RF Toroid Calculator by VK3CPU
50:450 ohm (9:1) Balun or Unun Core Kit, 1.8-30 MHz, 250 watts PEP, end fed, T2FD antennaProduct DetailsInput ohms/Output ohms: 50 in, 450 outFrequency Range < 2:1 SWR (MHz): 1-31PEP Power Rating (watts): 250Model BA-9-250 is a 9:1 balun/unun kit (assembly from parts supplied required) 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.
Radio Club idea:
Buy 10 for a club do it yourself construction project - you can learn something about winding impedance transformers and also build an end fed antenna (just add wire).
Typical SWR curve for this project:
Tutorials
50:450 ohm (9:1) Balun or Unun Core Kit, 1.8-30 MHz, 250 watts PEP, end fed, T2FD antenna
Product Details
Input ohms/Output ohms: 50 in, 450 out
Frequency Range < 2:1 SWR (MHz): 1-31
PEP Power Rating (watts): 250
Model BA-9-250 is a 9:1 balun/unun kit (assembly from parts supplied required) 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.
Radio Club idea:
Typical SWR curve for this project:
