http://heilsound.com/amateur/adapters/index.phpThis page indicates that you need the CC-1-Y cable for the Omni7.
The XLR connector:
Pin-1 = shield
Pin-2 = audio
Pin-3 = audio return
For an unbalanced connection:
At the Omni7 end Pin-1, Pin-3, and the XLR ground tab should connect to the shield. Pin-2 goes to the audio. Then you also need to add a PTT switch as required.