AM/FM mono radio information

[Tom Bavis]

Almost all FM tube radios used miniature tubes, as they were introduced about the same time as the modern FM band, and the smaller size is better for high frequencies. I have a 1946 radio that usees MOSTLY octal tubes - the RF amp stage being an exception. Zenith and Stromberg Carlson made some of the better early FM radios - many Stromberg schematics on my website: http://www.audiophool.cjb.net/MadeInRoch.html

The 12SA7 / 12BE6 converter tube used in AM radios makes a LOUSY converter at 100 MHz, but some used it anyway. A much better circuit is the dual triode oscillator/mixer, using 12AT7, 12DT8, 17EW8 - tubes designed for high frequency use.