Thanks for that link to Skygeek, but the description of part # USA PA-87H is confusing.
In the title is says will convert a high impedance mic (Lightspeed Zulu for example) to use in a low impedance aircraft. But when you click on "view details" it says:
Allows military low impedance headsets equipped with U174/U plug to be used in high impedance GA helicopter (Battery powered)
Completely opposite.......