Here's a simple recipe I've used for about 25 years with good results.
1 1/2-2 lbs pound very lean beef trimmed of all visible fat. Round steak, flank steak and eye of round work well for jerky. (If the meat is slightly frozen it will be much easier to cut into uniform strips)
1/4 to 1/2 teaspoon pepper according to taste
1/4 teaspoon onion powder
1/4 teaspoon garlic powder
1/2 teaspoon salt
1/4 cup lite soy sauce
1/4 cup liquid smoke
1/2 teaspoon Worcestershire Sauce
Mix dry ingredients with soy sauce, liquid smoke, and Worcestershire - blend well.
Cut slightly frozen beef into 1/4" thick strips.
Place the strips of meat along with the marinade mix into a large, 1-gallon plastic zip-top bag and move around to evenly distribute all of the ingredients. Place the bag into the refrigerator for 6-8 hours. (turn bag over at about 3 hrs)
pre-heat oven to 160-170 degrees for 30 minutes. (on my oven that's midway between warm and 200)
Lay strips on the oven racks and start checking the consistency of the meat after 6 hrs. Cooking times can vary quite a bit from oven to oven but it usually takes between 6 and 10 hrs.
Oh yeah, don't forget to make a foil pan for the bottom of the oven to catch the drippings - it could save you from a severe tongue lashing from the wife. (I know, I learned the hard way many years ago.

)