I have 2 hds gen 3 networked , 9 on bow , 12 on console , external antenna on the stern,
I need to check the 9 to make sure it is using it's own internal antenna , not the external . It appears that some
of my recent waypoints are 20 ft off ( which would happen if I marked the waypoint on the bow unit , but it is
using the rear antenna)

Help ?

thanks
Mo

Here is how to step through telling your unit to key in on anything that may be connected via NMEA on your boat.

PAGES - SETTINGS - NETWORKING - select third one down (forget exactly what it is called) - GPS - SELECT the option you want from the Drop Down list you will see for each device

Sending Private Message with phone number as I can walk you through the steps if you are in front of your unit.