Any dehydrator with a fan is good. If the morels are not wet, a low to medium heat is fine. If they are wet, like if you rinsed them, then use high heat for maybe an hour, then lower it to low/medium. Anywhere in the 100 to 125 range is good. Run until the product is cracker-snap dry.
Laid out on paper in the back dash of a car (windows cracked open) on a sunny day is a good way to dry them too. Dried morels are awesome! Good luck!