This circuit can also operate with SW and even VHF signals up to 150 MHz. The circuit can be inserted between the antenna and the receiver. XRF is a 10 mH choque. This component can be a home made version. It consists in 100 to 200 turns of 32 or 34 AWG wire on a 100 k ohm x ½ W resistor. Power the circuit by cells, battery or a Power supply. Current drain is about 20 mA.