Our Standard Horizon GxX150 now gets GPS data from the Q7000619A antenna.
From Standard Horizon tech support:
"Press and hold Menu for 2 seconds. Go into the General Setup. Scroll down and select NMEA Data In/Out. Make sure 4800 is highlighted"
So this was news to us. We changed this from 3800 to 4800 and we got data. Now we will need to change the settings on the Garmin 740 chart plotter to get AIS data. So happy days with no more alarm!