"The Eimac data sheet does not confirm that http://www.r-type.org/pdfs/4x150a.pdf The RCA 4X150A/7034 data does: http://pdf1.alldatasheet.com/datasheet-pdf/view/241849/ETC/7034-4X150A.html" The RCA data sheet refers to a 4X150A only, which is a different tube than the 4X150A/7034. 73, Colin K7FM