Available as a Unun for 50 ohm coax to 75 ohm coax or 75 unbalanced load or as a Balun for 50 ohm coax to balanced load such as a low (less than a wavelength high) dipole with either side eye bolts and halyard hoist or as post mountable top studs output.
This is an impedance transformer for 50 to 75 ohms and may require a additional feed line choke to keep common mode current off the coax braid.
CB-1.5-1500EB is useful for a dipole center feedpoint for low dipoles with 75 ohm antenna impedance.
Top stud version also useful for 75 ohm ladder line to coax interface
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