Review on NooElec Balun One Nine Applications by Chris Doe

Interesting hardware to use any length cable with SDR-RTL, but that's not all. First, it's not technically a BALUN (Balanced-Unbalanced Line Transformer) but a UNUN (Unbalanced-Unbalanced Line Transformer). ) The image I've added shows the standard UNUN 9:1 schematic. You'll notice a few things about it. First, how SMALL the NooElec block is. Second, one side - unbalanced - has twice as much resistance as the side facing the ground. Is it important. Your SWR will be lower when properly connected (I tested it with a SARK 110 vector analyzer, a "random" 36ft piece of 22 gauge jumper - see the other two pictures attached, one with connected correctly to the designation CSV_001, wrongly connected to CSV_000). While the differences in my example are small, different cable lengths at different frequencies can make a HUGE difference. The side with the paper clip is grounded. You can check it yourself if you look at the schematic. One terminal is connected directly to ground. The other side has some resistance. I measured - around - 5 ohms with a Fluke 118B DMM). From balun designs dot com: What wire length should I use? While you CAN use "random wire," about 100 years of experimentation and ham radio calculations have figured this out for you - it's an established science, although things like the height of the wire above the ground and its proximity to phone wires or household wiring will change that VSWR. also, so your lengths may need to be slightly different. Depending on the length of your cable, the effect on reception can be negligible on some frequencies but can be huge on others. Very high SWR transmission may not be possible or damage the transmitter, but as we do not use this specific UNUN for the transmitter, this is for reference only. Balun Design dot com has a link to a wire length chart that you may find helpful (fourth image): http://www.balundesigns.com/content/Wire%20Lengths%20for%204%20and%209-1%20ununs. pdf "unun should be used with the cable lengths specified in the table above. Using the 9132 for 'random' cable lengths other than those shown may potentially create an impedance that is too high to match the ATU. If the cable length is not listed in the table, an antenna analyzer should be used to determine the actual feedpoint impedance, which must be matched for each operating range."Ununs are designed for use with unbalanced antennas such as vertical and long wire. They will not work with balanced designs such as." Dipoles or loops and not used with a balanced antenna may cause malfunction and/or damage to the unit." Fire, one side grounded. Hope this helps.