as Tom said in msg#7;
"On Ancestry, maybe you will have to right-click on the "Download your GEDCOM file" button when it appears rather than left-click. Then from the popup menu select "Save link (or target) as..." and be sure that the filename includes the .ged extension."
That does work and gives the .ged extension on the downloaded GEDCOM. So it should work. I guess the OP has some other problem.
I'll delete my posts abaove...thanks,