Okay, im just going to put it out there. If you speak louder into the microphone, we are not going to hear you better. Just stop. Thats not how this works. In fact, the louder you are, the worse the quality is. Again, it doesn't matter what radio you have nor what microphone you have, if we are having trouble hearing you due to a poor signal or some technical issue, yelling at the mic doesn't help.
There are exactly 2 times when yelling at the mic is appropriate. One is when the ambient noise level is high and you are trying to make your voice more distinguishable from the background. The other is when you DON'T key up, but you are yelling at the dummy on the other end. In both cases, I recommend you put the mic down and come back to the radio when the issue subsides.
I hear this everyday I'm on the radio (and no, it's not because I am the one yelling at the radio). That is why I mention it.