If anyone is interested in beef or deer jerky I use a food dehydrator and an old family recipe of ours that I would be happy to share. Usually I use it to make deer jerky but I've definitely used beef roasts in the past to make jerky.
8 Tbs Soy Sauce
8 Tbs Worcestershire Sauce
2 Tbs Ketchup
1 tsp salt
1/2 tsp garlic powder
1/2 tsp onion powder
1/2 tsp pepper
Mix these ingredients in a gallon ziploc bag and put in your sliced meat. I just eye ball everything but if I had to guess I use somewhere between a 1.5 to 2 lbs of meat per batch. Just make sure you've got enough marinade to cover all the meat. At minimum, marinate for 2 hours in the fridge, 1 hour per side. Dehydrate 8 to 10 hours.
Typically I end up leaving it in the fridge over night, will flip it in the morning, and then put it in the dehydrator when I get home from work or, if its too late, I will let it dehydrate overnight and it will be ready in the morning. It doesn't really hurt to marinate it over night. This makes more traditional jerky rather than the really soft store bought stuff. I actually have a batch going now and can take pictures if anyone desires.