The T-45 microphone can be used with most war time American radios such as the BC-1000, BC-1306, GRC-9. The microphone is normally used along with the HS-30 headset and SW-141 PTT switch. The T-45 microphone is a carbon type Noise Canceling microphone designed for operation on a nominal current of 50 miliamps. The resistance of the unit is between 50 and 125 Ohms at 1000 cycles per second. Frequency response is substantially flat from 200 to 4000 cycles per second. The microphone is worn close to the operator’s mouth and responds to his voice. However sounds originating farther away, such as background noise or battle noise, are cancelled in the microphone because of its differential type of construction.
The complete microphone without the PTT switch.
This is the way to attach the microphone.
A kind of muzzle. Not convenient for smokers.
Side view of the device. The thin wires are to fit it around the ears of the operator.
Front view,made in 1944.
The rear (talk) side, behind the slits is the microphone. What's in the grooves is not definable, maybe the previous owner had a cold.
Plug PL-291-A. The plug was used for several types of microphones in order to connect to the PTT switch.
Complete, it looks like this.
This is the PTT switch SW-T 141, with leather carrying strap and cable CD-318 with PL-68 plug and jack JK 48.
Made in 1944 and in 1952 once more moisture and fungi-proofed.
SW-141-T. The PTT switch can be locked, which was for people who talked much and got cramps in the fingers.
Jack JK-48 which was connected to PL-291-A
With plug PL-68 the assembly was connected to the transmitter.