Winding efhw transformer

This is a hand made EFHW Antenna with a built in 49:1 Transformer. This is incredible for POTA, SOTA and other portable/field operations. Setup in any end fed configuration you like. Please let me know if you are interested in a different configuration. With wire, without, 20m, 40m, etc.Built using a single Fair-Rite T140-43 core with 49:1 winding and 2kv 100PF capacitor. The antenna comes with a BNC connector, screw top post for the antenna wire and 10.25m of lightweight antenna wire. The total weight of the transformer, winder with 10.25m antenna wire is approx. 135gm +-. Coax is 50 ohms EFHW is 2500 ohms,,,Humm 49:1 unun is almost 50:1 transformer 2500ohms/50ohm transformed to 50 ohms. That is not all, once the transformation is done at the primary frequency it also transforms the miss match as one varies the frequency of the rig. This decreases the mismatch with varying frequency by 50 times. Since may of all of these EFHW antennas use the coax as a counterpoise, what is the ... I found one that instead of a fully isolated transformer, it used an auto transformer design so, at least in my mind, there was a complete circuit. ... So I started taking winding off and the whole thing started to behave. I got down to 10 turns total and no ...The hole in the center is too small to fit over a 1/4 inch rod. The IF transformer will be made by sliding the bobbins over 1/4 inch plastic rod. These will not fit the coil winder or the finished transformer. I experimented with drilling out the center hole and enlarging the small holes on the sides to 1/8 inch. May 01, 2021 · Step 3: Cut 74 inches of 14ga speaker wire for the 80m portion and install ring terminal then attach to coil with machine screw and nut. Prune far end of 80m wire for middle of desired portion of the 80m band then install ring terminal connector. I use #36 braided nylon decoy line to suspend the antenna, but you could use any kind of cordage as ... The SWR is high (over 3:1 ) and a reflection of 25% or more will dissipate on the transformer core which can lead to the destruction of the same. If you prefer a 3.8-4MHz sideband (SSB) operation, get an EFHW-7510-2K+ model which has low SWR on 75M and maintains the low SWR on other bands just like the EFHW-8010 model does. So you have an EFHW sloper.... perfectly legitimate configuration. GREAT that it works so well on 20 and 40. ... It uses an Amidon FT240-43 Toroid and wound with 1.0mm copper winding wire. ... for that specific kit but MyAntennas places a coil (5 turns of the antenna wire around a 2" dia form) 78" from the transformer. I believe the coil helps ...I've built a couple 49:1 and 64:1 EFHW transformers and have decided I want to build a perfect camping end-fed half-wave. An antenna that can handle 100w digital with a 50% duty cycle and roll up to fit in your pocket. My plan is to use 67ft of 20ga wire with a 49:1 transformer that uses 3x FT140-43 cores and 100pf of capacitance.More coax is good in this case because its more antenna to radiate. If you want an end fed for 160m that actually works well you would go with a full 1/2 wavelength of wire (about 250ft) fed with a transformer that has a very high impedance output to match the 1/2 wave end fed. Several companies make the transformer and complete antennas and if ...End-fed, half-wave antennas (EFHWs) are a half-wavelength long and are resonant antennas on the band of interest. They use some kind of matching network to trasnsform the very high impedance at the end of a half-wave wire to about 50 Ω. Generally, they are not usable on bands for which they are not a half wavelength long.Jan 26, 2012 · 18 kV to 13.8 kV, 4.16 kV sounds like a power plant auxiliary transformer fed from the 18 kV generator bus to supply in-plant generator loads. The three winding transformer saves money and space with only one foundation, one HV input, one HV circuit breaker or tap. Disadvantages: Since it is custom, it is hard to find a replacement if it fails. Oct 03, 2014 · 3. Any transformer connected to 240V AC has to have sufficient inductance in the primary so that it isn't taking a large magnetization current - just think of the primary and ignore the secondary for now - imagine you are only making an inductor to connect to the AC - you don't want it taking ten amps just by itself. We will be able to determine which is the center-tap when we take voltage readings as outlined later. The chart below shows typical readings for a transformer with a primary, high-voltage, 5-volt rectifier, and 6.3-volt filament windings. Winding. Resistance. Primary. 4 - 8 ohms. High-voltage. 200-400 ohms. H-V center tap. Unique Models Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Current delivery time 7-10 days. Learn More Shipping: Calculated at Checkout $95.95 Select Configuration: Required Model 49131e - Eyebolt for Antenna Connection Model 49131sw - Stud with Wing Nut for Antenna Connection Next availability TBDA bifilar-wound coil is one that contains two closely spaced, parallel windings. This can be achieved by winding coils using two insulated conductors. Some bifilar-wound coils have adjacent coils in which the turns are arranged so that the potential difference is magnified (that is, the current flows in the same parallel direction).So you have an EFHW sloper.... perfectly legitimate configuration. GREAT that it works so well on 20 and 40. ... It uses an Amidon FT240-43 Toroid and wound with 1.0mm copper winding wire. ... for that specific kit but MyAntennas places a coil (5 turns of the antenna wire around a 2" dia form) 78" from the transformer. I believe the coil helps ...BalUn & UnUn Kits. 1:49 Impedance transformer End fed antenna 100 Watt DIY kit. € 22,00 Incl. VAT. Complete 1:49 Impedance Transformer DIY kit for End Fed antenna's. 100 Watt, with solid tensile stools, all stainless steel. With a handy fixing plate for the toroid, so no longer necessary for gluing. This kit includes everything for a 1:49 ...Jun 06, 2020 · The primary winding capacitor is not needed for EFHW antennas that operate as a single half wave for 20 meters and below. For 15 meters and above a capacitor should be considered, insertion loss is decreased for transformers with a primary winding capacitor. Winding the matching toroid Using the enamelled copper wire wind 13 turns on the toroid. Each time the wire passes through the toroid counts as one turn. This is the secondary winding. Don't overlap the turns, but keep them quite close together - we may need to space the windings out later when we get to the tuning phase.BUILD INSTRUCTIONS FOR 49:1 UNUN IMPEDEDENCE TRANSFORMER: 1. PREPARING THE TOROIDS AND WIRE Superglue 2 toroids together. Wait a few minutes for glue to set. Wrap toroids with glass electrical tape. Twist the short and long wires together starting at an end of each wire. Continue twisting the entire length of the short wire.The net abounds with articles on broadband transformers (ie untuned) for matching End Fed Half Wave (EFHW) antennas to 50Ω. One of the aspects that is common to most designs is that the turns of the primary winding are wound 'bifilar' with the start of the secondary winding, indeed the twist pitch is often very short and articles often go into detail on how to make this magic thing.Nov 12, 2017 · The net abounds with articles on broadband transformers (ie untuned) for matching End Fed Half Wave (EFHW) antennas to 50Ω. One of the aspects that is common to most designs is that the turns of the primary winding are wound ‘bifilar’ with the start of the secondary winding, indeed the twist pitch is often very short and articles often go into detail on how to make this magic thing. K6ARK specifies 3 primary and 21 secondary windings. This means 21/3=7 and 7x7=49, so he's got you winding a 49:1 transformer. Using 2420 ohms (2 half watt resistors, one 2.2k and one 220 ohm) with my big 49:1 transformer, I get acceptable SWR under 3:1 on 29 meters, and under 1.5:1 on 80 meters. Resistance shows 36.something ohms on 20 meters. 1) More primary turns and primary inductance improve the transformer efficiency and low end performance. 2) Winding capacitance and leakage inductance, especially present as you increase the number of turns, limit the high frequency performance. 3) Total losses are approximately independent of core volume.Unique Models Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Current delivery time 7-10 days. Learn More Shipping: Calculated at Checkout $95.95 Select Configuration: Required Model 49131e - Eyebolt for Antenna Connection Model 49131sw - Stud with Wing Nut for Antenna Connection Next availability TBDThe transformer configuration produces an inductive component at the 3rd tap wire. A reactance, Xs, is in series between the source and the primary winding to provide the means to compensate for this. This is a core-less air transformer (or "air core" if you like) just in case that isn't obvious. That series reactance is most often a ...All commercial EFHW antennas sold are nothing but random chunks of wire and some form of balun. It's incredible that some manufacturer's are charging $250 for these very compromised antennas. You can make your own for about $15, or better yet put up a proper 1/2 wave dipole. 5. Fixed Impedance Ratio Lower Leakage Inductance End-Fed Half-Wave Transformer by Daniel Marks, KW4TI February 28, 2017 This document describes and characterizes a winding pattern for an autotransformer suitable for an end-fed half-wave antenna. These transformers must match loads of 2000-4000 ohms which is a The transformer consists of 2 primary windings and from 14 secondary windings. This gives a ratio of 1 to 7. The voltage is therefore seven times higher than the source voltage and the current is seven times lower than the source current. This results in an impedance transformation of 7 x 7 = 49. That increases the impedance of 50 Ohm by a ...Optimized winding technique results with winding capacitance and leakage inductance canceling out. Referring to the photographs above. Wind the four turn primary/secondary winding. Green wire in the photograph. Each wrap through the core equal one turn. Solder the secondary wire to the primary/secondary wire. Red wire in the photograph. Feb 04, 2019 · The transformer configuration produces an inductive component at the 3rd tap wire. A reactance, Xs, is in series between the source and the primary winding to provide the means to compensate for this. This is a core-less air transformer (or “air core” if you like) just in case that isn’t obvious. That series reactance is most often a ... May 01, 2021 · Step 3: Cut 74 inches of 14ga speaker wire for the 80m portion and install ring terminal then attach to coil with machine screw and nut. Prune far end of 80m wire for middle of desired portion of the 80m band then install ring terminal connector. I use #36 braided nylon decoy line to suspend the antenna, but you could use any kind of cordage as ... USA. www.dtbradio.com. Sep 24, 2020. #1. I've been puttering around with end-fed half-wave antennas for 40 through 10 meters (concentrating on 40 for now), and have had trouble coming up with a good match-box design. I've tried different ideas from an array of online sources ranging from auto-transformers in various turns ratios to basic L ...Tertiary winding is provided in electrical power transformer to meet one or more of the following requirements-. It reduces the unbalancing in the primary due to unbalancing in three phase load. It redistributes the flow of fault current. Sometime it is required to supply an auxiliary load in different voltage level in addition to its main ...Since may of all of these EFHW antennas use the coax as a counterpoise, what is the ... I found one that instead of a fully isolated transformer, it used an auto transformer design so, at least in my mind, there was a complete circuit. ... So I started taking winding off and the whole thing started to behave. I got down to 10 turns total and no ...Mar 15, 2020 · ICOM IC-V3500 – 144 MHz FM – 65 W. July 14, 2022 No comments. ICOM IC-V3500 65 W Powerful RF Output Power The Icom IC-V3500 is a rugged 2 m mobile transceiver providing powerful 65 W* of output power. Built using a single Fair-Rite T140-43 core with 49:1 winding and 2kv 100PF capacitor. The antenna comes with a BNC connector, screw top post for the antenna wire and 10.25m of lightweight antenna wire. The total weight of the transformer, winder with 10.25m antenna wire is approx. 135gm +-. A Simple 4 band EFHW for 40,20,15, and 10 meters. I like the EFHW for portable use because it is quick to deploy - unlike a quarter wave vertical, it doesn't require radials and unlike a dipole it's fed at one end. I have been trying out variations of the EFHW (end fed half wave) antenna for several years.These have included a 3 band trapped ...The hole in the center is too small to fit over a 1/4 inch rod. The IF transformer will be made by sliding the bobbins over 1/4 inch plastic rod. These will not fit the coil winder or the finished transformer. I experimented with drilling out the center hole and enlarging the small holes on the sides to 1/8 inch. Winding. Jordan Transformer can remanufacture and upgrade your existing transformer with new copper windings and a custom-made high-density pressboard insulation package. The short circuit design is upgraded to the latest standards. Your new coils are hand-wound in a climate controlled clean room by our team of expert winders. To fix this, EFHW antennas need a transformer to match impedances. When used to match impedance between a balanced antenna, like a dipole, and an unbalanced feedline, like coaxial cable, these are ...The net abounds with articles on broadband transformers (ie untuned) for matching End Fed Half Wave (EFHW) antennas to 50Ω. One of the aspects that is common to most designs is that the turns of the primary winding are wound 'bifilar' with the start of the secondary winding, indeed the twist pitch is often very short and articles often go into detail on how to make this magic thing.Below is a visual representation of a way that works properly. To get a 35 uH coil around a 19 mm PVC pipe, one can use 80 windings of 0,75 mm (0,44 mm2) winding wire. For the 110 uH coil one can make 170 windings with 0.5 mm (0.20 mm2) winding wire. For deviating coils or a different diameter of winding wire, the following tool exists. 2 Definition of the Described EFHW Antenna In this document, I refer to an EFHW antenna that is a resonant half-wave dipole, fed from its (near) end, and consists of a single radiator wire.The primary winding capacitor is not needed for EFHW antennas that operate as a single half wave for 20 meters and below. For 15 meters and above a capacitor should be considered, insertion loss is decreased for transformers with a primary winding capacitor.This is a hand made EFHW Antenna with a built in 49:1 Transformer. This is incredible for POTA, SOTA and other portable/field operations. Setup in any end fed configuration you like. Please let me know if you are interested in a different configuration. With wire, without, 20m, 40m, etc. May 27, 2020 · The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1 The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. He had put together 49:1 impedance transformer kits for end-fed halfway antennas. Five hams came with their kits and learned to wind primary and secondary windings on a toroid core. Christie KO4NCL, Fred KN4ZME, Bob AJ4RS, and Jack KY4EA wound their first transformers. Sep 24, 2020 · USA. www.dtbradio.com. Sep 24, 2020. #1. I've been puttering around with end-fed half-wave antennas for 40 through 10 meters (concentrating on 40 for now), and have had trouble coming up with a good match-box design. I've tried different ideas from an array of online sources ranging from auto-transformers in various turns ratios to basic L ... May 13, 2015 · MEF-330-1K Multi Band End Fed Half Wave Antenna Transformer. This is an End-Fed Half Wave antenna (EFHW) Transformer for frequencies between 3 and 30 MHz. To use it at any frequency in this 3-30MHz spectrum just add half wave long wire for the frequency of your interest. Benefit of the EFHW antenna is that it will be resonant on harmonic ... Lets apply the method laid out at PD7MAA's BN43-202 matching transformer for an EFHW. The best Fair-rite data I can find quickly is a chart of the impedance of a one turn winding. Scaling from this graph, Xs is close of 35Ω at 7MHz, so lets used that to derive some basic parameters for the core. Firstly, lets find the permeability of #61 at 7MHz.This is due, in part, to the ratio balancing of the transformer's turns (windings), and to a few complex reactance and other physics attributes that I won't try to cover here. Additionally, the unun will eliminate (virtually) all "common mode" currents on the feedline. This is important for eliminating the pickup of local electrical noise from ...This is a hand made EFHW Antenna with a built in 49:1 Transformer. This is incredible for POTA, SOTA and other portable/field operations. Setup in any end fed configuration you like. Please let me know if you are interested in a different configuration. With wire, without, 20m, 40m, etc.The hole in the center is too small to fit over a 1/4 inch rod. The IF transformer will be made by sliding the bobbins over 1/4 inch plastic rod. These will not fit the coil winder or the finished transformer. I experimented with drilling out the center hole and enlarging the small holes on the sides to 1/8 inch. Winding the matching toroid Using the enamelled copper wire wind 13 turns on the toroid. Each time the wire passes through the toroid counts as one turn. This is the secondary winding. Don't overlap the turns, but keep them quite close together - we may need to space the windings out later when we get to the tuning phase.The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1Nov 13, 2012 · With EFHW antennas using an adjustable matchbox there is a great willingness to use the tuning of the matchbox to “fix” a detuned wire or a wrong length wire. IF you do that its not an EFHW as its now a random wire with a random wire tuner and one must use a ground or counterpoise to work against. Below a picture of the transformer with 2 resistors connected acting like a load for SWR control with a VNA. More details about construction can be found on PA3HHO Web page [4] and in the Facebook group [3] The coupler is the original EFHW adapter solution and is build to allow a tuning on any frequency with a bit more "fine tuning".Jul 27, 2021 · July 27, 2021 e73m. Ever since March 2015 when we started to market the High Ratio/Wideband transformers for EFHW antennas the work on R&D (Research & Development) never stopped. The number of limitations in the design of a 49-81:1 ratio of impedance transformation over a large HF frequency spectrum (1-30MHz) was challenging and final designs ... One way to make the Fuchs antenna multi-band, is to add selectable taps on the primary and/or the secondary side of the transformer. Further "tuning" can be done with a variable capacitor across the selected tap of the antenna-side winding of the transformer and the "bottom" of that winding. Ref. 1.The SWR is high (over 3:1 ) and a reflection of 25% or more will dissipate on the transformer core which can lead to the destruction of the same. If you prefer a 3.8-4MHz sideband (SSB) operation, get an EFHW-7510-2K+ model which has low SWR on 75M and maintains the low SWR on other bands just like the EFHW-8010 model does. Feeding the EFHW wire with a 1:50 – 1:60 impedance transformer (unun) instead of an EFHW tuner incorporating a capacitor makes it far less sensitive to the environment stopping the SWR from varying wildly. 2. Adding super lightweight Pico Traps from SOTABeams gives multiband performance without the need for a tuner and without the need to ... The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. have never seen before. A small and efficient broadband transformer is used to match the impedance of this EFHW antenna to a 50Ω coaxial cable. The document starts with the definition of the described EFHW antenna system, the author’s personal portable antenna requirements, the history of choosing and developing EFHW TOROIDAL TRANSFORMER WINDING 12 •Use a 16:2 turns ratio (8:1) •Impedance ratio is 64:1 •Best to twist wires together going to ground (the 2 turn section) for lower noise •The 2-wire section is a bifilar winding •Wrap the toroid in PTFE (plumber's) tape to prevent arcing if using bare or enameled copperThe transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. Sep 02, 2020 · Review of the Packtenna Antenna systems in ...Jan 26, 2012 · 18 kV to 13.8 kV, 4.16 kV sounds like a power plant auxiliary transformer fed from the 18 kV generator bus to supply in-plant generator loads. The three winding transformer saves money and space with only one foundation, one HV input, one HV circuit breaker or tap. Disadvantages: Since it is custom, it is hard to find a replacement if it fails. In order to evaluate the choking characteristics of the "red" toroids, I prepared two chokes by winding 12 coils of RG-58 on a iron powder T200-2 toroid and a ferrite FT240-43 one. ... They say the 43 material is the stuff to use for ferrite 49:1 or 4:1 for Delta Loop or EFHW balun transformers… it'll work but it's not the best stuff. ...Sep 24, 2020 · USA. www.dtbradio.com. Sep 24, 2020. #1. I've been puttering around with end-fed half-wave antennas for 40 through 10 meters (concentrating on 40 for now), and have had trouble coming up with a good match-box design. I've tried different ideas from an array of online sources ranging from auto-transformers in various turns ratios to basic L ... Below a picture of the transformer with 2 resistors connected acting like a load for SWR control with a VNA. More details about construction can be found on PA3HHO Web page [4] and in the Facebook group [3] The coupler is the original EFHW adapter solution and is build to allow a tuning on any frequency with a bit more "fine tuning".2 turns primary and 14 turns secondary. The crossover counts as a turn. Generally if the SWR is too high on the higher bands, remove a turn and if too high o... The antenna system consists of a 40-10 EFHW (~60' Wire matched to a QRPGuys EFHW transformer mounted on a DIY wire winder cut from a yard sign), 5 aluminum tent pegs, 2 pieces of shock or bungee cord for tying off the antenna ends, a 25' BNC terminated RG-174 coax, and a 14-1/2 ft fiberglass fishing pole with DIY collar and guy lines. Optimized winding technique results with winding capacitance and leakage inductance canceling out. Referring to the photographs above. Wind the four turn primary/secondary winding. Green wire in the photograph. Each wrap through the core equal one turn. Solder the secondary wire to the primary/secondary wire. Red wire in the photograph. Dec 27, 2021 · An end fed half wave antenna, or efhw, is a variation of a half wave dipole, but it is fed from one end. Being end fed, it needs a transformer to transform the higher impedance of the wire to the 50ish ohms the radio is expecting. There are many resources online that explain the details better than I can, so I’d suggest doing your own ... Step 1: Wrap the green wire around the toroid seven times, feeding the first wind under the toroid. Step 2: Wrap the yellow wire around the toroid seven times, feeding the first wind under the toroid. Step 3: Wrap the blue wire around the toroid three times, feeding the first wind under the toroid.EFHW Transformer –alternative designs •The 14T secondary winding can use #18 wire since its current is low. A separate primary winding of 2T #14 wire near the center of the 14T coil will handle the higher current, 5.5 amp at 1500W •See CQ Magazine December 2021: A Deep Dive Into End Fed Half Wave Antennas by Bob Glorioso, W1IS, and Bob Rose, The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. Ratio is for 2450 Ohm (1:49 transformer) Tail current is only 15% of peak in wire Not a big stretch to cut off tail wa7ark 24 EFHW as a multi-band antenna EF resonates on all harmonics, Resonance not exact integer multiples Requires Compensation coil, about 6ft from transformer Aligns the SWR dips on harmonics Coil makes it "longer"Being end fed, it needs a transformer to transform the higher impedance of the wire to the 50ish ohms the radio is expecting. There are many resources online that explain the details better than I can, so I'd suggest doing your own research if you'd like to build one for yourself. You can start with the links below. http://www.aa5tb.com/efha.htmlMay 13, 2015 · MEF-330-1K Multi Band End Fed Half Wave Antenna Transformer. This is an End-Fed Half Wave antenna (EFHW) Transformer for frequencies between 3 and 30 MHz. To use it at any frequency in this 3-30MHz spectrum just add half wave long wire for the frequency of your interest. Benefit of the EFHW antenna is that it will be resonant on harmonic ... The net abounds with articles on broadband transformers (ie untuned) for matching End Fed Half Wave (EFHW) antennas to 50Ω. One of the aspects that is common to most designs is that the turns of the primary winding are wound 'bifilar' with the start of the secondary winding, indeed the twist pitch is often very short and articles often go into detail on how to make this magic thing.I’ve built a couple 49:1 and 64:1 EFHW transformers and have decided I want to build a perfect camping end-fed half-wave. An antenna that can handle 100w digital with a 50% duty cycle and roll up to fit in your pocket. My plan is to use 67ft of 20ga wire with a 49:1 transformer that uses 3x FT140-43 cores and 100pf of capacitance. Although this does work as stated I have found that twisting the primary winding does slightly better on the high bands. It's your choice.Please see the late... The net abounds with articles on broadband transformers (ie untuned) for matching End Fed Half Wave (EFHW) antennas to 50Ω. One of the aspects that is common to most designs is that the turns of the primary winding are wound 'bifilar' with the start of the secondary winding, indeed the twist pitch is often very short and articles often go into detail on how to make this magic thing.2. Using the EFHW for 20m at GB0CMS 3. EFHW featured in "Stealth Antennas" 3. More about earthing/ground radials 4. Using the 20m EFHW on 10m 5. Detailed construction notes 6. Turning the EFHW into a four-band antenna 7. The 20m-17m-15m three-band trapped EFHW Where it started in 2009: I like half wave dipoles. They are easy to make and easy to ... To: [email protected] Subject: [qrp-tech] KN5L EFHW Unun. When designing a broadband transformer, there are several parameters. which can be adjusted for an optimized frequency response: Increased coefficient of coupling, decreased leakage inductance, can be. achieved by placing the primary and secondary windings closer together.A few more comments about this 49:1 autotransformer EFHW design. It seems to work best when the transformer is from ~1m to 2m from the ground. A ground rod from the braid side of the feedline at the transformer is a good best practice. My experience is a coax length of 1/4 wavelength of the lowest band is helpful in some setups.Fixed Impedance Ratio Lower Leakage Inductance End-Fed Half-Wave Transformer by Daniel Marks, KW4TI February 28, 2017 This document describes and characterizes a winding pattern for an autotransformer suitable for an end-fed half-wave antenna. These transformers must match loads of 2000-4000 ohms which is a Below is a visual representation of a way that works properly. To get a 35 uH coil around a 19 mm PVC pipe, one can use 80 windings of 0,75 mm (0,44 mm2) winding wire. For the 110 uH coil one can make 170 windings with 0.5 mm (0.20 mm2) winding wire. For deviating coils or a different diameter of winding wire, the following tool exists. Ratio is for 2450 Ohm (1:49 transformer) Tail current is only 15% of peak in wire Not a big stretch to cut off tail wa7ark 24 EFHW as a multi-band antenna EF resonates on all harmonics, Resonance not exact integer multiples Requires Compensation coil, about 6ft from transformer Aligns the SWR dips on harmonics Coil makes it "longer"Once you start winding the core, you will want to leave a couple inches of twisted primary sticking out to connect to the ground terminal and also a couple inches of single wire at the other end of the primary to attach to the SO-239 center. Wind 3 turns primary and 21 turns secondary for a total of 24 turns.Nov 13, 2012 · With EFHW antennas using an adjustable matchbox there is a great willingness to use the tuning of the matchbox to “fix” a detuned wire or a wrong length wire. IF you do that its not an EFHW as its now a random wire with a random wire tuner and one must use a ground or counterpoise to work against. Oct 03, 2014 · 3. Any transformer connected to 240V AC has to have sufficient inductance in the primary so that it isn't taking a large magnetization current - just think of the primary and ignore the secondary for now - imagine you are only making an inductor to connect to the AC - you don't want it taking ten amps just by itself. K6ARK specifies 3 primary and 21 secondary windings. This means 21/3=7 and 7x7=49, so he's got you winding a 49:1 transformer. Using 2420 ohms (2 half watt resistors, one 2.2k and one 220 ohm) with my big 49:1 transformer, I get acceptable SWR under 3:1 on 29 meters, and under 1.5:1 on 80 meters. Resistance shows 36.something ohms on 20 meters. Step 1: Wrap the green wire around the toroid seven times, feeding the first wind under the toroid. Step 2: Wrap the yellow wire around the toroid seven times, feeding the first wind under the toroid. Step 3: Wrap the blue wire around the toroid three times, feeding the first wind under the toroid.2. Using the EFHW for 20m at GB0CMS 3. EFHW featured in "Stealth Antennas" 3. More about earthing/ground radials 4. Using the 20m EFHW on 10m 5. Detailed construction notes 6. Turning the EFHW into a four-band antenna 7. The 20m-17m-15m three-band trapped EFHW Where it started in 2009: I like half wave dipoles. They are easy to make and easy to ... Step 1: Wrap the green wire around the toroid seven times, feeding the first wind under the toroid. Step 2: Wrap the yellow wire around the toroid seven times, feeding the first wind under the toroid. Step 3: Wrap the blue wire around the toroid three times, feeding the first wind under the toroid.May 27, 2020 · The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1 Nov 14, 2020 · A 1:49 matching transformer is used to match the output of the transmitter and feedline to the antenna. These are conventionally made by winding transformers on a ferrite core with a 1:7 turns ratio. In my small garden even with an inverted configuration as shown the lowest frequency I can fit half a wavelength in is 7MHz for the 40 meter ... Below is a visual representation of a way that works properly. To get a 35 uH coil around a 19 mm PVC pipe, one can use 80 windings of 0,75 mm (0,44 mm2) winding wire. For the 110 uH coil one can make 170 windings with 0.5 mm (0.20 mm2) winding wire. For deviating coils or a different diameter of winding wire, the following tool exists. End-fed, half-wave antennas (EFHWs) are a half-wavelength long and are resonant antennas on the band of interest. They use some kind of matching network to trasnsform the very high impedance at the end of a half-wave wire to about 50 Ω. Generally, they are not usable on bands for which they are not a half wavelength long.10) Winding the 49:1 Transformer Core 2)Wrap the single part of the wire around the core 12 times. Use about ¾ of the core. You may, optionally, choose to make turn 7 a crossover turn to the other side of the balun; this is not done for any magnetic or RF reasons, but to make the wire emerge from the top center of the core for wiring convenience.Jun 06, 2020 · The primary winding capacitor is not needed for EFHW antennas that operate as a single half wave for 20 meters and below. For 15 meters and above a capacitor should be considered, insertion loss is decreased for transformers with a primary winding capacitor. End Feed Half Wave (EFHW) Portable antenna FT140x1. Built using a single Fair-Rite T140-43 core with 49:1 winding and 2kv 100PF capacitor. The antenna comes with a BNC connector, screw top post for the antenna wire and 10.25m of lightweight antenna wire. ... The total weight of the transformer, winder with 10.25m antenna wire is approx. 135gm ...2. Using the EFHW for 20m at GB0CMS 3. EFHW featured in "Stealth Antennas" 3. More about earthing/ground radials 4. Using the 20m EFHW on 10m 5. Detailed construction notes 6. Turning the EFHW into a four-band antenna 7. The 20m-17m-15m three-band trapped EFHW Where it started in 2009: I like half wave dipoles. They are easy to make and easy to ... Since may of all of these EFHW antennas use the coax as a counterpoise, what is the ... I found one that instead of a fully isolated transformer, it used an auto transformer design so, at least in my mind, there was a complete circuit. ... So I started taking winding off and the whole thing started to behave. I got down to 10 turns total and no ...K6ARK specifies 3 primary and 21 secondary windings. This means 21/3=7 and 7x7=49, so he's got you winding a 49:1 transformer. Using 2420 ohms (2 half watt resistors, one 2.2k and one 220 ohm) with my big 49:1 transformer, I get acceptable SWR under 3:1 on 29 meters, and under 1.5:1 on 80 meters. Resistance shows 36.something ohms on 20 meters. Built using a single Fair-Rite T140-43 core with 49:1 winding and 2kv 100PF capacitor. The antenna comes with a BNC connector, screw top post for the antenna wire and 10.25m of lightweight antenna wire. The total weight of the transformer, winder with 10.25m antenna wire is approx. 135gm +-. Ratio is for 2450 Ohm (1:49 transformer) Tail current is only 15% of peak in wire Not a big stretch to cut off tail wa7ark 24 EFHW as a multi-band antenna EF resonates on all harmonics, Resonance not exact integer multiples Requires Compensation coil, about 6ft from transformer Aligns the SWR dips on harmonics Coil makes it "longer"40-20-10m Endfed Antenna. 40-20-10m EndFed Multiband antenna. Such an antenna was always my most want to have item for portable operations and SOTA. I always drooled around the hyEndfed antennas but would never pay over 100 EUR for such an antenna. In the end, it's just a transformer and some wire.the EFHW is transformed down to around 50 Ohms and provides a better match to your coax. Right: Twisting the wire for the bifilar turns on the toroid When winding the toroid it is as well to wrap white PTFE tape around the core to stop arcing. This is plumbers' tape and is very cheap on Ebay. If using an FT240-43, start byUsing a 49:1 transformer shoot for the best 50 Ω match @ appx 2450 Ω load over your working frequency bands. Moving the pot up and down gives a feel for the SWR versus antenna impedance sensitivity. Then verify it with your installed antenna and SWR measurements. Tweak the antenna length if necessary and then maybe adjust the turns ratio again.This is the transformer in a waterproof box: EFHW transformer. The measurements with a 5 kohm resistor (yes I know it's a little to high impedance) gave the following result with my antenna analyzer: ... Your transformer is a 2:16 winding ratio, and a 1:64 transformer, not an unun…perhaps take the 14. winding to the antenna, and achieve a 1 ...Jul 26, 2019 · Your transformer is a 2:16 winding ratio, and a 1:64 transformer, not an unun…perhaps take the 14. winding to the antenna, and achieve a 1:49 transformation to improve swr…..then add a 100pf 15KV capacitor across the feed….yours seems a little lower voltage, and may not last? Best 73 Henrik Being end fed, it needs a transformer to transform the higher impedance of the wire to the 50ish ohms the radio is expecting. There are many resources online that explain the details better than I can, so I'd suggest doing your own research if you'd like to build one for yourself. You can start with the links below. http://www.aa5tb.com/efha.htmlDec 27, 2021 · An end fed half wave antenna, or efhw, is a variation of a half wave dipole, but it is fed from one end. Being end fed, it needs a transformer to transform the higher impedance of the wire to the 50ish ohms the radio is expecting. There are many resources online that explain the details better than I can, so I’d suggest doing your own ... The SWR is high (over 3:1 ) and a reflection of 25% or more will dissipate on the transformer core which can lead to the destruction of the same. If you prefer a 3.8-4MHz sideband (SSB) operation, get an EFHW-7510-2K+ model which has low SWR on 75M and maintains the low SWR on other bands just like the EFHW-8010 model does. BUILD INSTRUCTIONS FOR 49:1 UNUN IMPEDEDENCE TRANSFORMER: 1. PREPARING THE TOROIDS AND WIRE Superglue 2 toroids together. Wait a few minutes for glue to set. Wrap toroids with glass electrical tape. Twist the short and long wires together starting at an end of each wire. Continue twisting the entire length of the short wire.Lets apply the method laid out at PD7MAA's BN43-202 matching transformer for an EFHW. The best Fair-rite data I can find quickly is a chart of the impedance of a one turn winding. Scaling from this graph, Xs is close of 35Ω at 7MHz, so lets used that to derive some basic parameters for the core. Firstly, lets find the permeability of #61 at 7MHz.The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. Winding. Jordan Transformer can remanufacture and upgrade your existing transformer with new copper windings and a custom-made high-density pressboard insulation package. The short circuit design is upgraded to the latest standards. Your new coils are hand-wound in a climate controlled clean room by our team of expert winders. The coupler is a tuned impedance transformer, not an antenna ‘tuning’ unit. Stick to the above, and it should be a sure thing! Feeding a 21MHz half wave. A half wave vertical for 21MHz. 6.65 metres of wire on a 9 metre fibreglass pole. The coupler is mounted 2 metres up and attached to the top of the fence. have never seen before. A small and efficient broadband transformer is used to match the impedance of this EFHW antenna to a 50Ω coaxial cable. The document starts with the definition of the described EFHW antenna system, the author's personal portable antenna requirements, the history of choosing and developingThe coupler is a tuned impedance transformer, not an antenna ‘tuning’ unit. Stick to the above, and it should be a sure thing! Feeding a 21MHz half wave. A half wave vertical for 21MHz. 6.65 metres of wire on a 9 metre fibreglass pole. The coupler is mounted 2 metres up and attached to the top of the fence. End Feed Half Wave (EFHW) Portable antenna FT140x1. Built using a single Fair-Rite T140-43 core with 49:1 winding and 2kv 100PF capacitor. The antenna comes with a BNC connector, screw top post for the antenna wire and 10.25m of lightweight antenna wire. ... The total weight of the transformer, winder with 10.25m antenna wire is approx. 135gm ...EFHW Transformer –alternative designs •The 14T secondary winding can use #18 wire since its current is low. A separate primary winding of 2T #14 wire near the center of the 14T coil will handle the higher current, 5.5 amp at 1500W •See CQ Magazine December 2021: A Deep Dive Into End Fed Half Wave Antennas by Bob Glorioso, W1IS, and Bob Rose, K6ARK specifies 3 primary and 21 secondary windings. This means 21/3=7 and 7x7=49, so he's got you winding a 49:1 transformer. Using 2420 ohms (2 half watt resistors, one 2.2k and one 220 ohm) with my big 49:1 transformer, I get acceptable SWR under 3:1 on 29 meters, and under 1.5:1 on 80 meters. Resistance shows 36.something ohms on 20 meters. A few more comments about this 49:1 autotransformer EFHW design. It seems to work best when the transformer is from ~1m to 2m from the ground. A ground rod from the braid side of the feedline at the transformer is a good best practice. My experience is a coax length of 1/4 wavelength of the lowest band is helpful in some setups.Nov 14, 2020 · A 1:49 matching transformer is used to match the output of the transmitter and feedline to the antenna. These are conventionally made by winding transformers on a ferrite core with a 1:7 turns ratio. In my small garden even with an inverted configuration as shown the lowest frequency I can fit half a wavelength in is 7MHz for the 40 meter ... Feb 12, 2019 · EFHW transformer two ways. Let’s review key differences between the HF and VHF+ transformer configurations. Figure 2 – Difference between transformer configurations. Highlights in figure 2 include: E1 and E2 are both aerials with a length such that a current loop (Hi Z) connects to the top of the each transformer. A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Electromagnetic induction produces an electromotive force within a conductor which is exposed to time varying magnetic fields. Transformers are used to increase or decrease the alternating voltages in electric power applications. 26 libraries of the Electrical ... Fixed Impedance Ratio Lower Leakage Inductance End-Fed Half-Wave Transformer by Daniel Marks, KW4TI February 28, 2017 This document describes and characterizes a winding pattern for an autotransformer suitable for an end-fed half-wave antenna. These transformers must match loads of 2000-4000 ohms which is a This is the transformer in a waterproof box: EFHW transformer. The measurements with a 5 kohm resistor (yes I know it's a little to high impedance) gave the following result with my antenna analyzer: ... Your transformer is a 2:16 winding ratio, and a 1:64 transformer, not an unun…perhaps take the 14. winding to the antenna, and achieve a 1 ...Fixed Impedance Ratio Lower Leakage Inductance End-Fed Half-Wave Transformer by Daniel Marks, KW4TI February 28, 2017 This document describes and characterizes a winding pattern for an autotransformer suitable for an end-fed half-wave antenna. These transformers must match loads of 2000-4000 ohms which is a 9) Winding the 1:1 Choke Balun Core 1)Cut 80" of wire and fold it in half. 2)Tape the wires together with small pieces of electrical tape, with one piece about every 18". Keep the wires flat, like twin lead; do not twist. 3)Using the type 31 ferrite core (with the blue label), wind your balun. Start by allowing aboutRatio is for 2450 Ohm (1:49 transformer) Tail current is only 15% of peak in wire Not a big stretch to cut off tail wa7ark 24 EFHW as a multi-band antenna EF resonates on all harmonics, Resonance not exact integer multiples Requires Compensation coil, about 6ft from transformer Aligns the SWR dips on harmonics Coil makes it "longer"EFHW TOROIDAL TRANSFORMER WINDING 12 •Use a 16:2 turns ratio (8:1) •Impedance ratio is 64:1 •Best to twist wires together going to ground (the 2 turn section) for lower noise •The 2-wire section is a bifilar winding •Wrap the toroid in PTFE (plumber's) tape to prevent arcing if using bare or enameled copper9) Winding the 1:1 Choke Balun Core 1)Cut 80" of wire and fold it in half. 2)Tape the wires together with small pieces of electrical tape, with one piece about every 18". Keep the wires flat, like twin lead; do not twist. 3)Using the type 31 ferrite core (with the blue label), wind your balun. Start by allowing aboutaround the toroid. These magnetic flux lines pass through the secondary winding, and induce a voltage into each turn of the secondary winding. Each additional secondary winding adds an additional voltage so that many secondary windings multiply the voltage, just as each loop of rope around the pulleys multiplies the force lifting the load. Using a 49:1 transformer shoot for the best 50 Ω match @ appx 2450 Ω load over your working frequency bands. Moving the pot up and down gives a feel for the SWR versus antenna impedance sensitivity. Then verify it with your installed antenna and SWR measurements. Tweak the antenna length if necessary and then maybe adjust the turns ratio again.The transformer consists of 2 primary windings and from 14 secondary windings. This gives a ratio of 1 to 7. The voltage is therefore seven times higher than the source voltage and the current is seven times lower than the source current. This results in an impedance transformation of 7 x 7 = 49. That increases the impedance of 50 Ohm by a ...Coax is 50 ohms EFHW is 2500 ohms,,,Humm 49:1 unun is almost 50:1 transformer 2500ohms/50ohm transformed to 50 ohms. That is not all, once the transformation is done at the primary frequency it also transforms the miss match as one varies the frequency of the rig. This decreases the mismatch with varying frequency by 50 times. 9) Winding the 1:1 Choke Balun Core 1)Cut 80" of wire and fold it in half. 2)Tape the wires together with small pieces of electrical tape, with one piece about every 18". Keep the wires flat, like twin lead; do not twist. 3)Using the type 31 ferrite core (with the blue label), wind your balun. Start by allowing aboutWinding a transformer for End Fed Half Wave Antenna; End Fed Half Wave Antenna - 11 Bands One Antenna; And finally this little bit of information: EFHW have better efficiency, lower SWR and is more forgiving on bands covered. EFLW tunes most bands but is 15% less efficient. You can look up more at this link on random wire. Where might you use ...Just another EFHW balun. All commercial EFHW antennas sold are nothing but random chunks of wire and some form of balun. It's incredible that some manufacturer's are charging $250 for these very compromised antennas. You can make your own for about $15, or better yet put up a proper 1/2 wave dipole. 5.K6ARK specifies 3 primary and 21 secondary windings. This means 21/3=7 and 7x7=49, so he's got you winding a 49:1 transformer. Using 2420 ohms (2 half watt resistors, one 2.2k and one 220 ohm) with my big 49:1 transformer, I get acceptable SWR under 3:1 on 29 meters, and under 1.5:1 on 80 meters. Resistance shows 36.something ohms on 20 meters.Winding the matching toroid Using the enamelled copper wire wind 13 turns on the toroid. Each time the wire passes through the toroid counts as one turn. This is the secondary winding. Don't overlap the turns, but keep them quite close together - we may need to space the windings out later when we get to the tuning phase.Feeding the EFHW wire with a 1:50 – 1:60 impedance transformer (unun) instead of an EFHW tuner incorporating a capacitor makes it far less sensitive to the environment stopping the SWR from varying wildly. 2. Adding super lightweight Pico Traps from SOTABeams gives multiband performance without the need for a tuner and without the need to ... See full list on squashpractice.com The hole in the center is too small to fit over a 1/4 inch rod. The IF transformer will be made by sliding the bobbins over 1/4 inch plastic rod. These will not fit the coil winder or the finished transformer. I experimented with drilling out the center hole and enlarging the small holes on the sides to 1/8 inch. This is the transformer in a waterproof box: EFHW transformer. The measurements with a 5 kohm resistor (yes I know it's a little to high impedance) gave the following result with my antenna analyzer: ... Your transformer is a 2:16 winding ratio, and a 1:64 transformer, not an unun…perhaps take the 14. winding to the antenna, and achieve a 1 ...May 27, 2020 · The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1 Feb 24, 2012 · Windings are the conductors wrapped in various forms like helical, disc, cylindrical, crossover which generates MMF that is carried by the core to other windings for having the different levels of voltages. Mainly there are two types of transformer: In core type, we wrap the primary, and secondary windings on the outside limbs, and in shell ... The EFHW transformer box from outside. One cable is the coax feedline, the second is the supply to the cooling fan and control of relays. The 1:64 transformer is wound on 3 stacked FT240-52 toroids, this provides same. inductance as one FT240-43 and is able to withstand 1kW 50/50% duty cycle with help of a cooling fan...Feb 04, 2019 · The transformer configuration produces an inductive component at the 3rd tap wire. A reactance, Xs, is in series between the source and the primary winding to provide the means to compensate for this. This is a core-less air transformer (or “air core” if you like) just in case that isn’t obvious. That series reactance is most often a ... Ratio is for 2450 Ohm (1:49 transformer) Tail current is only 15% of peak in wire Not a big stretch to cut off tail wa7ark 24 EFHW as a multi-band antenna EF resonates on all harmonics, Resonance not exact integer multiples Requires Compensation coil, about 6ft from transformer Aligns the SWR dips on harmonics Coil makes it "longer"BUILD INSTRUCTIONS FOR 49:1 UNUN IMPEDEDENCE TRANSFORMER: 1. PREPARING THE TOROIDS AND WIRE Superglue 2 toroids together. Wait a few minutes for glue to set. Wrap toroids with glass electrical tape. Twist the short and long wires together starting at an end of each wire. Continue twisting the entire length of the short wire.have never seen before. A small and efficient broadband transformer is used to match the impedance of this EFHW antenna to a 50Ω coaxial cable. The document starts with the definition of the described EFHW antenna system, the author’s personal portable antenna requirements, the history of choosing and developing Feb 12, 2019 · EFHW transformer two ways. Let’s review key differences between the HF and VHF+ transformer configurations. Figure 2 – Difference between transformer configurations. Highlights in figure 2 include: E1 and E2 are both aerials with a length such that a current loop (Hi Z) connects to the top of the each transformer. 1) More primary turns and primary inductance improve the transformer efficiency and low end performance. 2) Winding capacitance and leakage inductance, especially present as you increase the number of turns, limit the high frequency performance. 3) Total losses are approximately independent of core volume.Jan 26, 2012 · 18 kV to 13.8 kV, 4.16 kV sounds like a power plant auxiliary transformer fed from the 18 kV generator bus to supply in-plant generator loads. The three winding transformer saves money and space with only one foundation, one HV input, one HV circuit breaker or tap. Disadvantages: Since it is custom, it is hard to find a replacement if it fails. The End-Fed Half-Wave (EFHW) antenna often uses a transformer with a transformation ratio of 49:1 (a turns ratio of 7). A tapped output winding allows the ratio to be selected as well. The schematic and photo below show a typical multi-purpose unun transformer.9) Winding the 1:1 Choke Balun Core 1)Cut 80" of wire and fold it in half. 2)Tape the wires together with small pieces of electrical tape, with one piece about every 18". Keep the wires flat, like twin lead; do not twist. 3)Using the type 31 ferrite core (with the blue label), wind your balun. Start by allowing about2. Using the EFHW for 20m at GB0CMS 3. EFHW featured in "Stealth Antennas" 3. More about earthing/ground radials 4. Using the 20m EFHW on 10m 5. Detailed construction notes 6. Turning the EFHW into a four-band antenna 7. The 20m-17m-15m three-band trapped EFHW Where it started in 2009: I like half wave dipoles. They are easy to make and easy to ... Jul 27, 2021 · July 27, 2021 e73m. Ever since March 2015 when we started to market the High Ratio/Wideband transformers for EFHW antennas the work on R&D (Research & Development) never stopped. The number of limitations in the design of a 49-81:1 ratio of impedance transformation over a large HF frequency spectrum (1-30MHz) was challenging and final designs ... Winding the matching toroid Using the enamelled copper wire wind 13 turns on the toroid. Each time the wire passes through the toroid counts as one turn. This is the secondary winding. Don't overlap the turns, but keep them quite close together - we may need to space the windings out later when we get to the tuning phase.Jul 17, 2020 · For core-type transformers, the windings encircle the core, while in shell-type transformers, the core encircles the windings. Figure 1. Core-type and shell-type transformers work well in high-power applications. There are four ways to connect the primary and secondary windings of the transformers symmetrically. Although this does work as stated I have found that twisting the primary winding does slightly better on the high bands. It's your choice.Please see the late... The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. The transformer configuration produces an inductive component at the 3rd tap wire. A reactance, Xs, is in series between the source and the primary winding to provide the means to compensate for this. This is a core-less air transformer (or "air core" if you like) just in case that isn't obvious. That series reactance is most often a ...have never seen before. A small and efficient broadband transformer is used to match the impedance of this EFHW antenna to a 50Ω coaxial cable. The document starts with the definition of the described EFHW antenna system, the author’s personal portable antenna requirements, the history of choosing and developing around the toroid. These magnetic flux lines pass through the secondary winding, and induce a voltage into each turn of the secondary winding. Each additional secondary winding adds an additional voltage so that many secondary windings multiply the voltage, just as each loop of rope around the pulleys multiplies the force lifting the load. 1) More primary turns and primary inductance improve the transformer efficiency and low end performance. 2) Winding capacitance and leakage inductance, especially present as you increase the number of turns, limit the high frequency performance. 3) Total losses are approximately independent of core volume. For the transformer, you need: ~8 feet - 12 AWG enameled wire 3 - 52-mix torrids for three torrids. 43-mix for 1 or 2 torrids. 1 - 100 PF 5+kv capacitor Cut 2 wires. The primary is about 13". The secondary is about 80" long. Twist the primary with the secondary. The primary should be 2 winds.K6ARK specifies 3 primary and 21 secondary windings. This means 21/3=7 and 7x7=49, so he's got you winding a 49:1 transformer. Using 2420 ohms (2 half watt resistors, one 2.2k and one 220 ohm) with my big 49:1 transformer, I get acceptable SWR under 3:1 on 29 meters, and under 1.5:1 on 80 meters. Resistance shows 36.something ohms on 20 meters.2 turns primary and 14 turns secondary. The crossover counts as a turn. Generally if the SWR is too high on the higher bands, remove a turn and if too high o... Jan 26, 2012 · 18 kV to 13.8 kV, 4.16 kV sounds like a power plant auxiliary transformer fed from the 18 kV generator bus to supply in-plant generator loads. The three winding transformer saves money and space with only one foundation, one HV input, one HV circuit breaker or tap. Disadvantages: Since it is custom, it is hard to find a replacement if it fails. A bifilar-wound coil is one that contains two closely spaced, parallel windings. This can be achieved by winding coils using two insulated conductors. Some bifilar-wound coils have adjacent coils in which the turns are arranged so that the potential difference is magnified (that is, the current flows in the same parallel direction).The SWR is high (over 3:1 ) and a reflection of 25% or more will dissipate on the transformer core which can lead to the destruction of the same. If you prefer a 3.8-4MHz sideband (SSB) operation, get an EFHW-7510-2K+ model which has low SWR on 75M and maintains the low SWR on other bands just like the EFHW-8010 model does. Fixed Impedance Ratio Lower Leakage Inductance End-Fed Half-Wave Transformer by Daniel Marks, KW4TI February 28, 2017 This document describes and characterizes a winding pattern for an autotransformer suitable for an end-fed half-wave antenna. These transformers must match loads of 2000-4000 ohms which is a The color tree multiband EFHW antenna is suitable and reliable and fits well with your daily use. And, this is designed to be used without the use of a tuner, and after optimizing the driven element, swr. The single-band 80m-10m end-feed half-wave linear antenna provides the. The color tree multiband EFHW antenna is suitable and reliable and ...Nov 08, 2021 · The same coil 78" from the transformer would be used on the 133ft version. The MyAntennas 133ft versions I have cover 80 (actually 75m), 40, 30, 20, 17, 15, 12 and 10m all without a tuner. A few of the bands like 30 and 17m are starting to get up around 2:1 VSWR but I just connect my 1200w amp with out any tuner and it just works on all bands. See full list on squashpractice.com Feb 24, 2012 · Windings are the conductors wrapped in various forms like helical, disc, cylindrical, crossover which generates MMF that is carried by the core to other windings for having the different levels of voltages. Mainly there are two types of transformer: In core type, we wrap the primary, and secondary windings on the outside limbs, and in shell ... Sep 24, 2020 · USA. www.dtbradio.com. Sep 24, 2020. #1. I've been puttering around with end-fed half-wave antennas for 40 through 10 meters (concentrating on 40 for now), and have had trouble coming up with a good match-box design. I've tried different ideas from an array of online sources ranging from auto-transformers in various turns ratios to basic L ... Jul 17, 2020 · For core-type transformers, the windings encircle the core, while in shell-type transformers, the core encircles the windings. Figure 1. Core-type and shell-type transformers work well in high-power applications. There are four ways to connect the primary and secondary windings of the transformers symmetrically. Since may of all of these EFHW antennas use the coax as a counterpoise, what is the ... I found one that instead of a fully isolated transformer, it used an auto transformer design so, at least in my mind, there was a complete circuit. ... So I started taking winding off and the whole thing started to behave. I got down to 10 turns total and no ...The antenna system consists of a 40-10 EFHW (~60' Wire matched to a QRPGuys EFHW transformer mounted on a DIY wire winder cut from a yard sign), 5 aluminum tent pegs, 2 pieces of shock or bungee cord for tying off the antenna ends, a 25' BNC terminated RG-174 coax, and a 14-1/2 ft fiberglass fishing pole with DIY collar and guy lines.Jul 27, 2021 · July 27, 2021 e73m. Ever since March 2015 when we started to market the High Ratio/Wideband transformers for EFHW antennas the work on R&D (Research & Development) never stopped. The number of limitations in the design of a 49-81:1 ratio of impedance transformation over a large HF frequency spectrum (1-30MHz) was challenging and final designs ... The primary winding capacitor is not needed for EFHW antennas that operate as a single half wave for 20 meters and below. For 15 meters and above a capacitor should be considered, insertion loss is decreased for transformers with a primary winding capacitor.The secondary winding is then wound on top of the primary winding. After the secondary winding is complete, it too is covered with insulating paper. Next, the E and I sections of the iron core are inserted into and around the windings as shown. The leads from the windings are normally brought out through a hole in the enclosure of the ... Oct 03, 2014 · 3. Any transformer connected to 240V AC has to have sufficient inductance in the primary so that it isn't taking a large magnetization current - just think of the primary and ignore the secondary for now - imagine you are only making an inductor to connect to the AC - you don't want it taking ten amps just by itself. The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. Then wrap the other 12 windings as shown in 5A and 5B, crossing the wire over to the other side of the toroid after the sixth wind. 5A. 5B. Step 7. Cut the loop of the double winding wire end. This creates two loose wires. With a sharp knife or sandpaper, remove the insulation from the winding wire close to the core. The transformer consists of 2 primary windings and from 14 secondary windings. This gives a ratio of 1 to 7. The voltage is therefore seven times higher than the source voltage and the current is seven times lower than the source current. This results in an impedance transformation of 7 x 7 = 49. That increases the impedance of 50 Ohm by a ...Just another EFHW balun. All commercial EFHW antennas sold are nothing but random chunks of wire and some form of balun. It's incredible that some manufacturer's are charging $250 for these very compromised antennas. You can make your own for about $15, or better yet put up a proper 1/2 wave dipole. 5.One way to make the Fuchs antenna multi-band, is to add selectable taps on the primary and/or the secondary side of the transformer. Further "tuning" can be done with a variable capacitor across the selected tap of the antenna-side winding of the transformer and the "bottom" of that winding. Ref. 1.Oct 20, 2018 · According to some sources (ref.1), an end-fed half-wave antenna needs a 0.05 lambda counterpoise to work correctly. In the case of the "EndFedz" EF-10/20/40 and its clones, where we are effectively using the coax as a counterpoise, we can meet this requirement by ensuring the feeder is at least 0.05 wavelengths long at the lowest operating ... The transformer consists of 2 primary windings and from 14 secondary windings. This gives a ratio of 1 to 7. The voltage is therefore seven times higher than the source voltage and the current is seven times lower than the source current. This results in an impedance transformation of 7 x 7 = 49. That increases the impedance of 50 Ohm by a ...K6ARK specifies 3 primary and 21 secondary windings. This means 21/3=7 and 7x7=49, so he's got you winding a 49:1 transformer. Using 2420 ohms (2 half watt resistors, one 2.2k and one 220 ohm) with my big 49:1 transformer, I get acceptable SWR under 3:1 on 29 meters, and under 1.5:1 on 80 meters. Resistance shows 36.something ohms on 20 meters.More coax is good in this case because its more antenna to radiate. If you want an end fed for 160m that actually works well you would go with a full 1/2 wavelength of wire (about 250ft) fed with a transformer that has a very high impedance output to match the 1/2 wave end fed. Several companies make the transformer and complete antennas and if ...EFHW transformer two ways. Let's review key differences between the HF and VHF+ transformer configurations. Figure 2 - Difference between transformer configurations. Highlights in figure 2 include: E1 and E2 are both aerials with a length such that a current loop (Hi Z) connects to the top of the each transformer.A few more comments about this 49:1 autotransformer EFHW design. It seems to work best when the transformer is from ~1m to 2m from the ground. A ground rod from the braid side of the feedline at the transformer is a good best practice. My experience is a coax length of 1/4 wavelength of the lowest band is helpful in some setups.the EFHW is transformed down to around 50 Ohms and provides a better match to your coax. Right: Twisting the wire for the bifilar turns on the toroid When winding the toroid it is as well to wrap white PTFE tape around the core to stop arcing. This is plumbers' tape and is very cheap on Ebay. If using an FT240-43, start byBelow is a visual representation of a way that works properly. To get a 35 uH coil around a 19 mm PVC pipe, one can use 80 windings of 0,75 mm (0,44 mm2) winding wire. For the 110 uH coil one can make 170 windings with 0.5 mm (0.20 mm2) winding wire. For deviating coils or a different diameter of winding wire, the following tool exists. The EFHW transformer box from outside. One cable is the coax feedline, the second is the supply to the cooling fan and control of relays. The 1:64 transformer is wound on 3 stacked FT240-52 toroids, this provides same. inductance as one FT240-43 and is able to withstand 1kW 50/50% duty cycle with help of a cooling fan...Lets apply the method laid out at PD7MAA's BN43-202 matching transformer for an EFHW. The best Fair-rite data I can find quickly is a chart of the impedance of a one turn winding. Scaling from this graph, Xs is close of 35Ω at 7MHz, so lets used that to derive some basic parameters for the core. Firstly, lets find the permeability of #61 at 7MHz.The coupler is a tuned impedance transformer, not an antenna ‘tuning’ unit. Stick to the above, and it should be a sure thing! Feeding a 21MHz half wave. A half wave vertical for 21MHz. 6.65 metres of wire on a 9 metre fibreglass pole. The coupler is mounted 2 metres up and attached to the top of the fence. around the toroid. These magnetic flux lines pass through the secondary winding, and induce a voltage into each turn of the secondary winding. Each additional secondary winding adds an additional voltage so that many secondary windings multiply the voltage, just as each loop of rope around the pulleys multiplies the force lifting the load. Feeding the EFHW wire with a 1:50 – 1:60 impedance transformer (unun) instead of an EFHW tuner incorporating a capacitor makes it far less sensitive to the environment stopping the SWR from varying wildly. 2. Adding super lightweight Pico Traps from SOTABeams gives multiband performance without the need for a tuner and without the need to ... 2 turns primary and 14 turns secondary. The crossover counts as a turn. Generally if the SWR is too high on the higher bands, remove a turn and if too high o... Being end fed, it needs a transformer to transform the higher impedance of the wire to the 50ish ohms the radio is expecting. There are many resources online that explain the details better than I can, so I'd suggest doing your own research if you'd like to build one for yourself. You can start with the links below. http://www.aa5tb.com/efha.htmlJul 27, 2021 · July 27, 2021 e73m. Ever since March 2015 when we started to market the High Ratio/Wideband transformers for EFHW antennas the work on R&D (Research & Development) never stopped. The number of limitations in the design of a 49-81:1 ratio of impedance transformation over a large HF frequency spectrum (1-30MHz) was challenging and final designs ... Issues with high SWR on HF Kits EFHW 49:1 UnUn kit. I recently tried assembling a EFHW kit, and some problems came up in testing. I believe this is the kit; I bought it through ARRL: HF Kits website. This is my first time making an UnUn and EFHW kit. For this I have a nanoVNA running 10 segment sweeps on the UnUn with two gator clips on each end.Ratio is for 2450 Ohm (1:49 transformer) Tail current is only 15% of peak in wire Not a big stretch to cut off tail wa7ark 24 EFHW as a multi-band antenna EF resonates on all harmonics, Resonance not exact integer multiples Requires Compensation coil, about 6ft from transformer Aligns the SWR dips on harmonics Coil makes it "longer"In order to evaluate the choking characteristics of the "red" toroids, I prepared two chokes by winding 12 coils of RG-58 on a iron powder T200-2 toroid and a ferrite FT240-43 one. ... They say the 43 material is the stuff to use for ferrite 49:1 or 4:1 for Delta Loop or EFHW balun transformers… it'll work but it's not the best stuff. ...May 27, 2020 · The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1 Nov 08, 2021 · The same coil 78" from the transformer would be used on the 133ft version. The MyAntennas 133ft versions I have cover 80 (actually 75m), 40, 30, 20, 17, 15, 12 and 10m all without a tuner. A few of the bands like 30 and 17m are starting to get up around 2:1 VSWR but I just connect my 1200w amp with out any tuner and it just works on all bands. So you have an EFHW sloper.... perfectly legitimate configuration. GREAT that it works so well on 20 and 40. ... It uses an Amidon FT240-43 Toroid and wound with 1.0mm copper winding wire. ... for that specific kit but MyAntennas places a coil (5 turns of the antenna wire around a 2" dia form) 78" from the transformer. I believe the coil helps ...A shortened multi-band End-Fed Half Wave (EFHW) antenna for 80-10m Steve Nichols G0KYA A shortened multiband antenna, about 23m long, for 80m-10m that offers low SWR (1.3:1) on 80m and 40m, and below 3:1 on 20, 15 and 10m. The antenna has a full 300kHz bandwidth on 80m between 3:1 SWR points. But performance is down about 8-12db on a dipole on 80m.Anyway. On an EFHW, what part in the transformer makes it a single versus multi band? I ask because I've built some that were resonant across multiple bands. 49:1 for instance with a 133' element. But with the QRP EFHW, it's only resonant on the band in which the element is cut for. So is it the toroid? The winding of the toroid? The capacitor?All commercial EFHW antennas sold are nothing but random chunks of wire and some form of balun. It's incredible that some manufacturer's are charging $250 for these very compromised antennas. You can make your own for about $15, or better yet put up a proper 1/2 wave dipole. 5. Unique Models Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Current delivery time 7-10 days. Learn More Shipping: Calculated at Checkout $95.95 Select Configuration: Required Model 49131e - Eyebolt for Antenna Connection Model 49131sw - Stud with Wing Nut for Antenna Connection Next availability TBDUsing a 49:1 transformer shoot for the best 50 Ω match @ appx 2450 Ω load over your working frequency bands. Moving the pot up and down gives a feel for the SWR versus antenna impedance sensitivity. Then verify it with your installed antenna and SWR measurements. Tweak the antenna length if necessary and then maybe adjust the turns ratio again.One way to make the Fuchs antenna multi-band, is to add selectable taps on the primary and/or the secondary side of the transformer. Further "tuning" can be done with a variable capacitor across the selected tap of the antenna-side winding of the transformer and the "bottom" of that winding. Ref. 1.Then wrap the other 12 windings as shown in 5A and 5B, crossing the wire over to the other side of the toroid after the sixth wind. 5A. 5B. Step 7. Cut the loop of the double winding wire end. This creates two loose wires. With a sharp knife or sandpaper, remove the insulation from the winding wire close to the core. EFHW transformer two ways. Let's review key differences between the HF and VHF+ transformer configurations. Figure 2 - Difference between transformer configurations. Highlights in figure 2 include: E1 and E2 are both aerials with a length such that a current loop (Hi Z) connects to the top of the each transformer.Feb 12, 2019 · EFHW transformer two ways. Let’s review key differences between the HF and VHF+ transformer configurations. Figure 2 – Difference between transformer configurations. Highlights in figure 2 include: E1 and E2 are both aerials with a length such that a current loop (Hi Z) connects to the top of the each transformer. NanoVNA measurement of an EFHW Transformer Ariel NY4G #21334 . Is there someone in this group that has measured the loss associated with a transformer of this type and can steer me either to a thread or a discussion on how this was done? Much appreciated response Ariel NY4G. More. All Messages By This Member; Gary W9TD ...The coupler is a tuned impedance transformer, not an antenna ‘tuning’ unit. Stick to the above, and it should be a sure thing! Feeding a 21MHz half wave. A half wave vertical for 21MHz. 6.65 metres of wire on a 9 metre fibreglass pole. The coupler is mounted 2 metres up and attached to the top of the fence. May 27, 2020 · The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1 Mar 15, 2020 · ICOM IC-V3500 – 144 MHz FM – 65 W. July 14, 2022 No comments. ICOM IC-V3500 65 W Powerful RF Output Power The Icom IC-V3500 is a rugged 2 m mobile transceiver providing powerful 65 W* of output power. A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Electromagnetic induction produces an electromotive force within a conductor which is exposed to time varying magnetic fields. Transformers are used to increase or decrease the alternating voltages in electric power applications. 26 libraries of the Electrical ... To: qrp-tech[email protected] Subject: [qrp-tech] KN5L EFHW Unun. When designing a broadband transformer, there are several parameters. which can be adjusted for an optimized frequency response: Increased coefficient of coupling, decreased leakage inductance, can be. achieved by placing the primary and secondary windings closer together.May 13, 2015 · MEF-330-1K Multi Band End Fed Half Wave Antenna Transformer. This is an End-Fed Half Wave antenna (EFHW) Transformer for frequencies between 3 and 30 MHz. To use it at any frequency in this 3-30MHz spectrum just add half wave long wire for the frequency of your interest. Benefit of the EFHW antenna is that it will be resonant on harmonic ... Lets apply the method laid out at PD7MAA's BN43-202 matching transformer for an EFHW. The best Fair-rite data I can find quickly is a chart of the impedance of a one turn winding. Scaling from this graph, Xs is close of 35Ω at 7MHz, so lets used that to derive some basic parameters for the core. Firstly, lets find the permeability of #61 at 7MHz.End Feed Half Wave (EFHW) Portable antenna FT140x1. Built using a single Fair-Rite T140-43 core with 49:1 winding and 2kv 100PF capacitor. The antenna comes with a BNC connector, screw top post for the antenna wire and 10.25m of lightweight antenna wire. ... The total weight of the transformer, winder with 10.25m antenna wire is approx. 135gm ...May 27, 2020 · The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1 Below a picture of the transformer with 2 resistors connected acting like a load for SWR control with a VNA. More details about construction can be found on PA3HHO Web page [4] and in the Facebook group [3] The coupler is the original EFHW adapter solution and is build to allow a tuning on any frequency with a bit more "fine tuning".Feb 04, 2019 · The transformer configuration produces an inductive component at the 3rd tap wire. A reactance, Xs, is in series between the source and the primary winding to provide the means to compensate for this. This is a core-less air transformer (or “air core” if you like) just in case that isn’t obvious. That series reactance is most often a ... A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Electromagnetic induction produces an electromotive force within a conductor which is exposed to time varying magnetic fields. Transformers are used to increase or decrease the alternating voltages in electric power applications. 26 libraries of the Electrical ... Below a picture of the transformer with 2 resistors connected acting like a load for SWR control with a VNA. More details about construction can be found on PA3HHO Web page [4] and in the Facebook group [3] The coupler is the original EFHW adapter solution and is build to allow a tuning on any frequency with a bit more "fine tuning".Search: Efhw Balun. EFHW-8010-2K Multiband End Fed Half Wave Antenna 130 Feet (39 The NooElec Balun 1:9 v2 Most communications applications deal with two-terminal sources 0 0 1 212 1171 Com One LTD 9 2 1381 14 Dec 7, 2016 - End Fed Antenna EFHW Rhel 7 Change Screen Resolution Command Line Dec 7, 2016 - End Fed Antenna EFHW. I do run a tuner though and requires a 4-1 balun 4 watts (neglecting ...Lets apply the method laid out at PD7MAA's BN43-202 matching transformer for an EFHW. The best Fair-rite data I can find quickly is a chart of the impedance of a one turn winding. Scaling from this graph, Xs is close of 35Ω at 7MHz, so lets used that to derive some basic parameters for the core. Firstly, lets find the permeability of #61 at 7MHz.The antenna system consists of a 40-10 EFHW (~60' Wire matched to a QRPGuys EFHW transformer mounted on a DIY wire winder cut from a yard sign), 5 aluminum tent pegs, 2 pieces of shock or bungee cord for tying off the antenna ends, a 25' BNC terminated RG-174 coax, and a 14-1/2 ft fiberglass fishing pole with DIY collar and guy lines.Search: Efhw Balun. EFHW-8010-2K Multiband End Fed Half Wave Antenna 130 Feet (39 The NooElec Balun 1:9 v2 Most communications applications deal with two-terminal sources 0 0 1 212 1171 Com One LTD 9 2 1381 14 Dec 7, 2016 - End Fed Antenna EFHW Rhel 7 Change Screen Resolution Command Line Dec 7, 2016 - End Fed Antenna EFHW. I do run a tuner though and requires a 4-1 balun 4 watts (neglecting ...The transformer was attached to the 30 meter EFHW antenna and turns were removed for best match to 50 ohms. The final turns ratio turned out to be 3:29. 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. The SWR for the 20 meter EFHW antenna was < 1.2:1. The hole in the center is too small to fit over a 1/4 inch rod. The IF transformer will be made by sliding the bobbins over 1/4 inch plastic rod. These will not fit the coil winder or the finished transformer. I experimented with drilling out the center hole and enlarging the small holes on the sides to 1/8 inch. 2. Using the EFHW for 20m at GB0CMS 3. EFHW featured in "Stealth Antennas" 3. More about earthing/ground radials 4. Using the 20m EFHW on 10m 5. Detailed construction notes 6. Turning the EFHW into a four-band antenna 7. The 20m-17m-15m three-band trapped EFHW Where it started in 2009: I like half wave dipoles. They are easy to make and easy to ... The antenna system consists of a 40-10 EFHW (~60' Wire matched to a QRPGuys EFHW transformer mounted on a DIY wire winder cut from a yard sign), 5 aluminum tent pegs, 2 pieces of shock or bungee cord for tying off the antenna ends, a 25' BNC terminated RG-174 coax, and a 14-1/2 ft fiberglass fishing pole with DIY collar and guy lines. This is a hand made EFHW Antenna with a built in 49:1 Transformer. This is incredible for POTA, SOTA and other portable/field operations. Setup in any end fed configuration you like. Please let me know if you are interested in a different configuration. With wire, without, 20m, 40m, etc.1) More primary turns and primary inductance improve the transformer efficiency and low end performance. 2) Winding capacitance and leakage inductance, especially present as you increase the number of turns, limit the high frequency performance. 3) Total losses are approximately independent of core volume.Unique Models Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Model 49131 - 49:1 - 80-10m EFHW - Up to 1kW Current delivery time 7-10 days. Learn More Shipping: Calculated at Checkout $95.95 Select Configuration: Required Model 49131e - Eyebolt for Antenna Connection Model 49131sw - Stud with Wing Nut for Antenna Connection Next availability TBDMar 15, 2020 · ICOM IC-V3500 – 144 MHz FM – 65 W. July 14, 2022 No comments. ICOM IC-V3500 65 W Powerful RF Output Power The Icom IC-V3500 is a rugged 2 m mobile transceiver providing powerful 65 W* of output power. This is the transformer in a waterproof box: EFHW transformer. The measurements with a 5 kohm resistor (yes I know it's a little to high impedance) gave the following result with my antenna analyzer: ... Your transformer is a 2:16 winding ratio, and a 1:64 transformer, not an unun…perhaps take the 14. winding to the antenna, and achieve a 1 ...Feb 28, 2021 · Our Low band transformers for 1.8-8Mhz such as MEF-105-5K, MEF-107-4K, and MEF-107-2K-Plus feature insertion losses of only 0.07-0.25dB. For increased power handling on digital modes such as FT8, we developed also a MEF-330-2K-Plus transformer for 3-30MHz with an average loss of only 0.47dB. See some of our Insertion loss charts and explanation ... xa