My 2003 Mark II tall rig/wing keel Catalina Linear Drive P70 auto pilot worked fine until I upgraded the other eletronics.  I changed the binnacle Garmin 545 to a Garmin 1040 with radar, added a Garmin thru hull depth finder, and added a Vesper Marine AIS.  Now the auto pilot works for a few minutes and then the boat starts drifting -the screen is lit and pushing direction buttons does nothing.  When I put the auto pilot on "standby"" and then back to "auto" it works fine for another few minutes.  I am thinking it may be a compass issue (I put the old 545 down below, and I also added a Garmin Heading sensor. ) I moved the 545  antenna and the Vesper antenna a few feet apart (they are both on the stern rail)  but there was no change. The Raymarine control box has a switch that was "off" and I moved it to "on" with no change.
I am on the ICW in Florida heading south and need suggestions.    I think there is a good Raymarine  dealer in Ft. Pierce but I would like to see if I can fix it-I think it is probably something simple.
Thanks
Jack
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