Here are all the notes you will ever want to read, and then there are more. The first link is back in 2007 and has great info, the rest just show more detail. I bought the WW special and made a "control box" that controls the voltage...and the temp. If you can get the one with the temp control built in do it...otherwise, you can regulate the ronco convection type like mine.... ;)
http://www.modelcarsmag.com/forums/index.php?showtopic=7304&st=0&p=51109&hl=dehydrator&fromsearch=1&#entry51109
http://www.modelcarsmag.com/forums/index.php?showtopic=18901&st=0&p=165404&hl=dehydrator&fromsearch=1&#entry165404
http://www.modelcarsmag.com/forums/index.php?showtopic=34471&st=0&p=350346&hl=dehydrator&fromsearch=1&#entry350346