This adapter is used to correct powering and noise issues that can occur when measurement microphones are used with Lectrosonics UH and HM Series plug-on transmitters. This adapter may be needed if you are experiencing noise or distortion with measurement microphones, particularly the Earthworks M30.
The design includes a trifilar common mode choke wound on a ferrite bead to prevent RF from getting into the microphone capsule. XLR pins 2 and 3 are wired with reverse polarity at the output to correct for asymmetrical current draw in some P48 powered condenser microphones, including older Neumann 100 Series, Rode NTG3 and others.