hello there i have made a lot of jerky now in my manual 4 racks (Bradley) ,and actually i run 3 of them at a time usually when I'm doing my jerky.what i do and works for me is ,first off i have all three in a smoke box to start with as i call it ,just to keep the wind away and even then this smoke box is inside another building which also helps with keeping outside heat around.
then i take the morning I'm gonna go and smoke and preheat @160 and at this time do another inspection on my smoker cleaning what ever else might have to be touched up . but hey I'll preheat with out smoke for sometimes an hour or two even while i load my racks.
Then once loaded i carry all racks and meat down to the smoker and load one smoker at a time until i am done then i add my smoke pucks. when doing this i do a few things different as compared to some because i have the brick in the bottom ,no tinfoil on it,and then i use a larger tray and i do not use water in there at all.
the amount of pucks i add pucks are enough to smoke for 2- 2 1/2 hours. and i keep my top vent open usually 1/4-1/3 the way open just enough so i can stick the end of my finger in it a bit.
then i usually smoke/cook for around 3 1/2- 4 1/2 hours and then im done .i do not open the door at all to help save and keep heat in there. but once done i turn all heat off then unload meat in to my tub right there and carry to the house and let cool down even before i try it . and from there i usually have good luck with it .
i hope this helps you out some ,in case your wondering i usually do my smoking the winter time and it is cold.