The Yaesu MD-100A8X desk mic features a cardioid dynamic mic element. It features UP-DOWN tuning (on compatible Yaesu transceivers). There is a scan switch, a switch for PTT (push to talk) and also a lock feature. The frequency response is 100 to 5000 Hz. Sensitivity is -75dB (0 dB=1 V/0.1 Pascal). Impedance is 500 ohms unbalanced. Weight is 24 ounces (670 grams).
On the bottom of the mic base there is a High Emphasis switch and a Low Cut Switch. The mic comes with a special "reversible" cable that can terminate to a Yaesu 8 pin mic plug or a Yaesu modular plug (for FT-857/897).
This mic works well with the FT-450, FT-450D, FT-840, FT-847, FT-857/D, FT-890, FT-897/D, FT-950, FT-990, FT-1000, FT-1000MPV and FT2000. It does not work on some older Yaesu transceivers such as the FT-757GXII and FT-736R. Please also note that Yaesu desk mics such as the MD-100A8X will not work on Yaesu mobile radios due to differences in impedance.