Well Eric, looks like no one knows or no one is interested. As a collector of post WWII am-fm radios I would like to know more about this as well. I am well aware of the “general” and his underhanded tricks and manipulations regarding the move of the fm frequencies. In my opinion that “man” was reprehensible. Nevertheless, it’s old news now. I wonder even if there were any fm broadcasts in Canada at the old frequencies or any available within reach of the American border.
Regarding the first generation of fm-am radios (I have a Philco console circa 1947 and a Zenith mantle and I have found them to drift outrageously all during listening tests. Of course they are both pre AFC
I haven’t gotten around to experimenting with NPO caps yet but may do so when I get the chance. The amazing thing is I also have a next generation Zenith mantle radio with an AFC tube in it and it locks onto just about any fm signal it finds. What a difference