B11 ISO: The RadioWavz 1:1 Choke Balun is an Isolation transformer. This transformer acts as a RF isolator reduce or eliminate stray RF often found on coax. Power is radiated by the antenna not the feedline. Also known as a Sleeve Choke. The Isolation transformer is effective from 1.8 to 50 MHz. The BALUN is designed to handle full legal power (1500W SSB and 200W CW).