To collect the drippings, place a large drip pan filled with a liter of water, beer, wine, or juice underneath the turkey while it is cooking. You will want to make sure that they turkey is not sitting in the pan, you can put the pan below the grate or use a roast holder for the turkey.
If you don’t add water, the dripping with become too dry and crispy to use.
Then add the drippings to the gravy after the turkey has come off the grill. It will provide an excellent flavor boost!