GE prewar FM tuner covering 42-50 MHz.

Today marks the official 70th birthday of the modern FM band, although pinning down an exact date for its birth is a bit more complicated. On Friday, October 26, 1945, the FCC announced the official moving day of December 1, 1945, with normal programming on the higher frequencies to start on January 1, 1946. On that date, all existing FM stations were required to begin equipment tests on the new band, although there were already three FM stations operating on those higher frequencies. At the time, 600 applications were pending, and 64 applications had been conditionally granted.

The old FM broadcast band had been set at 42-50 MHz.  The new band was originally assigned as 88-106 MHz, two megahertz smaller than the current band.  The top two megahertz were originally assigned to facsimile broadcasters, although that assignment was never put into place.  There was also talk of extending the band down to 78 MHz, and many early receivers tuned 78-108 MHz.  Because of the transition, many early FM receivers covered both the old and new bands.

A number of stations had announced that they wouldn’t be able to meet the deadline, and the FCC had announced that it would be lenient for stations having justifiable equipment problems.

The entire story of the move to the new band could fill a book (in particular Man of High Fidelity by Lawrence Lessing or  Empire of the Air by Tom Lewis).  Much litigation and legal wrangling followed, which mostly served to further delay the widespread adoption of FM.  But if we need to set a birth date for the modern FM band, December 1, 1945, is as good as any.

References

• Billboard, Nov. 3, 1945
• Radio Craft, December 1945
• The Tragic Birth of FM Radio
• The Birthplace of FM Broadcasting, Alpine, N.J.

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