NMEA output from Montana 700 on AMPS mount

I have been unable to see any NMEA messages on the data output of a Montana 700 in an AMPS mount.

I have tried various settings on the Advanced NMEA setup screen (such as baud rate and GSV messages).

The Garmin Textout and Garmin Serial interfaces work ok with the same setup so the hardware and wiring

should be working correctly - there are just no NMEA messages.

Has anyone had success with NMEA o/p ? Is there anything that I might be doing wrong?

Regards

David Owen