These baluns and ununs can be used for impedance matching and also as End Fed halfwave antenna matching transformers to 50 or 75 ohm coax cable.
AC/DC Generator RFI Noise Filter Kit - 3" ID - 2 filters
The RFI generator kit includes 2 ring filters with 3 inch inside diameter for 2 or more turns of AC/DC generator cable at generator and another 2 or more turns through center at the end of the generator cable near the powered device. The filter near the generator isolates generator power cable and prevents it from acting as an RFI antenna (generator source) and the filter near the powered device prevents the powered device from using the generator cable as an RFI antenna.
Use 2 or more turns through the filter for higher RFI suppression than a single turn (2 turns is 4 times the suppression as 1 turn, 3 turns is 9 times a single turn, etc.)
If you have a generator cable less than 1/2" diameter, consider the RFI-GEN-1 generator filter with a 1" inside diameter.
Note: generator cable not included.