas to Florida in 40 minutes on 20M. /Parent 3 0 R STORE