I am searching for a source of information for an old desk stand model Shure Brothers microphone. The model number is '70ST'. It appears that it was used for amateur radio.
The 70ST was introduced in 1939 at $25.50.
The catalog description was: "Here's the world famous Shure Super-Level Crystal Communications Microphone. Has Shure high-efficiency speech characteristic with the highest output available in a crystal microphone: 26dB below 1 volt per 10 bar speech signal. Diameter 3 3/16". Depth 1 3/8". Satin chrome finish. 3 1/2 lbs. Complete with 7 ft. shielded rubber-covered cable and S36A Iridescent Gray Desk Mount."