The Earliest FM radios
The first FM radios (other than experimental ones made in Armstrongs lab) were made by General Electric.
The very first was a series of 25 radios commissioned by Mr. Armstrong for field tests and had a frequency
range of 41-44 mhz. These GE radios cost $400 each and were built very early on in 1938. The order went
in late 1937.
I am not sure if they were assigned a "model number" but the example shows Cat. 5100997. These
radios were not very asthetically pleasing and looked more like they really belonged in a laboratory
setting. Obviously, they used an external speaker of I'm sure very high quality.
Images courtesy of Mike Katzdorn
The next FM radio GE made was the 1939 GM125. This was a large console model with the radio within a lid
on top of the set. When closed, it looked like a large speaker. It was FM only as well and was used
primarily for field testing in peoples homes. It had a tuning range of 37-44 mhz
For 1940, GE came out with two models. The table model HM80 and the console HM136. The HM80 is FM only
like the GM125, however the HM136 had the AM broadcast band as well as Shortwave bands. The FM tuning
range on these was 39.5-45 mhz however, the Riders manual vol. 11 shows the HM136 to have a tuning range of 39-44 on the FM band.
This image is of a GE HM-136 from the cover of Radio-Craft Magazine, July 1940
Meissner introduced an FM radio around this time as well. It had a tuning range of 39-44 mhz. Stromberg Carlson was also one of the first manufacturers to introduce FM to their
radio line with about 4 models with an FM tuning range of 40-44 mhz.
This Stromberg Carlson model 435M was made just after the band was set to 42-50 mhz. The service literature on this model states that it tunes from 40-44 mhz.
I'm sure there are more radios that could be shown here regarding the earliest FM radios, but this is all that I know about at this time.
By mid 1940, the FCC had established the FM band at 42-50 mhz. Many radio manufacturers jumped on the FM bandwagon and by the time the U.S. converted to wartime production, over a hundred different models by over 25 different companies were made.
During WWII, The FCC was pursuaded (Mostly by David Sarnoff of RCA) to move the FM broadcast band to 88-108 mhz. This caused all these FM radios to be obsolete! Armstrong fought back and managed to get the 42-50 mhz slot back. At least for a few years untill the new band got established.
A number of converters were made for the Prewar FM radios with varying degrees of success, but more of that can be found here. All FM radios made after WWII have the 88-108 mhz FM band, however, some companies (particularly the ones with an Armstrong FM license) produced radios with both the old and the new FM band. These include General Electric,
Magnavox, Stromberg Carlson and Zenith. By 1949, the new FM band was well established and the old one was abandoned. The last FM radio I have found with both bands is a 1949 Zenith console.