Is the 6AC7 a lot like an octal based 6AK5? Then there's the 717A which seems to be a 6AK5 packaged in an octal base. Jim W6JVE --- "Ya can argue all ya wanna, but it's dif'rent than it was." "No it ain't! No it ain't! But ya gotta know the territory." Meredith Willson, The Music Man