Yaesu M-90D is equipped with both a round 8-pin jack and an 8-pin modular jack. Supplied microphone cable (round 8-pin to 8-pin modular) can be connected to either jack of the M-90D in accordance with the microphone jack of the transceiver. The M-90D does not require the SCU-53.

The M-90D microphone utilizes a dynamic microphone element that is finely tuned to deliver rich low to mid-frequency responses desirable for a clear and concise conversation. Using a windscreen cover and a directional microphone element, the structure of the microphone of the M-90D is designed to concentrate voice input from the front while reducing ambient noise from the side. Built-in Low-Cut filter creates clear and crisp audio characteristics by shaping the low-frequency response (cut off at 340Hz, -6dB/octave). An isolation transformer is integrated into the circuit board in order to enhance the audio quality. The M-90D is compatible with all YAESU HF transceivers equipped with the round 8-pin microphone connector or the 8-pin modular microphone connector.

M-90D is a desktop microphone. The PTT of the M-90D uses three Air-Cylinder tubes similar to the Reference Microphone M-1. This provides solid and smooth extended operation. A simple one-touch PTT keylock button is placed directly above the PTT key for those long rag chews.

*M-90D does not require the SCU-53 to connect to the transceiver equipped with the round 8-pin microphone connector.