The Crown CM-311AE or CM-312AE headworn mic works with Sennheiser's new Evolution G2 transmitter. You'll need to solder a 3.5mm (mini) stereo phone plug to the end of the mic cable, ideally using a locking phone plug from Sennheiser. Solder the mic-cable red lead to tip, white to ring, and shield to sleeve. Use the transmitter's menu to change the sensitivity from 30 dB to 0 dB. The mic will work dependably for at least 10 hours without changing batteries.
The transmitter's battery life can be extended if you modify the transmitter’s electronics. Sennheiser supplied a diagram that shows how to do it:
If the signal level is too low, Sennheiser has suggested wiring the white and red leads to the phone-plug tip. However, the EQ circuit that is inline with the cable does not work with that wiring. To get a higher output signal, you could cut off the EQ circuit, then solder the white and red leads to tip. Then the bass will be very weak. You will need to turn up the bass (low frequencies) on your mixer EQ to compensate. That might be an acceptable solution.