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.
A simple ferrite ring filter on the DC power line can help suppress the RFI noise affecting the victim device or keep the DC power cord from acting as an antenna and radiating RFI into other victim devices. This kit is also useful on laptop computer supplies, routers, cable modems, wireless phone charges, etc.
Installation is quick and easy: Just wrap the DC power cord through the center of the ring filter as many times as you can and reinstall. For best results with long DC power lines, use one at the ring filter at the wall wart end (to prevent the wall wart power supply from using the DC line as an antenna) and another at the DC plug end (to prevent the electronics in the powered device from using the DC power cord as an antenna). Typical installation is shown below:
The filter suppresses RFI in from .1-100 MHz. Inside diameter is 3/4 inch/19 mm.
Since most households and office environments have multiple wall warts we offer the Wall Wart RFI Filter kit in bulk quantity packages.
Known RFI Generators include Roku/Sling-TV power adapter - Interference heard in the AM broadcast band and harmonics. Also many ethernet Cable/DSL modems, cell phone chargers, computer power adapters have the same issue: using the AC or DC side of the power supply as a radiating antenna. RFI solution is to use a linear power supply, change adapters or wall wart ferrite filters