RCA MI-6225

This carbon microphone appears in the RCA catalogue in 1936 but not in 1939.

A similar microphone was sold by General Electric (GE) as model P-64713. Sadly our exhibit has lost its badge so we don't really know if it was originally labelled as an RCA or a GE microphone.

From the RCA catalogue of 1936, Page 10

RCA DOUBLE BUTTON CARBON MICROPHONE

For microphone applications where good performance at the lowest possible price is an essential, the RCA Double Button Carbon Microphone is ideal. Attractive appearance, smooth frequency response, low carbon hiss— these are qualities that make this microphone outstanding. It is mounted in handy, rugged, all-metal case, suitable for either desk or hand use.

MI 6225-A - Code TUGEJ. $11.50

SPECIFICATIONS

Type: Two-button carbon-grain.

Frequency Range: 50 to 6,500 Hz.

Output Level:-63 db. (10 bar signal, open circuit).

DC Resistance: 200 ohms per button.

Impedance: 250 ohms.

Excitation Voltage: 4 to 6 volts.

Dimensions: 6" high, 3½" wide, 2" thick. Net Weight-2 lbs.; Shipping Weight-4 lbs.

A post about the RCA and GE double button carbon microphones at the Coutant website.