MFJ-269C Antenna SWR Analyzer
MFJ's line of antenna analyzers are extremely popular due in part to their simplicity and ease of use. One feature is the ability to attach an antenna and get a rough idea of its center frequency and usable bandwidth among other things. This necessitates the injection of a small signal in order to make these measurements that may be heard nearby.
500 kHzKiloHertz (kHz) 10^3 Hz - 500 MHzMegaHertz (MHz) 10^6 Hz