Review your schematic...
The power you see as negative, is rectified power from the RF coming into the Amp from your radio. Note the unbanded side of the diodes on the input ACROSS to a set of caps - they provide the working mechanism for the amps Class C operation.
The Gates themselves just need a field effect or voltage presence - can be positive or negative, so as the carrier power develops - the incoming unmolested power that is RF passing thru the, now - slightly negative, voltage bias presence - helps the transistor "transition" from on to off state.
What is nice about this method is the effort to keep the ratios of power in both negative DC range (BIAS) and the positive drive level RF is (in reference to ground) from skewing the transistor and causing a latching issue from too much positive drive on an ,AC waveform.
Without this offset, it can generate an FM effect - the reverse bias the diodes create is short lived and only exist as a ratio of power - as in - the Rectified negative region to the positive RF level of drive - so the Gates don't see a ton of RF power and possibly damaging the gates from perforation (puncture) thru into the substrate - making it a dead short instead.
So, you asked about Mic's...
Well, Mic's can be found in two categories,
One called Dynamic - generate their own signal as an AC component and are very low-level - like 600mV (about 0.6 VAC) - Dynamic sounds more "official" than "Generates their own power".
Another is Electret - they use power called BIAS - it's essentially a voltage with very low-current behind it - the Element in an Electret is a membrane over a fixed plate - and then you talk the membrane vibrates and changes the distance it has to the fixed plate - making it act like a variable capacitor - an FET amp inside the Element detects this and amplifies the effect (your voice) as a ratio of power in to power out - per the IMPEDANCE the source of voltage is to power the device.
So ...
Dynamics are 600 ohms to about 1K (1,000 ohms) and generate their own power. They are a lot like Speakers, they have a coil and magnet - the membrane is attached to the coil that vibrates s you talk, and the coil is suspended over the magnets poles and the coil vibrates thru the field - generating a current with a low-voltage component to it.
Electrets are 1K (1,000 ohms) or higher and require the radio to supply the power or have a battery to get their source of power from. And most FET amps use less an 5 VDC and require an Source Resistor from the Power (or Impedance) of about 2.2K (2,200 Ohms) on up to 5.6K (5,600 Ohms) to properly develop a signal that can pass thru the power source into a Blocking cap and what appears at the output - is your audio signal minus the bias power used for the FET amp in the electret.
Dynamic can be considered more of a Current Sourcing device having a low-voltage component and Electrets are more Voltage Sourcing with little current available - component.
Hope this helps drain some of the muck...
Still clear as mud right?
The above is very - very basic but I hope it helps you more in understanding that Loud is not always better...
