CK722? Yup, and the 2N107, 2N35, 2N170 ? Far as I know the general design equations for transistor circuits apply more or less equally to Ge and Si, with the significant dif being the Vbe (.3 - .4 Si, .6 - .7 Ge). The Transistor Electronics book by Basil M Taraleshkov (Northrop) has a lot of specific info. John WB6BLV at inreach.com