Portland is 9 hours behind Hamburg
Best overlap: 5:00 PM to 6:00 PM in Hamburg is 8:00 AM to 9:00 AM in Portland.
The overlap falls at 5:00 PM to 6:00 PM in Hamburg, or 8:00 AM to 9:00 AM if you're in Portland. There's roughly 1 hour to share, so keep agendas lean and meet at 5:00 PM in Hamburg (8:00 AM in Portland) to use every minute.