OK so i built a wooden electric cabinet smoker at home. It is 42" tall 26" wide and 18" deep with a 1800 watt double burner hot plate in it. Empty it gets to 150 at the top but as soon as I put the first layer of jerky in it the heat stops there, and will burly make it to 135-140 at the top. then burns that layer of jerky.(jerky strips are 1/2" apart no closer) What do I need to do to get more heat and air to move past the first layer of jerky.