Partyline: Wireless Intercom and the TW-12C Isolation fix using the PK-7

Question: I have to galvanically isolate anexisting Clear-Com line which goes into a operation (surgery) room in ahospital. (The Clear-Com power supply is outside the surgery room and itis not allowed to introduce the Clear-Com line ground into the surgeryroom). I probably could use a TW-12C inthe surgery room which provides the beltpack power. Question: on the TW-12C - Is XLRpin 1 from "System 1" galvanically (DC-) isolated from XLR pin 1 from"System 2"? Provided, I use a WBS-670 in thesurgery room: Would an MT-1 suffice between existing Clear-Com line andWBS-670 to isolate the Clear-Com line's ground from WBS-670 Ground?

Answer: The TW-12C is designed to isolate the DC between two competing systems..  it's the ideal hum eliminator by solving the problem (s) of shifting ground potentials and ground loops. A ground loop exits when is a system which connects circuits designed to be at the same potential are actually at different potentials. It can be hazardous and cause hum.  
The WBS wireless base when connected to the Clear-Com wired base may induce a hum.as stated above.  The wireless base is connected to the mains in one part of a building and the wired base at another point... perhaps not even the same building.  For the Wireless base to operate properly, it needs to see +30 Vdc and a termination of 200 Ohms.    --- but not the feed from the wired system..    By using the PK-7 Clear-Com power supply at the wireless position, the WBS base will have its voltage and the required termination.   The TW-12C will allow the audio to pass in both directions on one Channel but isolate the ground and voltage.. No hums, no buzz -- no problems ---