(1) Tested GE 6CU8 Tube and Box Date Code EZ General Electric Triode Pentode (b)

(1) Tested Sylvania 6CU8 Tube and Box Code am YAD Triode Pentode Vacuum Tube (b)

(1) Tested GE 6CU8 Tube with Box Code EZ General Electric Triode Pentode (a)

(1) Tested GE 6CU8 Tube with Box Date Code LW General Electric Triode Pentode

(1) Tested GE 5X8 Tube with Box Date Code FV General Electric Triode Pentode

(1) Tested RCA 6CX8 Tube with Box Date Code CR Medium Mu Triode Pentode Tube

(1) Tested GE 6JV8 Tube and Box Date Code NJ General Electric Triode Pentode (b)

(1) Tested RCA 6JV8 Tube and Box Date Code BZ Triode Pentode Tube (b)