pilot pa400 with king 170
 

Hi all.
I have a piper tomahawk wich has a single Nav/Comm, a king 170. The aircraft has no intercom or audio panel.
I recently bought a Pilot PA 400 external intercom that plugs into the existing panel sockets.

When testing the unit at home I found it work exactly as I wanted it to, with the squelch operating.
When i ffited it into the aircraft and turrned the radio on, I found that the squelch seemed to stick open and I could hear everything despite the squelch light not being on on the intercom.
Conclusion:- The intercom makes no difference at all!
Any help??
Jon