%PDF-1.4 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. The Nelson antenna 9 to 1 unun did the trick. /Producer (XnView, http://www.xnview.com) Update guys:made the unun,the antenna was extended to about 37m length,and I added a counterpoise which is about 10m.The whole thing is much higher in the air,compared to where it was before. 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. . 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. How We Flew An End-Fed Half Wave (EFHW) Ham Radio Antenna On A - KM1NDY A good place to start is the formula 468 / f (MHz) for a 1/2 wavelength wire antenna. bands you're intested in in a vector like the example below, by typing. recommended on VE3EED's page because I use all halfwave [ /PDF /Text /ImageI ] Lengths of a half-wave or multiple must be avoided. This design is excellent for matching both long and short length wire antennas for multiband use. Start winding the Matching Auto Transformer, each pass through the center of the core equals one turn. Do what works best! Work all bands from 80 through 10 on it. CQ-Calling All Hams! 9:1 UnUn End Fed Long Wire Lengths - Pretty Simple. Here Is a 250 Watt Home-Brew That I Made In about an Hour. A few more comments about this 49:1 autotransformer EFHW design. , Reprinted with permission of Hamuniverse, this is an excellent explanation of SWR and how to best me endobj End Fed Half Wave 40-10 Wire Antenna - N6DOZ /Im0 Do I attached the toroids to a PVC DWV test cap with 3 cable ties. endobj Legal Stuff 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. I'm looking forward to getting off work and hitting 40 & 20 meters again!! You'll want to have that wire up as high as you can get.. 9:1 or 49:1 unun for end-fed long/random wire? Presented for your consideration by Jack, VE3EED. //-->, The "Best" Random Wire Antenna Lengths End Fed Antennas. Enclosure Depth: 1.250 in. often can't match it. END FED "RANDOM WIRE" HF DIPOLE 9:1 ANTENNA RELACEMENT ELEMENT ONLY $28.99 Save up to 6% when you buy more. frequencies for your country or favorite modes. Scott builds a compact random wire antenna with 9:1 Unun %PDF-1.5 % We'd really appreciate it! 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. EFHW unun Resonant Long Wire 49:1 Transformer With BNC or SO-239 Just an FYI that I thought you might be interested in. used by hams for dipole lengths. Performance is ASTOUNDING, far exceeding my expectations. Use only the white gaps for your antenna lengths, and if 9:1 or 49:1 unun for end-fed long/random wire? An excellent way to attach a long wire antenna to the Ham It Up, this 1:9 balun has an SMA output port and high-quality spring-type terminal block input for your coax. Quantity: Sold individually. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> We recently found some good information about random wire lengths that you should and should not use. Antenna Safety! 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. So is an essential piece of gear to have. 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. 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. 10m or 33' long. PDF portable multi-band End-Fed Half Wave (EFHW) antenna for 40-10m (Note: I am not satisfied with this part of the project, so I will describe it here briefly. >> Usually any wire length that is non resonant on the band or bands desired will work with the 4:1 ratio. Here is an ARRL but instead of the Jaycar core, we used an Amidon FT-240-43; anyhow, we also followed the UnUn with a 1:1 guanella choke and boxed everything, at that point, we . Advertising Info 9:1 Unun 1.5-54MHz 2kW 9132S - The DX Shop Limited x 2 in. UJM-49-1 $56.99 Save up to 6% when you buy more. /BitsPerComponent 8 In other The ratio doesn't need to be 49:1 2,400 ohm either, other ratios will transform to other impedance. 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. x@ thank you. 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. I have never tried to transmit through it, but it proved the optimal ratio for receiving with my setup. 35-43, 49-63, 70-85. 2 0 obj The First Thing New Hams Often Ask:What Is An UnUn? 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. /Parent 3 0 R 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. I actually did this first and before the connector was bolted to the box. Ham Hints Generally an EFHW will be in the range of 2,000 to 5,000 ohms at the very end of the dipole when resonant. On our next windy free day, AA1F and . Part List: 73, HF & Shortwave (Originally published February 22, 2021). multiples, and of course different band combinations yield different "Just received my new 64131 yesterday and was anxious to see how well it performed. shown in the column e. var sc_project=8077274; The most common question I get asked is what is the correct length for my End Fed Long Wire Antenna? 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. V#X~[Z?\ZcX:-Y?&Y?IqTnayZ{jTZOub}=UTWu1G>o.,RaT c=W>:sECXTkc=X 74 0 obj <>stream Again, the bands are USA, so change them doing the initial 468/f on C and D scales. These dimensions were derived from modelling the antenna in EZNEC. understand its properties. I made just a touch over 100 QSOs today with the new unit. random wire page. 40-30-20-15m bands for my 4 band Elecraft K1 qrp rig. 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. Ham Radio News! 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. /ProcSet 7 0 R >> Continue on winding the long wire through the toroid to complete loops 3 through 14 as shown in the schematic below. It is used fornon-resonant verticals like 43 foot or 33 foot Or Wire antennas like an End-Fed1/2 Wave Multiple Length Wire Antenna. Thanks for your answer,I will probably go with the 9:1 then. wire lengths less than 1/4 wavelength of the lowest desired frequency I'll get a 9:1 unun,and use a suggested random wire length to avoid half-wave and it's multiples then,that sounds like the best things I can get out of this setup. are easily converted to half wavelengths by the famous 468/f generally JC[ d8O[UKKQ{yZ{G 'Upno_*~8uo a@G`' zxUHXW&`}mEp`?i0 oE:N0-/t"t.-? Care to buy us a beer? End fed 49:1 60ft wire (using coax as the counter poise. 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. Each winding is counted when the wire enters through the center hole of the toroid. AndWhat Is It Used For In Antennas? Proudly powered by WordPress installed, it is a compromise antenna but great for portable use because for your country and favorite modes of operation. Contact SWR was good after cutting the wire to appropriate length. If the choices are. q >> I'm consistently pleased with the quality and ease of use of Balun Designs products and look forward to my next purchase in the future. 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. The fewer bands, the fewer high impedance regions to avoid. Here they are in order: %%EOF Site Map 748 0 0 752 0 0 cm 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. The vertical (y-) axis shows the VSWR and the horizontal (x-) axis shows the frequencies. Tools https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. Ultimately, this housing works fine, but it is heavy and clunky.). This will be for an eyehook in order to provide strain relief for the radiator 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. That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . I have found this calculation to work well, however it depends on many factors such as wire used, location etc. 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. Single Wire/End Fed Antenna - K7MEM $1YacO5Q}YC\>qZ } /Height 752 /Name /Im0 Power Handling (CW/SSB): 100 W/200 W Enclosure Width: 2.500 in. /Filter [ /FlateDecode ] Ham Radio End Fed Antenna with a 1:64 Matching Network This transformer converts the impedance at the end . This article explains why the use of mix 43 for HF applications is almost always a mistake. Experimenting by slightly changing the wire length (+ or-) is encouraged to provide best overall performance. This type of antenna is very easy to install because there is no need . Use a slide rule! tuner the colored bands below are the best lengths as long as your Using a 49:1 transformer shoot for the best 50 match @ appx 2450 load over your working frequency bands. 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. &nb uR5I5z G^u2`j[}+sy9 I only used two screws instead of four. 20/40/17m. End fed 9:1 58ft wire and 17ft counterpose wire touching ground. (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. PDF Construction Details 49:1 Un-Un For End-Fed Resonant HalfWave Antenna Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW - Balun Designs is that for a given ham band there are min and max frequencies which End Fed Half Wave Antenna Coupler Schematic - 7-30MHz. Wait a few minutes for glue to set. endobj 73. JACK, VE3EED 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. 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. endobj x 4 in. Anyway, an old friend mentioned 'MyAntenna.com' but they were closed for the summer. Jack, VE3EED - SK. Hi guys,not really hfu related,but I tought I might ask here as I have my account. SO-239 (UHF female) chassis mount with screws, nuts, lock washers. Attaching a counterpoise wire to the common point of the auto-transformer provides the antenna radiator something to push against rather than the coax shield. /CropBox [0 0 748 752] endobj Then verify it with your installed antenna and SWR measurements. I wrote a small C program that does just what Jack did, butI used the band edges. End Fed Half Wave Antenna Coupler (EFHW) - M0UKD In addition to multiples, . 49:1 EFHW Antenna 40-10M 100W - M1ECC-Antennas 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. 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 trick, therefore, is either uR5ucE`_aksLjYT=hzRa]JucX7d}|'}`XRa>X For those that enjoy the LNR and Hy Endfed antennas, but want to run more power, Balun Designs now offers an excellent alternative. PDF shortened multi-band End-Fed Half Wave (EFHW) antenna for 80-10m This undesired reflection of RF power back toward the transceiver is identified as a high voltage standing wave ratio (VSWR or SWR). For best results, use the Wire Length Feet 1.8 MHz 3.7 MHz 5.3 MHz 7.1 MHz 10.1 MHz 14.2 MHz 18.1 MHz 21.2 MHz 24.9 MHz 28.5 MHz 50.1 MHz endobj Prescott Hamfest 2023 Saturday - May 13, 2023 - 0800 to 1200 MST Granville Elementary School 5250 Stover Drive, Prescott Valley, AZ 86314 The 2023 Prescott Hamfest is co-sponsored by the Yavapai Amateur Radio Club (YARC) and the Amateur Radio Council of Arizona (ARCA). Use with other lengths can potentially damage the transformer depending on power level in use. 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!!

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