Hi! I will erect a 15m high crank down antenna mast. I want to put a 20m Cushcraft A3S and a 3 element Yagi for 6m I would like to stack a 6m beam above a 20m beam, but can't find any data on what the mininium distance should be. Does anyone have any suggestions on where I might find some info or on what the spacing should be? Many Thanks VA6POP