Many servicemen have requested information about numbering of FM dial scales on 1942 Philco radios, and why these radios will not cover the current [88-108mHz] FM band.
The 1942 models have dial scales numbered from 25 at the left 100 at the right. These numbers correspond with the FM frequency band used at the time by the use of a simple system.
The frequency range of all 1942 FM radios produced by Philco was from 42 to 50 mc [mHz]. This range was indicated on the dial scale by dropping the first numeral and all decimal points of the frequency. Thus, an FM station broadcasting on 42.6 mc. would be tuned to 26 on the FM dial — because 42.6 without the first numeral (4) and without the decimal point is 26. A station at 45.5 mc. would be tuned to 55 on the dial, 47.1 mc. at 71 on the dial, and 49.9 mc. at 99 on the dial.
From Philco Service and Accessory Merchandiser – November, 1948, Vol. 1, No. 4, Page 3.