Our Four place intercom is packed with features only found in much more expensive units.
Failsafe feature for pilot in the event of power loss
Pilot isolate switch
Oprates on one 9 volt battery
Adjustable squelch (mute)
Voice activated (VOX)
Built in push to talk switch
Music in / Record out jacks
My pilot and copilot side headphones and mike work fine in my Cessna 177. The rear system does not work, can this unit be used to plug in the rear two and the copilot and would all four communicate with each other?
No, you cannot run two intercoms and have them work together. A portable intercom is intended to override the panel mount intercom. Your best bet is to buy a four place intercom and have everyone in the cabin plug into it and plug the intercom into the pilot side panel jacks.
For the Nav-Data 4 place intercom, can 4 headsets be plugged in and communicate with each other without push to talk switches?
Yes, you would not need any additional components to communicate with 3 other headsets aside from the 9v battery to power it.