These dimensions were derived from modelling the antenna in EZNEC.
EFHW Antenna and 49:1 UnUn | WorldwideDX Radio Forum >> << He was so impressed that he purchased a 9:1 unit from you, his will be delivered Saturday. A 9:1 matches 50 ohms to 450 ohms and that turns out to be an ok compromise for feeding 50-100ft of wire for general purpose SW receive. endstream You will note that when comparing my results with VE3EED that some of the results are a bit different. [ /PDF /Text /ImageI ] Shortwave Listening Tweak the antenna length if necessary and then maybe adjust the turns ratio again. << document.getElementById("copyright_year").innerHTML = new Date().getFullYear(); 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. InJack's own words. So for example 80m could range in length from 120 to 133 feet. I have never tried to transmit through it, but it proved the optimal ratio for receiving with my setup. 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. We are working every day to make sure our community is the best Radio Hobbyist's site. The popular End-Fed Half-Wave (EFHW) Antenna is an easily portable, high-impedance (2,000-4,000 ohm) wire antenna that resonates on its fundamental frequency and all harmonics above. So after much frustration..down it comes and you go on to a totally different type of antenna.all that time just wasted inyour opinion..until now! .
Experimenting with 1:64 and 1:49 end-fed antenna Ununs on - reddit 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. 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. That meant calculating all the way to 32 multiples of a half wave on 10 meters. Free Postage. Liquidtight NM 90-Degree Connector(Home Depot). results. I connected it to a 33 wire running from my balcony, through the trees, and ran WSPR overnight to check things out. End fed 49:1 60ft wire (using coax as the counter poise. The table below represents half wave lengths and multiples that you DO NOT WANT TO USE! See the picture below.
So those are the numbers above thatwe have to stay as far away from as possible when building a long-wire antenna. Alternate connectors and Mounting Options are available in the.
multiples, and of course different band combinations yield different 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. The following wire connections do not need to be made in the order I described.
Unun 9:1 - VK6YSF - Home Page /BitsPerComponent 8 For typical tuners built into a rig, Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. W3EDP's results in the above referenced endstream
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Enclosure Depth: 1.250 in. The bandwidth where SWR was below 2:1 was about one MHz. Superglue 2 toroids together.
PVC Junction Box(Home Depot), 1 x 1/2 in. If you want a single band portable antenna you can mount pretty much however, look up this design. /Height 752 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.
How We Flew An End-Fed Half Wave (EFHW) Ham Radio Antenna On A - KM1NDY This transformer is designed to be used with an end fed half wavelength of wire only. . endobj /Length 6 0 R 9:1 Unun EF Random Long wire matching Transformer with BNC or SO-239. x
{avla[g#+yt]Mk"B` xp[AO8;c=\b}|8p4cSmzgU7be,+i5ci6uq.x T/s@9uk-oZX;u`=U >8rsIXW B:uUVr6a] 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. 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. often can't match it. Hopefully these random wire length calculations will help us all make this "easy" antenna work better! 9:1 Unun 1.5-54MHz 2kW 9132S. SO-239 (UHF female) chassis mount with screws, nuts, lock washers.
End Fed Half Wave Antennas - Elgin Amateur Radio Society 2 0 obj Two pieces of 14 gauge enameled wire (e.g., Thermalese), one short piece (about 1 foot in length) and one long piece (about 7 feet in length).
Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW - Balun Designs End Fed Half Wave Antenna Coupler (EFHW) - M0UKD 1:1, 9:1, 49:1 Matching Units - What's the difference? - YouTube You are using an out of date browser. Lengths to avoid are not always the same as 1 0 obj
End Fed Half Wave Wire Antennas | N6CC http://udel.edu/~mm/ham/randomWire/. 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. 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. want the antenna to be at least 1/4 wavelength long for each band you That is the 10th multiple of a half wave on 15 meters. 20/40/17m. Product Reviews /&KWA7{L=D]g0Z!F9;V{zL[h-D,u(.9rg(RHI{f t*C/?? 80m up, W3EDP's 84' antenna, 17' counterpoise is probably the way to go. Superior Essex Heavy build polyamideimide. wire lengths less than 1/4 wavelength of the lowest desired frequency The idea Just an FYI that I thought you might be interested in. While these lengths have been shown to work well on many bands, which Built with the same craftsmanship as all our other For those that enjoy endfed antennas but want to run more power, Balun Designs now offers an excellent alternative.
49:1 impedance transformer UNUN - Wire Antennas Make sure the beginning few inches of twisted wire is not involved in the winding (i.e., just hanging down from the toroid). This will be for an eyehook in order to provide strain relief for the radiator wire. 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. 1 0 obj
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This calculates to 4.2 m or 14 ft for an 80m end-fed. 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. >> Re: 9:1 or 49:1 unun for end-fed long/random wire? 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. Beginning from the 3rd band from the left, the vertical blue lines are: 160M, 80M, 60M, 40M, 30M, 20M, 17M, 15M, 12M, (11M), and 10M bands. 59 0 obj
<>/Filter/FlateDecode/ID[<81C501BAF3AD19DF6B2122F37F15AF84>]/Index[25 50]/Info 24 0 R/Length 149/Prev 898971/Root 26 0 R/Size 75/Type/XRef/W[1 3 1]>>stream
and leave the unun on the ground. 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. Here I show finalizing the antenna, getting it in the air, and run. However, the radio didn't tune up very well on 15 meters. On our next windy free day, AA1F and . %%EOF
PDF portable multi-band End-Fed Half Wave (EFHW) antenna for 40-10m Support The Site 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? I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. Work all bands from 80 through 10 on it. I have included a screenshot showing the stations that reported spotting my 200 mw beacon over the last 16 hours. Turns 1 through 14 are secondary windings (the long wire). 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. SEARCH So for 80 meters (say 3.525 MHz) this gives you about 133' of wire. 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 . 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. Some of these numbers are too close to squeeze in between them. Power Handling (CW/SSB): 100 W/200 W Enclosure Width: 2.500 in. /CropBox [0 0 748 752] <>
You have to give up a band or two, like 60m and 6m, as Modify bands and RFI Tips and Tricks End fed 9:1 58ft wire and 17ft counterpose wire touching ground. Vhf and Up Theme: Newsup by Themeansar. plan to use. wire is at least 1/4 wavelength. it is easy to pack and easy to install. Figure 2 Schematic of the 9:1 voltage unun . , This is a partial reprint (with permission) of an excellent series of articles published by KV5R 9:1 or 49:1 unun for end-fed long/random wire? A 9:1 unun is a transformer that reduces the impedance at the input by a factor of 9. If you plan on stringing up a dipole you use 2 equal lengths of wire with the Balun in the middle. &nb 2 0 obj
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That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at .
You have to stay away from a half wavelength on any frequency. That's it in a nutshell..or is it? 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.
PDF 33ft Verticals and 4:1 Ununs - G8JNJ Jack, VE3EED - SK. 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.
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