Hey there...This topic of "can you use a food dehydrator to dry shrooms" seems to come up a lot... search the message boards for "dehydrator" and you'll get more questions and answers on the topic than you can handle...
In short, though... yes, food dehydrators can be used to dry shrooms, just keep the heat minimal. Or, disconnect the heating element -- even better.
You still might need to let them chill in a dessicant chamber for a day or two after dehydrating to get them "cracker-dry," however.
good luck
c