It might be a good idea to get a jewelers Phillips driver and CAREFULLY take apart the Mic Plug connector and see if you have 3-wire or 4-wire - my guess is they may have inadvertently swapped shield and RX.
Shield needs to be pin 1 -and also in the handset - that shield needs to be the Audio Return and or the battery NEGATIVE for proper shielding.
Pin 4 is what pin 1 SHORTS to in RX mode, but OPENS in TX mode - with aspect to Pin 1.
Pin 1 is ground shield for everything in the mic itself - single source ground.
Don't believe me - open the things up and compare!
:+> Andy <+:
Shield needs to be pin 1 -and also in the handset - that shield needs to be the Audio Return and or the battery NEGATIVE for proper shielding.
Pin 4 is what pin 1 SHORTS to in RX mode, but OPENS in TX mode - with aspect to Pin 1.
Pin 1 is ground shield for everything in the mic itself - single source ground.
Don't believe me - open the things up and compare!
:+> Andy <+: