"Juicy" jerky will usually have some form of hygroscopic additive.... sugar, honey, phosphates etc... those additives hang onto moisture to keep the product moist... Whether you use salt, soy sauce and spices, if the moisturizing ingredients are not included, you should get the product you are looking for.... Just a note about sugar, it is used to "combat" the saltiness that can be encountered in some jerky recipes...
FWIW, when using wild game for non cooked meat products, it is advisable to freeze the meat, for about a month below zero, to kill any parasites that may be living in the meat... Freezing also ruptures the cells in the meat, and that cell rupture, helps the meat to dry...