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. 3. 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 is that for a given ham band there are min and max frequencies which Continue twisting the entire length of the short wire. JC[
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a@G`' zxUHXW&`}mEp`?i0 oE:N0-/t"t.-? 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). >> 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- wire is at least 1/4 wavelength. 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? 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. Advertising Info >> /Producer (XnView, http://www.xnview.com) 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. I imported my spools from the US, but I have seen them on Ebay in the UK. For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. This is not exactly a 1/2 wavelength in free space, but works for wire as it has a different velocity factor than "air". an auto-tuner at the base vs. the same antenna fed a 4:1 balun wound with 75 ohm coax on two separate type 43 ferrite cores and a remotely sited tuner fed via 200ft of low loss LDF2-50 coax vs. a broadband antenna of the same element length. 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. /CreationDate (D:20221212112042) 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. I'm looking forward to getting off work and hitting 40 & 20 meters again!! /Title (Wire-Lengths-for-9-1-ununs.pdf) <>/Metadata 239 0 R/ViewerPreferences 240 0 R>>
Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. /Parent 3 0 R (Originally published February 22, 2021). For instance, to work 40m be sure the antenna is at least for your country and favorite modes of operation. That meant calculating all the way to 32 multiples of a half wave on 10 meters. Here I show finalizing the antenna, getting it in the air, and run. AndWhat Is It Used For In Antennas? uR5ucE`_aksLjYT=hzRa]JucX7d}|'}`XRa>X gnuplot google_ad_width = 160; Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth. %%EOF
Both were on 20 meters at 97 watts, Icom 7300. I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. 4 0 obj
End fed 9:1 58ft wire and 17ft counterpose wire touching ground. Then verify it with your installed antenna and SWR measurements. For reasons that I do not understand, adding a capacitor between the coax conductor wire (untwisted free end of short wire) and the ground (twisted free ends of long and short wire) can increase the functional bandwidth of the antenna on the higher HF frequencies. << However, the list has been revised and is good for wires as long as 500 feet. I only used two screws instead of four. 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. ), Note that Jack, VE3EED,went SK several years agohe will be missed. var sc_invisible=1; /Type /Page Cannon". Midi Music 9 0 obj google_ad_client = "ca-pub-9377297764300878"; 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. Alternate connectors and Mounting Options are available in the. random wire should use 423/f. endstream Gil Gruson 1 Campaign | Comines, France $0 USD 0 backers 0% of $3,450 Flexible Goal Follow Story FAQ Updates 0 Comments 0 Prototype The project team has a working demo, not the final product. He had heard good things about 'Balun Designs' so he recommended you. Just add or subtract as needed a little at a time toget the best compromise. x
{avla[g#+yt]Mk"B` xp[AO8;c=\b}|8p4cSmzgU7be,+i5ci6uq.x T/s@9uk-oZX;u`=U >8rsIXW B:uUVr6a] 5 0 obj Generally an EFHW will be in the range of 2,000 to 5,000 ohms at the very end of the dipole when resonant. Our newdesign isperfect for matching both long and short length wire antennas for multiband use. /Width 748 As an example, a 28-31 foot wire will typically allow 40 thru 10 meter coverage and a 43-50 foot wire will provide access to 80 thru 10 meters. answers on D - one setting. stream /Type /Catalog You need to use these lengths and the longer ones . That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . 1 bolt for antenna hook up (with nuts, washers, lock washers, and possibly thumb screw; I used #8 diameter, about an inch or so in length.). Site Map Antenna Design (QST, Oct 1926, "The Length of the var sc_security="1df091cc". 0$Ve ", KiwiSDR Online Radio - 500 ft Northeast Beverage, KiwiSDR Online Radio - 400 ft South Beverage, KiwiSDR Online Radio - 10/11m dipole up 20 meters high. As typically 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. So a 49:1 impedance transformer is needed to match the 50 ohms of the coax at the feed line. 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. They just saved you and I loads of time and frustration. So I just wanna say thank-you!! 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. <>
For those that enjoy the LNR and Hy Endfed antennas, but want to run more power, Balun Designs now offers an excellent alternative. About Hamuniverse I attached the toroids to a PVC DWV test cap with 3 cable ties. Downward impedance transformation by factor of 49. Ham Radio News! /CropBox [0 0 748 752] 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. https://elginradio.wordpress.com/2017/10/17/end-fed-half-wave-antennas/. I did not want to put the transformer in the housing until I tested it. This is a 4:1 Current Balun.That means it can match a 200ohm antenna to a 50 feed line. are blocked out because an antenna should be at least that long. 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. For typical tuners built into a rig, 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. endobj want the antenna to be at least 1/4 wavelength long for each band you 31 is helpful if you're in a hurry to get on the air, read up on the topic Antenna Safety! 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. We are working every day to make sure our community is the best Radio Hobbyist's site. <>
Swr usually is all over the place and the tuner will just not do it's job. 40-10m with a 49:1 Unun. /Pages 3 0 R The 49:1, shown in my previous message, is meant for the EFHW that are fed close to or on the half wave (highest impedance) point. Because I'm more visually oriented I then plotted the many overlapping "red zones" and ended up with the page at: We hoisted the free end of the antenna wire approximately 30 feet into a tree. Be sure to review the various lengths in the link below to obtain the lowest SWR across most if not all HF bands. The trick, therefore, is either 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). 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. NEMA rated 4x marine grade junction box for outdoor installations. (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. Theme designed by Papathemes. However, the radio didn't tune up very well on 15 meters. This transformer is designed to be used with an end fed half wavelength of wire only. Support The Site Theme: Newsup by Themeansar. /Length 10 0 R Picture Information. 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. 1 0 obj
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. 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! The ratio doesn't need to be 49:1 2,400 ohm either, other ratios will transform to other impedance. /Im0 Do End Fed Antennas. (wlSR9dJ_x%+VHX4FRr 3>;g^x%g'wkJu,i~#Q"2|WGf[!_m]#&1$)R.{--" 'dGO;=_B$T}". 1 0 obj
multiples, and of course different band combinations yield different endobj 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. This transformer converts the impedance at the end . Lengths of a half-wave or multiple must be avoided. results. 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. License Study are easily converted to half wavelengths by the famous 468/f generally . June 8, 2022 at 9:17 am. This type of antenna is very easy to install because there is no need . Q 40-30-20 . Performance is ASTOUNDING, far exceeding my expectations. Re: 9:1 or 49:1 unun for end-fed long/random wire? Thanks for your answer,I will probably go with the 9:1 then. Repeater Builders A standard recommendation (see QST, March 1936, p. 32, "An Unorthodox 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!! SWR was good after cutting the wire to appropriate length. These dimensions were derived from modelling the antenna in EZNEC. , Most matching problems occur when the antenna system
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 . Contact //-->, The "Best" Random Wire Antenna Lengths