The MH-31 delivered with some Yaesu-radio's, e.g. the FT-897, is an acoustic disaster - too bassy for "westerners"; -a very simple modification makes the mike OK.
- Take off the back-cover of the mike (3 screws).
- Loosen the three black screws and loosen the printed circuit.
- Carefully take out the mike- cartridge.
- With a VERY small soldering-iron-tip, burn a little hole in the
middle of the membrane, max 1 - 2 mm wide; start with the smallest!
Reassemble the mike! - and test it on the air.
This little mod. takes away the worst bass - on-the-air-reports indicate a dramatic improvement!
Don't blame me, if u spoil the mike - by a new cartridge!!