Off Center Fed (OCF) Antennas

50:450 ohm (9:1) Balun or Unun Core Kit, 1.8-30 MHz, 250 watts PEP, end fed, T2FD antenna

SKU BA-9-250
In stock
Product Details

Model BA-9-250 is a 9:1 balun/unun kit used to translate a 50 ohm input up to 450 ohms at RF power levels up to 250 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.

BA-9-250 Graph

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OCF antennas are very convenient as they will allow multiple bands of operation with a simple wire antenna which is fed off center with a 4:1 OCF Current balun with built in feed line choke,