The FRT-7700 is an ultra-compact antenna tuner for the FRG-7700 receiver. Designed for operation from 150 kHz to 30 MHz, the FRT-7700 will provide the proper impedance for the receiver, thus rejecting unwanted signals . A built-in attenuator, 60 dB maximum, prevents intermodulation and cross- modulation from occurring when strong signals are being carried to your receiver. Also, a two-section lowpass filter aids in the rejection of interference from strong signals above 2 MHz, when you are listening to bands in the 150 kHz to 500 kHz range.