Balun One Nine v1 - Tiny Low-Cost 1:9 HF Antenna Balun and Unun with Antenna Input Protection for Ham It Up, RTL-SDR, HackRF and Other HF-Capable Radios. Great for DIY Dipole and Longwire Antennas

nice balun i ised it when i started my ham radio hobby

This balun from Nooelec works perfectly with my long wire. I had a problem with noise coming down the coax from the house. Cutting the trace on the backside of the board lifted the center tap ground on the secondary and stopped the noise. I think I had current flowing to the ground rod which put noise into the received signal. I now have a true isolation transformer and better reception.

Interesting piece of hardware for using a random-length wire with an SDR-RTL but there's more to this. First, this is not, technically, a BALUN (BALanced-UNbalanced line transformer), but a UNUN (UNbalanced-UNbalanced line transformer) The picture I've added shows a standard circuit diagram for a 9:1 UNUN. You'll notice a couple things about this. First, how SMALL the NooElec unit is. Second, one side - the UNbalanced side - has twice as much impedence as the side to ground. This makes a difference. Your VSWR is lower when wired right (I tested it with a SARK 110 vector analyzer, a "random" 36 foot piece of 22 gauge jumper wire - see the other two pictures attached, the one marked CSV_001 is wired correctly, CSV_000 is wrong). While the differences are small in my example, other wire lengths at other frequencies can make a HUGE difference. The side with the paperclip goes to ground. You can test this out yourself if you look at the circuit diagram. One connector shorts directly to ground. The other side has some impedence. I measured - roughly - 5 Ohms with a Fluke 118B digital multimeter). From Balun designs dot com: How long a wire to use? While you CAN use a "random wire", 100 years or so of Hams experimenting and calculating have figured this out for you - it's settled science although things like height of the wire above ground and its proximity to telephone wires or home wiring will alter VSWR too so your lengths may need to be a little different. The effects on receive may be marginal on some frequencies depending on your wire length but can make a huge difference on others; transmitting with very high VSWR can be impossible or damage the transmitter, but, since we're not using this particular UNUN for a transmitter, this is FYI only. Balun Design dot com has a link to a wire length chart you may find useful (fourth picture): http://www.balundesigns.com/content/Wire%20Lengths%20for%204%20and%209-1%20ununs.pdf "unun should be used with the wire lengths listed in the table shown in the above link. Use of the 9132 for "random" wire lengths, other than shown, can potentially create an impedance that is too high for an ATU to match. If a wire length not shown in the table is installed, an antenna analyzer should used to determine the actual feedpoint impedance that will require matching for each band of operation." "Ununs are intended for use with unbalanced antennas such as verticals and long wires. They will not work with balanced designs such as dipoles or loops and use with a balanced antenna may cause erratic operation and/or damage to the unit." One side to wire, one side to ground. Hope this helps.

works well enough for my NOOELEC HAM IT UP - I'm not sure it's absolutely necessary for receive with my upconverter - being a bit "anal," I ordered it - no noticeable improvement though using the balun in receiving RF signal, well none that I can discern - if interested, I did run this on transmit at 10 watts and it held up (40 meters, ant. tuner and VERY brief exposure time to 10 watts) - if you're going very high with your dipole, (mounting in excess of 50') maybe even transmit at 5 watts or so (and I'm not endorsing transmitting on this) then it may add something to receive levels (I was at 20' and again, no noticeable difference in receive gain) - I have approx: 100' of ant. on this unit and balanced dipole - haven't yet though, but I intend at some point to try OCFD and the correct length just so see if there's any difference with a resonant ant. on edit: 2/14/2016 After reading another review here, (Tom Paine's thorough review) I decided to try changing from a OCF dipole to a long wire and "ground." I was doing OK, but changing the configuration does seem to have made a difference. I didn't measure it but did compare receive signal strength as quickly as I could make changes to make the comparison. It's somewhat better as Tom related in his review, with the "long wire" on one side and a good ground.

I had a 100ish foot long wire antenna that I used for shortwave reception and while I was recieving more than the built-in antenna on my pl-880 it was still a lot less effective than I Expected. I know this isn't the normally expected application but I put the balun into a waterproof T box one side attached to the long wire and the other to a ground rod and all of a sudden my reception improved dramatically. This is a great cheap way to enhance a listening antenna.

For my use situation, I really couldn't see much difference with or without. My "longwire" was inside ... maybe 25 to 30 foot. I cut the trace, no change. The spring clips on the terminal were not real strong but are working ok. I'll try with a longer wire latter this summer.

It improves the signal-to-noise ratio (SNR), which is crucial for listening to weak signals

I have an Sdrplay RSP1, which I was previously feeding with a 40 meter dipole. This worked very well, but wanted to try a random/long wire antenna to see how it compares. I am using 100 feet of wire with a 40 foot counterpoise. To feed an end fed wire you need an UNUN. From the factory this is a balun (9:1 baluns are used with a dipole+400 ohm ladder line), but can easily be converted for an unun. You simply need to cut the small trace on the back of the circuit board. It will be very obvious what I'm talking about when you're looking at the thing, as there is only one. Then you just attach your random wire and counterpoise and are good to go. Note: performance WITHOUT a counterpoise was noticeably worse. I also tried it with the trace intact as it comes from the factory and performance was noticeably worse than with it cut. With the wire 20 feet in the air and the counterpoise stretched out along the ground I can hear the world. I'm very happy with this balun/unun, but the trace must be cut to get proper performance out of a long wire with it as it comes from the factory.

Buena calidad de fabricación, robusta y sencilla de conectar. Cumple su función sobradamente. Como balun para antenas tipo Yagi ya sea comerciales o de fabricación propia, permite adaptarlas a los receptores SDR con facilidad y gracias a su pequeño tamaño se pueden proteger de las inclemencias del tiempo en pequeñas cajas impermeables adosadas a la propia antena.

"Balun" ist das Kunstwort aus "BALanced-UNbalanced" und kennzeichnet Transformationsstufen, welche symmetrische Leitungen (z.B. UKW-Flachbandkabel) auf unsymmetrisch (z.B. RG58-Koaxialkabel) anpassen sollen oder auch den symmetrischen Ausgang einer Loop-Antenne an unsymmetrisches Koax. Wenn man anfängt, einem ursprünglichen Balanced-Signal "Ground", also Erde hinzufügen zu wollen, dann verschiebt man die komplette Philosophie einer symmetrischen Speisung in Richtung Rauschen. Wenn man aber einen Langdraht benutzt, macht das Teil schon Sinn, mit dem Anklemmen einer Erde muss man experimentieren. Bei einem separaten Staberder mag es noch angehen, schliesse ich aber eine Erde aus dem häuslichen Bereich (Metallrohre, wie Wasser oder Heizung) an, dann ziehe ich mir UNWEIGERLICH den häuslichen EMV-Störnebel in den Empfänger und der Rauschflur wird unangenehm. Selber bin ich komplett weg von unsymmetrischen Systemen und benutze nur noch eine 70 cm-Loop für AM von Mittelwelle bis hoch zu 30 MHz, die geht mit einer symmetrischen Leitung (DSL-Rangierdraht) vom Speisepunkt bis direkt an den SDR-Eingang. Damit höre ich in Samao, Fiji und Papua-Neuguinea das Gras wachsen. Tip für alle Langdraht-Fans: Einfach zwei Drähte (max. 8 Meter lang) jeweils an die Balun-Klemmen dran, gerade nach Links und rechts gespannt, evtl. auch im Rechten Winkel je nach Platz, am Ausgang des Balun ein Koax dran und nach evtl. Filtern rein in den SDR-Eingang. Der Empfang ist erdfrei und zehnmal rauschärmer als "irgendwie eine Erde" dazu zu klemmen. An eine Loop kommen allerdings Langdrähte nie ran, weil sie die E-Komponente des elektromagnetischen Feldes empfangen, und damit die EMV-Störungen, die auch meist das E-Feld verseuchen. Eine Loop empfängt nur das H-Feld, und dort ist der Rauschflur extrem gering, weil die Störungen des häuslichen Nebels kaum das H-Feld beeinträchtigen.

Great little item that appears to do exactly what it is supposed to. I have used it to match my long wire antenna to an SDR and all appears fine. Unsure of the technical details of the Balun, so I leave that to better informed individuals to provide... Overall very happy!

Being in the market for a balun for some time now I finally broke down and bought the NooElec Balun 1:9 which filled the bill perfectly! After doing a month of do diligence in the search for the ultimate Balun for RTL-SDR radio reception use. The quality is absolutely first rate in form, function and finish. The best parts on a top quality PCB (nice and thick) which makes for a thoroughly functional & high performance Balun for SDR radio 'reception'. As such, it CANNOT be used on a transmitter as you'd fry it in one hell of a hurry, so don't even try! It's small size belies it's Superior abilities. It even has circuit protection Built-in. Therefore your radio is safe in the event of an ESD-type of ingress into your radio. A nice consideration! Also, it's made in Canada and the USA! The price is just right, and the form factor perfect for the DIY'er who likes simple and quick mini radio related projects to do. This was my first and successful try at making a suitable waterproofing closure for my new 1:9 Balun which was surprisingly easy, using PVC plastic parts that anyone can purchase at the hardware store or builder's supply. And at ONLY $15 US, it was an absolute no-brainer. I know I'm going to be buying one or two more of them for use in different configurations. Yes, you can't go wrong with NooElec as I'm quickly finding out! First Rate & Top Drawer . . .

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