To mitigate the voltage issue mentioned above, I used a couple layers of Kapton tape over the secondary winding. In an ideal setting, the center of the antenna will have the lowest voltage, consequently impedance, which is why it is possible to feed it by 50 or 75 coaxial cable. Tackling both of these issues at once led to a much smaller, lighter, and less costly transformer with better loss characteristics than previous designs. 100W on a Wire Antenna How far would it reach? The commonly used primary compensation capacitor does not work very well for this winding method which keeps the leakage inductance as low as it does. Klubunknl folyamatos a tagfelvtel. The vector sum total of all currents flowing on various physical antenna wires plus other currents like CMC on the transmission line or parasitic induced currents on masts or nearby objects must always be equal to zero. A radio station is as good or as bad as the antenna it has. The SWR results are as follows: Considering the compromised installation (ends about 2.5-3m above ground, inverted V with peak at 8m) I am pretty happy with this so far. Another design by KB0ZZ is a little longer, but resonates on both 40m and 80m. I particularly want to know how counterpoise affects the common mode currents on the coax. The blue trace above shows the results of adding a 6-turn 2 coil about 6.5 ft. from the box. Some hams swear by them, yet some completely demean it. It is common to use compensation coils of a few turns of the antenna wire to improve the alignment of the bands. The coil came out at 89mm in length rather than the theoretical 83mm not surprisingly, but the inductance was bang on at just over 109H. A ktelez mezket * karakterrel jelltk. Firstly, bandwidth on 80m is restricted to about 80 kHz at . Consider the RC time for a source with 2500 impedance into a 1pF capacitor. This article will describe a 40/30/20m band end-fed half wave antenna, focusing on its matching unit. This provides proper insulation from the relatively high voltages on the seconder winding. In comparison to the EFHW antenna, a simple dipole offers a far better prospect. (30 votes, Rating: 5.00) - Please vote the article with your valuable star rating. stream More designs can be found by Googling "80m loaded dipole.". Once that's done, the instructions say "adjust the coil as necessary" to bring the other bands into resonance. The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. This condition is rarely met in typical amateur radio EFHW antenna deployments leading to compromised overall antenna system performance. It is quite possible that designing more than three or four bands into a tuner will lead to a failure. xZ Wxi@@=\A,Y1I0E~?)JdWfe.z/|iqLI?>BPo>Pf*w~]WZu.VZZZM5zjO=?`yC^l_-H{q|m|U]21xgS6~ltFGZH}(6FE4n0D9Klx`T/;! So, I embarked on testing it for myself. Could it be something to do with the new vertical aerial I had recently installed? Another completed tuner, which is more compact then the pervious one shown, also it is lighter, more suitable for portable operations. Or transmitting about 50% of the time, the peak power you would want to run with would be about 300W. Performance of 49:1 Ferrite CoreTransformers, 24 Hour Animated PSK Reporter ReceptionReports. In the open-box image above you can see the thermal probe I used to measure the ferrite core temperature for a thermal characterizations. Can I get away with no capacitor in my design? VK1OD.net (offline). Let's find out! I went with a 49:1 unun to match the unbalanced antenna to the unbalanced feed line. The 6-turn loading coil lowers the resonant frequency into the CW portion of the 80 meter and higher bands. The cooling curve I measured is shown below. In this case =1058 seconds, about 18 minutes, is the characteristic thermal equilibration time in still air. 0 7t8An. }pKumm" t7Vb55nx S;/E}*+RS'|(q&wA;n";&.'KDff9H0^SF7 O0~{h9*QX\Mwk> u)Y h&kvDc%=(]F_$?6!:\EsM4"+>R%;93|"Jn\j+1 z}?>xBaR3 c +U+WLX`\Ld.Q2.VDHh']o.)k;a6*~s" This illustration provides a graphical view of approximate comparative difference in expected Common-Mode-Current (CMC) that could flow on the transmission line to undermine the overall performance of the antenna system. How badly can high Local Ambient QRM affect HF Radio? A transformer was wound on a FT50-43 toroid with 3 bifilar turns followed by another 31 turns of #26 enameled magnetic wire. The toroid with its many taps may be soldered directly on a multi-position switch. Saturation of a warm core happens near 0.2 T (2000 g) and if you dont want to deal with significantly reduced permeability, then better to limit to 0.1T. I think the idea is to begin by tuning 40m operation, adjusting the wire length as needed. Steps to improve the heat transfer over the present design could make this small transformer work at even higher power levels. The overall lenght is only 15m. Understanding Antennas The Good, the Bad, and the Ugly. Two layers of 1mil Kapton tape are placed over the winding. The blue trace above shows the results of adding a 6-turn 2 coil about 6.5 ft. from the box. . Above 7MHz, there is very little temperature dependence at all. The results are presented below. 2) Winding capacitance and leakage inductance, especially present as you increase the number of turns, limit the high frequency performance. . The tests here were using a dummy load on the transformer, and that did allow confirmation of the design and expected loss at 3.6MHz. From the condition, it looked like it had been installed outdoors for a few years, so I got it at a good price. I chose to use FT8 transmissions for this test since they generate 100% duty cycle during the transmission period with an average duty cycle of 12.6 sec / 30 sec = 42% overall when including the listening periods. Finally the tank circuits specification is complete, which is sown below. Graphed with a log scale, it makes a nice straight line. With tension on the antenna wire, you can just roll the coil up/down the wire to try different positions as you are optimizing for a particular band. Throw one end of the antenna wire, extended with a rope, as high as you can on a three, and walk away with the other end and attach it to the tuner. The total lenght is about 15mtr only and using 2 coils and a little stub (s) on the 80m coil or/and the 40m coil. It is worth experimenting with its length also. The impedance matching circuit is essentially a simple parallel resonant LC circuit. I placed the box in a cool oven and let it get up to about 200 F, soak for a while, and then I took it out, hung it in still air and measured the temperature as time passed and the box cooled. From experience, I found that with this tuner my SWR was better by simply disconnecting the counterpoise at lower bands. It is fun to build them and measure the lower and upper frequency limits and to see how close the calculation was. Transmitting on 15 meters was impossible because of RF into the radio. Do I count the six loops around the pvc in the measurement? The SWR for the 20 meter EFHW antenna was < 1.2:1, The SWR for the 40 meter EFHW was ~1.4:1 for 40 meters and 1.2:1 for 20 meters (full wavelength), For my 20, 30 and 40 meter EFHW antennas I will not use a capacitor in the primary. In case you need to perform calculations, use the formula: Where the frequency f is in MHz and the inductance L is in H. I have been searching the internet for a very long time (AA5TB, VK3YE, SOTA Reflector, among MANY others), and your posting finally made clear for me the many questions I have had. For calculating the length of a half wave in metres, I use 141 (MHz) for wire elements. A week or two later I started to notice an occasional knocking sound inside the house. The following is the most up-to-date information related to EFHW Compensation Coil Experiment. A half-wave at the lowest band of interest will also work well on all harmonically-related bands which has become particularly attractive to those wanting a quick portable wire antenna. To explore parameter space a little, I modeled a couple of lengths for the counterpoise and see how the wire is resonant across the band when fed with various impedances at the driven point. On top of the first wire, wrap a second one around the toroid three times (I used a red wire for this). Note that there is some uncertainty in the measurements, but we can be confident that the loss is no where near the figure estimated for the FT82-43 design. The above illustration displays a typical set of Azimuth and Elevation sections of the radiation patterns that one might expect from a horizontally configured EFHW Wire Antenna deployed at an average height of 40 ft. above ground level (AGL). 101: The Independent Medical Evaluation - "IME" By: Cynthia M. Hennessey Attorney. Impressive article and so well done that I may give it a try. This could be achieved by: Using thicker wire; increasing the diameter/length ratio; using a low loss former. Nevertheless, the EFHW antenna had in the past, been rather sparingly used by amateur radio operators due to various reasons. The in-band SWR improved significantly with this localized inductance to compensate for the boxs capacitance. I mentioned in the reference article that the metric A/l captures the geometry, the larger it is, the fewer turns for same inductance / impedance. So, how to construct an end-fed half wave antenna? It is very hard to know what will be the best solution for a given antenna installation if you want to hit all of the bands exactly. The change in heat content in the box as it cools can be written: where and are the ambient temperature and heat content respectively. Refurbishing aluminium antenna parts affected by weather / corrosion. The finished tran, End Fed Half Wave (EFHW) Antenna Upgrade Part 1 - The Matching Transformer. It is quite difficult to satisfy both requirements of achieving proper impedance ratio and resonance of the tank circuit at each tap of the inductance. Change), You are commenting using your Twitter account. This happens to place the coil near the peak of a current maximum for the 20m band, which coincidentally appears to have significantly improved the match on that band. This can then, fed with coaxial cable, in many cases be . What seemed to work best was to concentrate the turns on the tap-side of the secondary winding, using several (#28) wires in parallel for the primary turns such that they covered about half of the underlying secondary winding. If not a lightning strike, I will write an article about the experience as well. Radio Transceiver S-Meter Pitfalls to avoid, Atmospheric impact on VHF Radio Propagation, Terrestrial VHF Radio Signal Coverage LOS, Terrestrial VHF Radio Signal Coverage BLOS, HF Surface Wave Propagation (Ground Wave). The bottomline, your putting the relationships of 1) Toroid windings and to measure their inductance together with 2) the required capacitance calculation is exactly what I needed to move forward with my specific design plans. Thirty turns #28 are wound on the two FT114-43 cores. The antenna is up. Ha elolvasod alapszablyunkat s a benne lertakat elfogadod, akkor nincs ms teendd, mint a ha5kdr@ha5kdr.hu email-cmen, vagy egy klubnapon jelentkezni nlunk! I used four parallel #28 wires (not twisted) for the primary. 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. Hence, even operating at 1000W on the 160m band, the cores would not saturate with the 5-turn primary. There is much more that can be written about this antenna and its matching, but that was not my aim. If you need to change it, is necessary to recalculate the secondary turns, and the resonance frequency needs to be adjusted also. One of the many confusing terms used in Workers' Compensation, "IME" stands for Independent Medical Evaluation or Independent Medical Examination. Best regards and thanks again for your comment. The slim coil is torpedo shaped to prevent it being snagged in trees when deployed in 'the great outdoors'. If you stare at the above frequency sweeps you will discover a few things. However, it has its idiosyncrasies. I also will ask, why didnt it work for you. That is an end-fed, but very different then the half wave construction. This antenna is only 15m long using 2 loading coils. Nevertheless, I will also describe, how it is designed, if one decides to embark on building it for different bands. = 1/30.e6 = 33 nS. Above, 3t on the primary delivers Gcore<0.002S. The effect of the capacitor is very apparent for 17 meters and above, flattening and lowering the SWR curve through 10 meters. Wow, Gary! In the case of the EFHW 49:1 transformer, the major shortcomings of the most popular current designs are excessive leakage inductance and poor heat transfer from the ferrite material to the environment. That does not seem inconsistent with the expectation calculated above of about 10% core loss at 3.6MHz. The EFHW transformer box from outside. It is much easier to wait ~2, know that you are going to see about 86% of the temperature change you would see if you waited until time infinity, and just make a simple correction. Note: Crosswalk CAA administers the LIHEAP in Franklin, Jefferson, and Williamson Counties. An example is shown in this figure of a 49:1 transformer with a 100 pfd capacitor in the primary side of the transformer. Do your own experiments with your own set up, 2019 - 2022 by Dan Koellen AI6XG. Commercial Coils, Inc. 213 Chesterfield Industrial Blvd Chesterfield, Missouri 63005. Hence, there is no optimum single-fit solution. I have been offered input VSWR curves for such a configuration, and they are impressive but VSWR curves do not address the question of loss / efficiency. Nagyon j ez a cikk. All Rights Reserved. P.S. (LogOut/ i liked it a lot, you give good ideas, many thanks. But systems that work better increase the prospects of contacts. This is based on random lengths of the antenna, which is transformed with the un-un into a medium-ohmic impedance range with reactive components. The final turns ratio turned out to be 3:29. There is no substitute for playing with the analyzer, trimming the wire, adjusting the compensation coils, etc., and going through the process for a few iterations to get the multiband antenna to work well for you as you have it installed. This will yield the minimal capacitance of the variable capacitor. For the transformer, a T130-2 toroid will be sufficient, on which we wind the seconder with multiple taps, as shown in the below table. Ive spent some time on digital modes over the last week and and my signal reports seem very similar to the pre-80m-extension period, which is good, and I am getting out well past 1000 miles on 20, 40m and 80m digital. I installed an eyebolt on one end as a pull-point, and a BNC connector on the other. The antenna is effective and the materials and construction are of a very high quality. The 6-turn loading coil lowers the resonant frequency into the CW portion of the 80 meter and higher bands. However, from the measurements we made on the self resonance frequency, we know that most of this capacitance is right at the output of the transformer and not internal to the windings. A method for estimating the impedance of a ferrite cored toroidal inductor at RF. (LogOut/ He was afraid that being, Inverted V Antenna - A popular Dipole variant, The Center-fed Half-Wave Dipole Inverted V Antenna An Inverted V antenna is a very popular variant of the standard horizontal dipole. EFHW Antenna Frequency Compensation Lead 5,144 views Jan 20, 2019 188 Dislike Share Save Steve Ellington 9.92K subscribers 8 inches of wire attached to the antenna post can lower the frequency. The SWR for 30 meters, 1.05:1, was the lowest of all three antennas since the transformer was tuned for impedance match at 30 meters. I have seen and read quite a few reports of making this antenna, and some got away no problem with the 110uH when they came to set up and adjust the antenna, others needed to tweak their coil turns. I checked the inductance again to make sure this hadnt been overly affected, and it remained unchanged at 109.8H, good enough! See the second completed tuner depicted below. Show more. Accordingly, calculate the capacity for the resonance at the highest frequency to be covered with the highest inductivity taken in consideration. I have an EFHW and the SWR is acceptable on all the bands with the exception of the WARC bands which is to be expected since the harmonic relationship is different. Thanks again Jim. It should be no surprise that 80pF is close to optimal. The coil uses 26 AWG (27 SWG) enamelled copper wire close wound on a machined plastic former. I may try to bring down the 20, 15 and 10m bands at some point, either with a small coil 2m from the feed point or with a short section of wire as a compensation lead added at the feed point as shown in the video below from Steve Ellington. Krem, rja le, mi a krdse. The technical storage or access that is used exclusively for statistical purposes. Because of the turns ratio N, the secondary capacitance will appear N2 larger at the primary and will resonate with the primary magnetizing inductance. Thermal gasketing between the cores and the aluminum heat sinks could help a lot, as would a single piece of aluminum rather than the stack up of thin sections I used. Disclaimer | Privacy Policy | Cookie Policy | Terms of Use. There are many resources online that explain the details better than I can, so Id suggest doing your own research if youd like to build one for yourself. Being a more efficient design that some, it might result is a wider VSWR excursion that those others as transformer loss can serve to mask the variations in the radiator itself. The slim coil is torpedo shaped to prevent it being snagged in trees when deployed in 'the great outdoors'. This is why we need the impedance transformer from the 50 coaxial feed-line to the several kilo-ohm antenna connections. I would mention first its ease of installation. The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes. No wire counterpoise is used to reproduce the SOTA setup. This could be achieved by increasing the spacing of the windings, hence reducing the interwinding capacitance. I installed a QRP SWR meter into the tuner that makes tuning very handy. It is important that resonance may be achieved at each tap of the inductance. As you stated early in your posting, I also have found 99.99% of all posting on the internet tell you WHAT they did.not HOW they determined the specific design criteria. Update: Full size 132ft EFHW For one month I replaced the 66ft wire and loading coil and replaced it with a full 132ft of wire, connected to the FT240-43 balun. Even at 15W the voltage at the ends may reach 100-200V. A tutorial on estimating the impedance of a toroidal ferrite cored inductor for radio frequencies, Pulse test of a Hantek 6204BD 4 channel 200MHz USB DSO and supplied probe. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Enter your email address to subscribe to this blog and receive notifications of new posts by email. Being end fed, it needs a transformer to transform the higher impedance of the wire to the 50ish ohms the radio is expecting. For a quarter wave that is about 8 nS. It not a loading coil. The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network. How far could it possibly reach? I decided to push for best efficiency with a 5-turn primary. The bridge than will measure zero voltage across the bridge, and the LED will turn off. I can give a link if you need. CG K/ J/ S/ B to 4-20mA 0-1800 Celsius Thermocouple Converter TC Input 4-20mA Output Head-mounted Temperature Transducer first impressions, Some wisdom that shapes articles on this site, Designing high performance VHF/UHF receive systems, A new impedance calculator for RF inductors on ferrite cores, Calculate ferrite cored inductor (from Al), Calculate VSWR and Return Loss from Zload (or Yload) and Zo, https://owenduffy.net/files/EstimateZFerriteToroidInductor.pdf. This article will not address that antenna type. Compensation. There are two aspects, however that we need to consider: Lets begin with the transformer. inductance as one FT240-43 and is able to withstand 1kW 50/50% duty cycle with help of a cooling fan. Thanks in advance, good health for you in these times, Next, I started winding the transformer. The EFHW's SWR will be affected by height above ground, type of ground, feed line interaction, and any nearby conductive surfaces. I then used a piece of heat shrink on the outside to hold everything in place. With such a switch, it is impossible to forget to switch back to operational mode. The biggest uncertainty in these measurements was the actual power level used. The End-Fed Half Wave Antenna a bit Differently, The End-Fed Half Wave Antenna a bit Differently Coventry Amateur Radio Society, Ismerje meg a hozzszls adatainak feldolgozst, 40 M R/7E azaz a kirlyi ejternysk rdillomsa, jra megy az SSTV tjtsz 144,500 MHz-en. The VSWR plots below show results from the same transformer tested on the bench with minimal output capacitance, with a primary compensation capacitor, either 100pF or 27pF included, with the transformer installed in its aluminum box including antenna connector feedthrough, and with the transformer with an 18 clip-lead on the antenna output. Ive been wanting to get back into radio stuff for a while now, but the only antenna that I have up now is a 40 meter dipole. A/l for the chosen core is 3.5 times that of a FT82-43 yet it is only 1.6 times the mass. Thank you for an interesting and informative read. Because of the division of power between the 3220 resistor and VNA input, there is effectively an attenuator of -10*log(50/(50+3220))=18.16dB, so |S21| has a component due to this division. The high frequency performance was extraordinarily sensitive to anything that could add capacitance to the output lead. 'Capacitor flattens SWR at higher frequencies' - WA7ARK. Calculate the capacity for the resonance at the lowest frequency to be covered with the lowest inductivity taken in consideration. Toll Free 800-532-2645 636-532-1523 Fax: 636-532-8259. This animated illustration shows the harmonically related current conditions that exist on the EFHW antenna wire on various HF bands. My favorite SOTA antenna is the End-Fed Half Wave Antenna. Fig.1 - Withdraw the radiating element carefully to avoid damaging the matching components A few years ago I bought a secondhand Diamond X50 dual band (144/430) antenna at a radio car boot sale. I have also had SSB QSOs in Europe, USA and Canada on 20m so havent seen any degradation in performance on that band. These, in turn, are instrumental Read More, Learn CW Morse Code Lesson Set 2 This is Lesson Set -2 in our multi-part series of CW Morse Code hands-on tutorials where we will introduce numerals and a few important punctuation marks as Read More. For Jackson County, please call Western Egyptian Economic Opportunity Council, in Steeleville, at (618) 965-9031. I have been using a 40m End-Fed Half Wave (EFHW) antenna very successfully for the last few months and I wanted to extend the design to multi-band whilst avoiding the need to take a . You can achieve this inductance with half a dozen turns of the antenna wire tied in a small coil. There's seemingly conflicting information out there, such as on QRZ the consensus seems to be to either use no choke on the coax, or choke it some ways away from the feedpoint - WA7ARK recommends .07 wavelength, which is about 9' on 40M. The usual problems of having the multiple band resonances all line up appear here with the end-fed design, similar to the same issue with off-center-fed designs. y73s de Michael DL9SKY, Visszajelzs: The End-Fed Half Wave Antenna a bit Differently Coventry Amateur Radio Society, Az e-mail cmet nem tesszk kzz. SWR for 80-10 meter EFHW with no capacitor, SWR for 80-10 meter EFHW with 100 pfd capacitor, The above data from K1RF shows that the SWR for 20 meters (my dark red markings -, I hope to do more experiments with single and multi band EFHW antennas above 20 meters - stay tuned, 40 meter and 20 meter (full wave) SWR with no cap. Change), You are commenting using your Facebook account. Let us touch on some necessary theory to begin with. It is likely that next time the tuning may be set according to the already found positions, and it will not be far off, requiring only slight adjustment. It depends on the selection of the inductance and the capacitor values. The real power limit will be core heating. However, a key restriction is its 25W power rating, due to the small matching transformer. A design by VK3JEG is only 66-ft. long, about the size of a 40m dipole. However, to minimize capacitance, you want to spread turns and keep windings apart, so what is the right approach? Note the material 43 hysteresis curves shown below for 25 C and 100 C has a smaller open area (and hence lower losses) at the higher temperature. Once completed and tape-wrapped, I applied a layer of liquid electrical tape over the surface and the interior wire connections, ready to go outdoors. In this case C~5pF and Z~2450 suggests that the inductance needed should be about 30 H. It uses a coil as a compensation unit, and no counterpoise. I used my IC-751As power meter and an in-line Siliconix power meter as well as a voltage probe on the feed cable. <> A krdsem az, hogy a knyv elrhet esetleg pdf-ben is? Although the original loading coil is very well engineered, I thought I could make a more efficient version given that I did not need to make it 'trail friendly'. Intro EFHW Compensation Coil Experiment Steve Ellington 10.3K subscribers Subscribe 29K views 4 years ago The little coil helps place the EFHW resonance points where we want them. I got the, http://pa-11019.blogspot.com/2012/04/149-transformer-for-endfed-antennas-35.html, End Fed Half Wave (EFHW) Antenna Upgrade Part 2 - The Loading Coil. The band compensating inductor placed on the wire is another story. It performed well on both the 2m and 70cm bands. It is hard to wait an infinitely long time for the box to equilibrate to a given power level. I used the coil inductance calculator at 66pacific.com and after a few tries came up with 83 turns over a length of about 83mm as shown below. I started with a small piece of PVC pipe and drilled a few holes in it to run the wire through. Jos van den Helm's (PA1ZP) article published in Radcom: Fig.1 - Withdraw the radiating element carefully to avoid damaging the matching components A few years ago I bought a secondhand Diamond X50 dual band (144/430) antenna at a radio car boot sale. End-Fed antennas are useful in many ways, includes easier mounting of cable at one end (freeing the antenna from unnecessary weight of cable) & antenna maintenance in future. Wire antennas with an Un-Un-transformer 1: 9 have become more and more popular. An end fed half wave antenna, or efhw, is a variation of a half wave dipole, but it is fed from one end. During portable operations, I noticed that I forgot the toggle switch in the tuning position, just to discover that no one calls me back to my relentless CQ-ing. But before we do, let us look at the insertion and transmission loss that the VNA is reporting. The procedure was to run for around 30 minutes starting from the box cool at ambient temperature. When you are discussing a distributed capacitance, it is difficult to know exactly what you are measuring. It was difficult to work out where it was coming from but I found that it was more noticeable when it was windy outside. I used a section of 40mm external diameter PVC waste pipe and 1mm diameter enameled magnet wire to make the coil. At equilibrium, the heat leaving the box due to cooling will exactly equal the heating power input. There could be any number of reasons for that, where I put the bends in the wire, the location of tree branches, etc. Un-Uns for Endfed-Antennas (EFHW) by DK7ZB. 2006. I strung up a nominal 80m half-wave antenna wire into the trees, snaking it through the open screen door to the work bench where I was doing the tests. A 100pF silvered mica was connected in shunt with the transformer primary. It is not necessary to calculate the above; the results are sown in the following table. The comparison is done on 4 bands - 10m, 20m, 40, and 80m. The coil uses 26 AWG (27 SWG) enamelled copper wire close wound on a machined plastic former. Firstly, lets estimate at 3.6MHz minimum number of turns to ensure that magnetising conductance is less than about 0.002S (for better than 90% core efficiency). It is all about getting the heat out. The overlaid VSWR plots are shown below. Since it is a EFHW and not a non-resonant end fed, the wire length for 40m is about 67 feet. This is perhaps one of the most hotly debated rookie topics in.
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