Simple answer: it doesn't! 200-300 referred to FM channels, not frequency. If there is a "kHz" under the FM channel range strip, it is either a misprint or you are seeing things that aren't there. (I suspect the latter, since the "Hz" designation didn't come into use until the early 1960s.) The FM frequency range coverage of your '47 Crosley is the same as contemporary sets sold in the USA. Said range was established by the FCC immediately after WW2 had wrapped up. "Channelization" of the FM band never caught on as a concept in the US and was quietly abandoned.