What kind of microphone is this and how do I use/bias it?
Now that it seems certain that you have a dynamic microphone, let's have a look at what your DRA818V module needs at the microphone input.

On page 3 of the datasheet, there's a table of radio characteristics:



Down towards the bottom is this line:


  Sen_MOD  Modulation Sensitivity @1KHz at 2.5KHz Fdev.  10mV


That's telling you that a 10mV peak to peak signal applied to the microphone input will result in 2.5 kHz of deviation.  That's the maximum deviation when using a narrow channel.  It isn't clear if you need a stronger microphone signal for full modulation on a wide channel. (It also tells you that this specification is tested using a 1kHz audio test signal.)

What that means is that you need at most 20mV of microphone signal going into the DRA818V to get the maximum possible transmit deviation.  That means 20mV to get your spoken voice from the transmit side to maximum volume on the receive side.

What you need to do is to capture your spoken voice on the microphone with your oscilloscope, and measure its peak to peak voltage.  From that you figure out how much amplification you need to get to 20mV peak to peak.  That shouldn't be much, maybe a gain of 5 to 10.

If your microphone amplifier has too much gain then it will sound distorted on the receiving side, but you won't be breaking any regulations.  The transmitter will (should) clip  the transmit audio to keep your modulation within the allowed limits.

You might not need any amplifier at all for the microphone.  Just connect it straight to MIC_IN and ground and give it a try.  I expect the bias you mentioned in comments interfered with the microphone and caused the output to be too weak.