I made a "simple" but VERY EFFECTIVE one, using a 9-pin tube sheld, stuffed with cotton wool. The "heater" was a biasing resistor (from a VR circuit) inside the can, and after about 10 minutes or less, the xtal didn't drift at all, or at least so imperceptably that I didnt' notice. Obviously, this a "crude" method, but it sure did work. Tom - WØEAJ