I recently got a L'Equip food dehydrator and have had some good success playing around with it. But I'm interested to know if I can dehydrate different food stuffs at the same time. For instance, could I throw jerky on one tray, onions on another, and strawberries on a third (assuming they all wanted the same time / temp) or would my strawberries end up tasting a bit like oniony beef? What kind of things would cause this contamination?
They would totally end up tasting like oniony beef! In fact your whole kitchen does- that's part of the magic of making jerky.
I can't think of a way to prevent this as the whole idea of dehydrating is to pull water out of the food and blow it away into the air.
If the flavors are compatible (or milder, like fruit) I have done different things together at once. If they don't take the same amount of time, I'll just take the done items off earlier when I check it.
Aside from flavour issues, different types of food need to be dehydrated at different temperatures and for different amounts of time. The booklet that came with my dehydrator listed suggested times/temps for various foods. You could probably mix similar items (e.g. different berries), but I definitely wouldn't mix anything like you suggest.