Angelo,
There are a number of different factories that produce microphones for Baofengs.? I have bought 6 of them so far and everyone is made differently. I had one that didn't work at all on the QMX, so I got the mic element from DigiKey that Hans mentioned on the QRP Labs website, and replaced the one in the Baofeng mic with it. I found that another Baofeng mic worked just as well as that mic element from DigiKey. I did have to cut off the connector and rewire a new stereo connector, so the ring to ground is the mic connection, and the tip to ground is the PTT connection. I just isolated the speaker wires and I'm not using the speaker. It is only 8 ohms anyway and the QMXs work better with at least 32 ohms.
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73, Dan - W2DLC
Daniel Conklin