How to test a 9 1 unun It is placed at the connection of the coax coming from the radio (50 ohm) and connected to the end of the ladder line (450 ohm) as 9 x 50 = 450. Aug 18, 2022 · DIY Homebrew Linked End-Fed Half Wave (EFHW) Antenna With 64:1 Impedance Transformer (Unun) for 17M, 15M, 12M, and 10M Mar 16, 2020 · Checking 1:49 UnUn with nanovna#applications Apr 12, 2025 · Simple bench test for the impedance transformation of 49:1 Unun used for End Fed Half Wave (EFHW) dipole antennas which are quite popular for ham radio Jul 16, 2011 · I next decided to investigate how UnUns of different designs compared. This video will show you how to set up a NanoVNA for testing baluns, chokes, filters, antenna switches and more. Here I show you how you can check if you 49:1 unun is working using a NanoVNA and some resistors. If you do, dont be surprised if it doesn't work well (may actually tune up, but so do dummy loads- likely won't transmit efficiently). Feb 7, 2024 · Along my journey on understanding radio, electronics, and in particular, the magic of baluns, ununs, and other transformers, I came across this helpful video on how to analyze a 49:1 unun with a NanoVNA. Most commonly wound with ferrite cores and specific winding ratios (such as 4:1, 9:1, or even 49:1), an unun transforms the impedance of the antenna to something closer to the 50-ohm input of your radio. 5 - 60MHz). 8 - 30MHz). If the input is 100 W into 50 Ω, then since W=V²/R, the input voltage is √ (100*50) = 71 V rms. 5-50mhz). Possibly move the unun “guts” into a smaller/better box. Nicely done! Should have the right design margin for 80m, 3x ft240-52 at 2 turns is 80 ohms at 3. This video shows step by step how to wind a 9:1 unun. The primary to secondary winding ratio is 1 to 7, thereby providing the 50-ohm to 3,200-ohm match. Oct 27, 2022 · An EFHW usually has a 49:1 unun; not a 9:1. amidoncorp. Bottom counterpoise. Consider rebuilding it with a larger gauge magnet wire. This matching is crucial for efficient power transfer and minimizing signal loss. This is what happens when we offer a balun design without understanding or measuring balance. The 64:1 auto-transformer (UNUN) in this article will do just that by matching the 3,200 ohms input of an end-fed wire to the 50-ohm output of the transceiver. Just a quick video showing how you can test your EFHW 49:1 UnUn for Impedance Matching / Transformation. Step 4: Wind the 9:1 unun toroidal transformer. Try making a 64:1 unun (with 24:3 turns) and compare it to this one. 👍 *Support B Don't run away! Sorry for the 15 second delay before the video starts. UNUN 9:1 VOLTAGE VERSION 3 9:1 voltage unun using a FT140-43 ferrite core (0. The gain (loss) reading in negative dB gives us the total signal loss through the windings. It shows resonance around 15. A 4:1 single-core "current balun", as presented in "Baluns and Unun's" and used in some commercial designs, forces a system into gross voltage unbalance. Go to the next step. A 4:1 balun (balanced to unbalanced) or UNUN (unbalanced to Time to make another Transformer/UnUn this time for curiosity and perhaps for my holidays ( if there's room in the car). This p We would like to show you a description here but the site won’t allow us. I was hoping to see a much flatter swr over the HF spectrum with 450ohm resistor connected in place of the antenna (vna is showing 3. You might be able to use a DC meter IF it can measure very low resistances (milliohms) and IF the same wire Hello all! I've created my first 9:1 unun and tested it by using 450ohm resisters across the antenna out and the ground. It looks good to me, but curious if I'm looking at this right. I'm only going to run about 10-15 It's time to see if the unun from Bangood actually ununs (is that a real word?) like it should, and show you how to test your ununs. This video dives into the power loss, insertion loss, and efficiency of the 49:1 UnUn (balun) with a 14/2 winding pattern on FT240-43 toroids. Of course, results will vary depending on the actual load, but with a decent tuner, you'll be able to have fun with this simple impedance transformer with all kinds of random wire antennas. Install per step 3 in 9:1 unun instructions. }} 9:1 Magnetic Longwire Balun / Unun Completed 9:1 UnUn These are sometimes known as a Magnetic Longwire Balun. Because this discussion focuses on the end-fed an-tenna, let’s examine how to build a 9:1 unun for it, then explain the modification necessary for a 9:1 balun for a balanced target such as ladder-line. These two objects require 9:1 imped-ance transformation, but in different ways. Apr 14, 2002 · On 80 meters, the 9:1 unun shows about a 3:1 SWR, on 40 meters, it's right at 2:1 SWR, and it flattens out at 20 meters and stays under 2:1 SWR through most of 10 meters. You will need a T-200 (red) toroid and three pieces of wire, each 24 inches (60cm) long . I tried my bunny-bitten coax and it tested the same after making sure the connections were tight. How to build 49:1 matching transformers. All should have ~0 ohms resistance between them. The most accurate way would be to connect an antenna analyzer across the coax terminals and a 200 ohm resistor across the antenna terminals. Note: For the 20w kit, nest the two toroids concentrically, and then follow these instructions treating the two toroids as if they are one. I don't see where the OP said that the transformer/unun was 9:1 so I am assuming from the description that it is truly an EFHW with a 49:1 unun. Otherwise, most DIY baluns/ununs would likely be 1:1, 4:1, 9:1, 49:1, or 64:1, so you could try terminating the ‘balanced’ side with fixed resistors of approximately 50, 200, 450, 2450, and 3200 ohms to see which yields the flattest SWR trace. How to build the 9:1 UnUn / balun matching transformer to use with a random wire antenna. In this video, we use a RigExpert AA-30. The crossover is nice and a good way to wind Step 5: Wind the ~49:1 unun toroidal transformer. Definitely try 80m. Jul 24, 2022 · Unun Insertion Loss (Efficiency) Testing by Joshua (KO4AWH) A simple “side-by-side’ method can be deployed with the use of a Calibrated NanoVNA to read back “S21 Gain” which is, in this case, signal loss from the output of S11 back into S21 through the identical windings. Subscribe: https:/ Measuring a balun with a DC ohmmeter is tough because of the low resistance of the windings. It’s a good idea to test the matching unit before installing the final heat shrink. For about $17, I’m very happy with it so far. I am testing to confirm the 9:1 is wrapped correctly and there are no issues with the Aug 11, 2025 · With the view to establish a quick and easy multi-band antenna deployment for portable and camping operations a simple long wire antenna with an earth or earth plus counterpoise arrangement with a 9:1 voltage unun is one possible solution. End-fed, half-wave antennas (EFHWs) are a half-wavelength long and are resonant Oct 11, 2024 · Building the 9:1 antenna with common mode choke. By following these steps and using the right materials, you can create a reliable unun that will serve you well in your radio communications. Top counterpoise. 👍 Support BudgetHamRadio channel - https://buymeacoffee. That way your impedances will be correct. Balun = unbalanced coax to balanced antenna Unun = unbalanced coax to unbalanced antenna But if I'm understanding correctly a 9:1 balun and a 9:1 unun differ only in what's connected to them, ya? The types of antennas offer thr shelf 9:1 baluns claim to be good for are the same kind of antennas that online sources say you need an unun for The continuity test is DC, but when you start putting radio-frequency AC through it, the reactance (inductance) of the wound toroid presents itself =] { {Series inductors are low-pass filters. In this video, we dive deep into the topic of optimizing ham radio antennas by exploring the incredible power of 4:1 baluns and UNUNs. Sep 24, 2022 · That should give you a rough idea what impedance matching ratio your balun is wound for. com. 5mhz. Uncoil the magnet wire. Lets build a 9:1 Unun… Well you need to start with a toroid of #61 material and get a plastic box to house it. If it were done with 2 you'd be just barely above 50. 9:1 UNUN Testing : Interesting Discoveries Using a NanoVNA Never throw away your old ceiling fan! Turn your bike into an electric bike with a ceiling fan motor This is part 2 of a 4 part video that discussed how to build and test a multiband long wire antenna, a 9:1 Unun, a 1:1 RF choke, and an antenna tuner. So if you're someone who has that same question this is a video for you. 👍Support This video is about How to home made the Mini 9:1 or Mini 49:1 UNUN transformers (designed by me OM0ET). This is part 1 of a 4 part video that discussed how to build and test a Multiband Long Wire Antenna, a 9:1 Unun, a 1:1 RF choke, and an Antenna Tuner. Jan 28, 2020 · Testing 9:1 UnUn with 470 ohm resistor in output side using nanovna. I've not hooked it up to the wire yet. What you could do first is to put a non-inductive resistor on the far end, for example if that is a 9:1 transformer, then put a 9x50 ohm (450 ohm) resistor on the far end and then test reflection coefficient (S11) from the near end. Before I get into the nitty-gritty details, let me first make a distinction between end-fed half-wave antennas, such as the ones sold by LNR Precision and end-fed wires that use some kind of tuning to achieve a 50 Ω output impedance. The 1:1 balun (common-mode choke) goes between coax and the 9:1, regardless of type. A balun or unun with low SWR over a very wide frequency range might not be a good balun or unun anywhere! As a matter of fact, a balun that isn't even a balun, one that always forces a system into severe common mode problems, can test perfectly on a simple SWR to load or SWR to antenna testing. I was thinking that if I connect a 450 ohm resistor across the antenna and ground terminals I would be able to check the SWR of my unun with my antenna analyser over various bands. An Amidon FT-240- 43 core is used and sells for $8 at Amidon www. As a result, power transfer improves significantly, and tuners work more efficiently. Presumably the ferrite toroid works better for the lower bands, 40 and 80m In this video, we take a look at two UnUn's that my buddy made to use for SWL and QRP operations. This is a brief demonstration on how I test a 9:1 before my deployment. I plan on using this on as a 40-10 EFHW. Check for DC continuity between the counterpoise (if you installed one), the antenna wire, the BNC ground, and the BNC center pin. If you have any questions or need further assistance, feel free to ask! Apr 12, 2025 · To check the efficacy of 49:1 unun or impedance transformer, we need to connect the 50 ohms side to the S11 port of the NanoVNA. Step 7: Test the matching unit. To be Oct 24, 2020 · I suspected my old 50 foot coax was bad or suspect since bunnies had bitten into it in several areas so I tested some newer 1,3,25,50 cables and they all tested identical to my VNA being directly connected to the UnUn. Its really an impedance transformer (9:1) to feed a high impedance, end fed (unbalanced) random wire which is likely to be a few hundred ohms, and transform it into something closer to a 50Ω (unbalanced) coaxial input, hence UnUn. . We can then divide by 2 May 13, 2020 · Using Antscope 2 to check baluns ?1 - 12 of 12 1 Building a 9:1 UNUN for a random-wire multi-band end-fed antenna using an FT-140-43 toroid instead of the usual T106-2. This video is about testing the SWR of the antenna without a tuner in order to find out what we'll be expecting our Tuner to match. Additionally, we go through the process of building a 9:1 Unun for an EFRW Antenna. It is not a balun. Nov 17, 2024 · Building a 9:1 unun is a rewarding project that can enhance your amateur radio setup by ensuring efficient transmission and reception. Other side which involves the antenna terminal and the ground should be connected to a 2500 ohms resistor to simulate the high impedance of the EFHW. I wound a 9:1 UnUn comprising 9 trifilar turns on a T200-2 core, a 4:1 UnUn comprising 12 bifilar turns on a FT240-61 core, and a 4:1 UnUn comprising 12 bifilar turns on a FT240-31 core; here are the results: Clearly, introducing any of the UnUns makes a dramatic improvement to the SWR on most of the bands; the exceptions Aug 11, 2025 · UNUN 9:1 VOLTAGE VERSION 2 9:1 voltage unun using a L15 ferrite core (1. Show step by step how to build several different variations and how to measure and compare their insertion losses and efficiency. In short, I am very impressed with how easy this was to build and how effectively it matches the 450 Ohm impedance found at the end of a proper length random wire Jun 17, 2009 · If you want to build your own follow these instructions: Building a 9:1 unun Note: you could also use a T130-2 toroid, but that will be limited to a maximum of about 75-100W. So I bought it and adventured into my first 9:1 UnUn transformer build. If the analyzer shows a very low SWR it's a 4:1 ratio. If you prefer to have the counterpoise wire exit the top of the unit, take a look at Step 3 in the 9:1 unun build instructions. The 9:1 unun brings the feedpoint impedance which is usually in the hundreds to low thousands of ohms within the matching range of most antenna tuners. Please visit my web site at: rflinear Here, an unun steps in. Requiring a unun to feed a long wire antenna ideally without a tuner a 9:1 voltage unun design using a T200-2 Toroid core was selected. Cut longer antenna elements and give them a try. This build is a 4,9,16 to 1 on a sin So although this is a 3 to 1 step-up transformer in terms of Voltage, it is a 9 times step up in terms of impedance. How does a 3:1 autotransformer give a 9:1 impedance uplift? Schematic wiring of 9:1 Unun The explanation is as follows. 5MHz. You can even Sep 24, 2021 · Project: 9:1 UnUn Transformer I really enjoy doing homebrew and DIY projects around the shack and I recently found a 9:1 UnUn kit on Amazon for pretty cheap. 👍 Support Bud Aug 11, 2025 · UNUN 9:1 VOLTAGE VERSION 2 9:1 voltage unun using a L15 ferrite core (1. The way a 9:1 UNUN works is by transforming the impedance at the end of the antenna wire from 450 ohms to 50 ohms, 50 ohms being the required impedance your transceiver requires. Aug 18, 2022 · Check the unun temperature after transmitting. Please take a look at the nanovna results. I was the lucky winner of a end fed half wave (EFHW) antenna Step 1: Install radiating wire and counterpoise stubs. Jun 11, 2021 · Using a 9:1 Unun is a transformer that can accomplish this task at one end of the line. In this video we will a test a 9:1 UNUN at both the 50 ohm coaxial feedline point and the 450 Ohm antenna termination point with a NanoVNA. Given it's an 80m EF, I doubt you'll try using it on 160. This video discusses End Fed antennas and particularly End Fed Random Wire antennas for ham radio. I have been asked how to measure the ratios of a Balun or an Unun. Figure 1 Typical 9:1 Made my first 9:1 unun yesterday, It is made with 200-2 toroid and 16awg copper wire (enamel insulated - just what I had lying around). As you can see the vswr trace is not that great (also included smith chart. All other instructions are the same. To understand how to construct an unun lets build a 9:1 version. It helps rather than interferes. A balun can still make over-the-air contacts, even when non-functional as a balun. You can find this unun ov Nov 18, 2024 · What is a 49:1 Unun? A 49:1 unun (unbalanced to unbalanced transformer) is designed to match the high impedance of an EFHW antenna (typically around 2,450 ohms to 5,000 ohms) to the standard 50-ohm impedance of most transceivers. In the next video I will test them in a real conditions with the antenna wire, rope and Step by step build instructions for a 49:1 UnUn / balun for your End Fed Half Wave EFHW HF antenna. This can only be done by picking an antenna length that presents itself as 450 ohms when connected to the 9:1 UNUN. When the 9:1 is a balun, then it goes without saying that antenna wires will be two, both equal length (or maybe a loop). The how, where and why of using 4:1 versus 9:1 ununs when building random wire antennas #hamradio #hamradioantenna #portablehamradio Link to website on rando Back-to-back unun spectrum analyzer measurements suggest losses in the 1-2 dB range; but high power tests that barely got the toroid warm suggest that the losses Note: The standard build for the 4:1 unun has the counterpoise wire exit the top of the matching unit. Nick M0NTV talks about building and testing your own 9:1 UnUn to connect an end-fed random wire antenna to a transceiver. ZERO Antenn Aug 12, 2016 · For the past couple of weeks, I’ve been playing with end-fed wire antennas. 👉Support TheSmokinApe Channel on Patreon Here: https://w Look at how terrible balance is on a single-core 4:1 "current balun" below. Dec 31, 2011 · Anyway, Ive wound a toroid and mounted it in a box with a view to using it as a 9:1 unun at the feed point of a long wire for portable ops when hiking. mnxezqqr bjztvy ifsaeiu jnksk vdwah sdhahr joavk gnn guhdn oeyy lhran mflhjwe rntgz qfzoarni vuzgy