9:1 Baluns are useful between 450 ohm balanced lines for center fed Zepps and G5RV antennas where the impedance at the end of the feedline is 450 ohms (1/2 wavelength feedline), or high impedance feeds for log periodic beams.
9:1 Ununs are useful between coax and long wires with load impedances near 450 ohms. Shortwave listener antennas also can benefit with the 9:1 unun and it will provide a better match than 4:1 ununs – this means quieter noise levels and stronger signals so you can hear distance stations easier.
9:1 (450:50) 250 Watt Balun/Unun Kit
Model BA-9-250 is a 9:1 balun kit used to translate a 50 ohm input up to 450 ohms at RF power levels up to 250 watts continuous (500 Watts PEP) when used with a matched load. With a matched 450 ohm load the SWR over the frequency range 1.8 to 30 MHz is shown in the following table measured with an AIM 4170 network analyzer. Notice that the conversion from 450 to 50 ohms is very consistent from 1-31 Mhz and SWR is less than 2:1 over most of the range allowing easy tuning by most radio internal antenna tuners or an external tuner. Graph is for a 9:1 unun often used with long wire or end fed antennas.
The kit consists of a F140-61 ferrite toroidal core, three colors of 1000 volt insulated wire, a UHF connector with stainless steel hardware, and an instruction manual with directions to connect the kit as a 9 to 1 balun (balanced antenna to unbalanced coax) or 9 to 1 unun (unbalanced coax to unbalanced antenna).
+$10 S&H. Tax in Calif.
Note: S&H is “per order”. Order more than one item or add other items and S&H remains $10.