We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. 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. thank you. >> K1S Valentines Are (Almost) Out The Door! The WSPR map is so dense it looks like the US and Europe are just big blobs of color. For typical tuners built into a rig, Designed for use with single wire unbalanced antennas, this new addition is small, compact and perfect for quick portable/emergency installations. The bandwidth where SWR was below 2:1 was about one MHz. 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] For example, In other this For instance, to work 40m be sure the antenna is at least 20/40/17m. 32.00. "Can you please recommend schematics that are designed to tune setups like these? endobj Balun Designs. The fewer bands, the fewer high impedance regions to avoid. 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 . Turns 1 & 2 are primary windings (the short wire). You are using an out of date browser. X:nzf4p:t;r }~_HOZcX:^$* J^XZuu|"nX/Wkw0hA>y1(z2+v_Xzu[/:^$*m*>hk_:+c{ EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 | Mobile Phones & Communication, Radio Communication Equipment, Antennas | eBay! The length of a half wave antenna is calculated using the following formula: L (ft) = 468 / f (freq in mhz). (A t0 B) Fold over 6 to 8 inches and twist it together. In total 29 contacts were made from British Columbia to Texas to Florida in 40 minutes on 20M. x {avla[g#+yt]Mk"B` xp[AO8;c=\b}|8p4cSmzgU7be,+i5ci6uq.x T/s@9uk-oZX;u`=U >8rsIXW B:uUVr6a] This transformer is designed to be used with an end fed half wavelength of wire only. Drill another hole in the same side as the antenna radiator wire mount hole. multiples, and of course different band combinations yield different 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. <> 80m up, W3EDP's 84' antenna, 17' counterpoise is probably the way to go. Thanks for your answer,I will probably go with the 9:1 then. and experiment. << 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. One end goes straight into the Save program output in file named 'f', and use /BitsPerComponent 8 >> Solder a the 100pF capacitor between the center conductor wire and ground wires. Here Is a 250 Watt Home-Brew That I Made In about an Hour. The counterpoise wire, This transformer is designed to be used with an end fed, Approx. 74 0 obj <>stream 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. Well then you need to choose a wire length that is at least 1/4 on 40 meters, and doesn't fall on any of the 1/2 multiples for ALL the bands between 40 to 10 meters While you could certainly calculate the lengths to avoid using the standard formulas, and then make a chart, the section below may be what you are looking for. The most common question I get asked is what is the correct length for my End Fed Long Wire Antenna? <> Start winding the Matching Auto Transformer, each pass through the center of the core equals one turn. If the choices are. Vacation Closure - See Homepage for Next Availability. I used the RigExpert Zoom AA-55 to test VSWR of the 49:1 unun impedance transformer. /Width 748 it is easy to pack and easy to install. >> Winding 1:64 Matching Auto Transformer on the FT240-43 core. google_ad_slot = "1982258389"; 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). 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. 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. 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. We are working every day to make sure our community is the best Radio Hobbyist's site. 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. This may not be relevant to HF stuff, but the antenna I use for NDB reception has a 400:1 transformer (20:1) turns ratio. , This is a partial reprint (with permission) of an excellent series of articles published by KV5R Hope it's clear now, if not. A VSWR sweep of the unun after adding a 100pF capacitor shows an SWR <5:1 from 160M to 10M. Lowest Band of Operation: 160 meters Highest Band of Operation: 10 meters Additional Information LDG Electronics RU-9:1 Unun End Fed Half Wave Antenna Coupler Schematic - 7-30MHz. endobj VSWR analysis of the antenna in the field showed that VSWRs between 3-5.5 from 40M to 10M. are easily converted to half wavelengths by the famous 468/f generally Here I show finalizing the antenna, getting it in the air, and run. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 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. The second smallest number I measured was 2.7pF, derived from the self resonance at 2.72 MHz with the magnetizing inductance (measured at 25.8 H) with the secondary open and the output wire folded to a small 1/2 length. Swr usually is all over the place and the tuner will just not do it's job. Ultimately, this housing works fine, but it is heavy and clunky.). /Title (Wire-Lengths-for-9-1-ununs.pdf) A good place to start is the formula 468 / f (MHz) for a 1/2 wavelength wire antenna. Wait a few minutes for glue to set. 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. Theme: Newsup by Themeansar. 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. Cannon". 1 0 obj Part List: recommended on VE3EED's page because I use all halfwave Superglue 2 toroids together. I connected it to a 33 wire running from my balcony, through the trees, and ran WSPR overnight to check things out. 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. ones 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. Liquidtight NM 90-Degree Connector(Home Depot). Antenna Design The novel thing was that I only built it the day before and it uses a Coghlan camping washing line spool with the string taken off and about 21m of wire wound onto it. /Type /Catalog Proudly powered by WordPress uR5ucE`_aksLjYT=hzRa]JucX7d}|'}`XRa>X 1 0 obj Modify bands and Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands. used by hams for dipole lengths. /ModDate (D:20221212112042) Jack, VE3EED - SK. 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. Advertising Info 3 to31 MHz - up to 1kW intermittent (50% duty cycle). Superior Essex Heavy build polyamideimide. At multiples of half wavelengths of the <>/Metadata 239 0 R/ViewerPreferences 240 0 R>> A few more comments about this 49:1 autotransformer EFHW design. 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. The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. First, it is important to understand the difference between the end fed half wave and a random wire (or "long wire") antenna: the random wire is just a piece of wire that is matched to 50 Ohm impedance using an antenna coupler, sometimes adding a 9:1 unun. This is not exactly a 1/2 wavelength in free space, but works for wire as it has a different velocity factor than "air". << % 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. Click to enlarge. One is for the top of the box so that it can be hung up. The unun was floating at about 15 feet above ground. IMG_2.jpg Step 2: Take the 6 feet of 18 gauge enameled copper wire, measure 11" from one end and fold it back. 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. /Type /Pages While I have not done so yet, I plan on gluing the test cap to the back of the junction box. 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. q The table below represents half wave lengths and multiples that you DO NOT WANT TO USE! Repeater Basics 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. 35-43, 49-63, 70-85. /Kids [ 4 0 R ] End fed 49:1 60ft wire (using coax as the counter poise. 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 The most important length is one that is non-resonant on any band. He had heard good things about 'Balun Designs' so he recommended you. Enclosure Depth: 1.250 in. /ProcSet 7 0 R >> HF & Shortwave The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. Longer wire is always more I only used two screws instead of four. InJack's own words. The length should be calculated based on the lowest frequency to be worked. the C code, in Matlab or Octave get a plot by simply putting the 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. 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. This type of antenna is very easy to install because there is no need . The idea << The Short Answer Would Be That an UnUn Is a "UN balanced to UN balanced" matching transformer. This calculates to 4.2 m or 14 ft for an 80m end-fed. . Here Is a 250 Watt Home-Brew That I Made In about an Hour. JavaScript is disabled. Do what works best! you're using different ham bands than in these examples, modify and rerun The Short Answer Would Be That an UnUn Is a UN balanced to UN balancedmatching transformer. 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. PVC Junction Box(Home Depot), 1 x 1/2 in. Antenna Safety! It is optimized for 3.5/7/10/14 MHz but will work reasonably well on all amateur bands from 80 meters thru 10 meters with a 135 foot length of wire and a short connection to ground. 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. a more capable tuner - see AA5TB's SWR will vary based on topography, wire orientation and use of ground or counterpoise. 2 0 obj Ham Radio News! Step 1: Drill holes for and install the SO-239 or BNC connector, the stainless steel machine screw antenna connector and the ss machine screw ground connector. Just add or subtract as needed a little at a time toget the best compromise. Here's a list of recommended lengths of wire to use with a 9:1 unun. Humor 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.). endstream On our next windy free day, AA1F and . I made just a touch over 100 QSOs today with the new unit. rig, often with no feedline, and the other end in the air attached to 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. are blocked out because an antenna should be at least that long. endobj (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. "Just received my new 64131 yesterday and was anxious to see how well it performed. Both were on 20 meters at 97 watts, Icom 7300. Note: My (A to B) length was 6 inches. endobj Let's have a look at a few details on how to build a 49:1 impedance . endobj The "Super Bullet" End Fed Long Wire Antenna Matcher - 1500/3000 watt rated for Super-Punch of your signal! wire is at least 1/4 wavelength. shown in the column e. var sc_project=8077274; stream answers on D - one setting. %PDF-1.5 When you're antenna (or radial) length's an odd multiple of the operating freq, you may not need a balun or even a transmatch. Here is an ARRL . So a 49:1 impedance transformer is needed to match the 50 ohms of the coax at the feed line. About Hamuniverse EFHW unun Resonant Long Wire 49:1 Transformer With 67' Antenna Wire. This article details the construction of the transformer. 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. This antenna, which works on 10, 15, 20, and 40 meters, has a very high impedance of around 2,500 Ohms. 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. /Type /Page Lengths to avoid are not always the same as Stacked coreswithwinding configured as 49:1auto transformer. and leave the unun on the ground. The counterpoise wire does not have to be similar in length to the main radiator wire and just a short wire is all that is needed, about 0.05 . so that it is not a halfwave multiple of any frequency you want to use. Ham Hints So for example 80m could range in length from 120 to 133 feet. endobj program or two to do all the dirty work. /XObject << /Im0 9 0 R >> Powered by BigCommerce. <> Our newdesign isperfect for matching both long and short length wire antennas for multiband use. STORE The other is to provide strain relief for the antenna wire). For example a 32 foot length is actually a half wave on 20m with an impedance of about 3500 ohms and requires a 50:1 balun. endobj You need to use these lengths and the longer ones . Code Practice %PDF-1.7 The beauty of the halfwave antenna is it's a complete antenna in the sense it needs no counterpoise. So I just wanna say thank-you!! tuner the colored bands below are the best lengths as long as your This homebrew 49:1 impedance transformer is the heart of any EFHW antenna you will build, most of the time. This was 9m vertically metres up a fishing pole and then about 5.8m out. Well, I didn't think it would make any difference at that many multiples. /ColorSpace 11 0 R 3. 10m or 33' long. I connected the free twisted end of the short and long wires (the ground) the chassis wire (ground) of my homemade testing jig with alligator clip. /Pages 3 0 R Support The Site 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. random wire should use 423/f. The graph below shows lengths to avoid for different collections of bands. UJM-49-1 $56.99 Save up to 6% when you buy more. 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 Model 9135 along with one of the wire lengths shown in the Installation Notes. For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. Downward impedance transformation by factor of 49. hb```YloD@(aKI V!}g@~}%Q/[[~_=Wy-:O)x[~hs/~SGeG _QE C6q %r presents an extremely high impedance to the tu bands you're intested in in a vector like the example below, by typing. Free Postage. Start winding the toroid with the twisted wires at loop #1 (see schematic below). Make sure the beginning few inches of twisted wire is not involved in the winding (i.e., just hanging down from the toroid). Usually any wire length that is non resonant, like those shown above, will work with the 4:1 ratio. understand its properties. In stock . var sc_invisible=1; 9:1 UnUn End Fed Long Wire Lengths - Pretty Simple. 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. Recommended wire lengths for Unun models 9130, 9132 & 9135 Table shows typical SWR relative to installed wire length. I sent him the link to the 49:1 unit to get his feedback. /CreationDate (D:20221212112042) He knew that in order for the tuner to "see" a fairly low swr to work within it's range,that the antenna had to be NOT A HALF WAVE ON ANY FREQUENCY that we wanted to us, because a half wave will give us a very high impedance and the resultingswr into a 50 ohm transmitter! A 9:1 unun is a transformer that reduces the impedance at the input by a factor of 9. endstream endobj startxref You'll want to have that wire up as high as you can get.. >> However, the radio didn't tune up very well on 15 meters. He was so impressed that he purchased a 9:1 unit from you, his will be delivered Saturday. Tune Around! My homemade 49:1 EFWH with a 60 wire (cut for 40M) would do just fine! 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. To summarise the results WRT to reference antenna consisting of 30ft wire vertical fed with auto- Just add or subtract as needed a little at a time to get the best compromise. I won't bore you with all that so the first portion of this still only shows up to the 4th multiple. //-->, The "Best" Random Wire Antenna Lengths 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. The major point of this message is to tell you that approximately 20 minutes after I connected the balun unit to the antenna, I made contact with a gentleman in Italy-my first European contact!! 3 0 obj 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. The 49:1 End Fed Half Wave Antenna is very popular choice for home & field use, Ideal for limited space and stealth applications. Some of these numbers are too close to squeeze in between them. Random wire lengths you should and should not use! I have included a screenshot showing the stations that reported spotting my 200 mw beacon over the last 16 hours. Mike ab3ap, Editors note: Many thanks to Jack, VE3EDD (SK)and Mike, AB3APfor sharing their math and computerskills with us. /Length 10 0 R endobj Any SWR measurement taken with the transformer at the feedpoint should not exceed 1.5:1withNOtuner in use. Because I had some spare Cu-Wire I wound another 1:49 Unun on a smaller FT-140-43 toroid and tried different capacitors between feedline and ground (to compensate for the 10m band). stream You also A small ring terminal for 14ga wire that fits these screws would be helpful too. Windings are inserted into Teflon tubes increasingtotal breakdown to 10,000 volts. He used 300 ohm twin-lead and a 4:1 UNUN, with a 1:1 current choke between the UNUN and the coax to the tuner and transceiver: The full-size "flimsy" (ref. /Creator (XnView) The transformer usually used with an end fed wire is a 9:1 transformer. A standard recommendation (see QST, March 1936, p. 32, "An Unorthodox https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. << This is considered a random wire end fed antenna, not to be confused with a half wave end fed antenna which uses a 49:1 or 64:1 unun and a wire that is a half wave length. I have not done this yet. W3EDP's results in the above referenced End Fed Antennas. plan to use. SEARCH Because I'm more visually oriented I then plotted the many overlapping "red zones" and ended up with the page at: The vertical (y-) axis shows the VSWR and the horizontal (x-) axis shows the frequencies. 49:1 UNUN IMPEDANCE XFORMER FOR END FED HALF WAVE ANTENNA. The length should be calculated based on the lowest frequency to be worked. =======================, More on Random Wire Lengths from Mike, AB3AP (06-29-2012), I was surfing around Hamuniverse.com and found thIs page on random wire antennas: I wrote a small C program that does just what Jack did, butI used the band edges. Midi Music In another life, I could have been a telephone engineer. Using a 49:1 transformer shoot for the best 50 match @ appx 2450 load over your working frequency bands. Wire lengths for the 4:1 ratio in models 4932 and 4935. This transformer is designed to be used with an end fed half wavelength of wire only. 25 0 obj <> endobj So, having nothing better to do one day, I re-did the calculations going out to 500 feet. However, the list has been revised and is good for wires as long as 500 feet. Bullet 50:450 (9:1) HF Unun, 1.8-61 MHz, 1500 Watts, End Fed Antennas. endobj 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. There are numerous configurations available online that will accomplish this on multiple bands (Google search "end fed half wave antennas"). 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. After winding #2 is made and extends down the backside of the toroid, untwist the wires. stream endobj That's it in a nutshell..or is it? 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. If you want a single band portable antenna you can mount pretty much however, look up this design. Again, the bands are USA, so change them 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. 75/80 METER RESONATOR KIT FOR THE UJM-EFHW-40-10 200W 40-10m ANTENNA End fed 9:1 58ft wire and 17ft counterpose wire touching ground. I have never tried to transmit through it, but it proved the optimal ratio for receiving with my setup. 10C) for the 10-80 m bands, or even 6-160 m: 17 ft (5.2 m) of twin-lead and 68 ft (20.7 m) of antenna wire (i.e., standard dimensions). 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. (wlSR9dJ_x%+VHX4FRr 3>;g^x%g'wkJu,i~#Q"2|WGf[!_m]#&1$)R.{--" 'dGO;=_B$T}". This article explains why the use of mix 43 for HF applications is almost always a mistake. high the other 1.5m (4.5feet). 73. JACK, VE3EED V#X~[Z?\ZcX:-Y?&Y?IqTnayZ{jTZOub}=UTWu1G>o.,RaT c=W>:sECXTkc=X %%EOF /CropBox [0 0 748 752] 1 0 obj 9:1 Unun EF Random Long wire matching Transformer with BNC or SO-239. << There are so many new frequencies to stay away from, that it gets pretty tricky for the longer wires. Just an FYI that I thought you might be interested in. There probably should be some holes for ventilation. google_ad_height = 600; here are values for CW portions of the USA 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. Tools ), Note that Jack, VE3EED,went SK several years agohe will be missed. . (Also check out AB3AP'Swebsite and say thanks for sharing his skills. RFI Tips and Tricks Cut a 4 foot length of AWG #18 enameled wire. Continue twisting the entire length of the short wire. 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. Antenna") is an 84' long end fed and a 17' long counterpoise (6.5' for 20m). Wire lengths for the 4:1 ratio in models 4130, 4132, 4134, 4932 and 4935. 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. If you plan on stringing up a dipole you use 2 equal lengths of wire with the Balun in the middle. SSTV $1YacO5Q}YC\>qZ } We'd really appreciate it! In fact, the 9:1 unun that I built is actually an autotransformer. To DB's point of a single band antenna, this 49:1 transformer is a good choice for a single band matcher. Yes, with the recent surge in popularity of the end-fed half-wave antenna, the 49:1 balun has also become the defacto ratio for use with them. 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 . One single wire, no solder connections,very simple.all the way from the tuner to the end support. 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. You can take one of these 49:1 transformers and use the 468/freq (Mhz) formula to calculate the length you need in feet. . The ratio doesn't need to be 49:1 2,400 ohm either, other ratios will transform to other impedance. That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . Continue on winding the long wire through the toroid to complete loops 3 through 14 as shown in the schematic below. Designed for those who want the maximum isolation and choking across the full HF spectrum.
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