How me do it..

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First :

• i scan the drawing then open it on the AI  and the the logo look like that

• i start with the base, select the ellipse tool from the rectangle tool group in the tools panel. click on the art board. type 6 in into the width field and 4 in into the height field.
• for the next shape. doing the same but minimize the size to 3 in into the width and 2 in into the height field. and put them together like the picture.