 However, stations that are 10.6 or 10.8 MHz apart (near the typical 10.7 MHz intermediate frequency of FM receivers) must be physically separated by 10 km to avoid causing interference in nearby radios.WZBZ's transmitter site is 2 km from that of WAJM (88.9 FM), and moving to 99.7 would separate the two stations by 10.8 MHz.Press' contention was that the frequency swap was possible, since WAJM's license expired in 2006 and it was legally nonexistent – and it did not file for renewal until after WBHX's application, four years later.