(1) Tested Strong Sylvania 6CY5 Tube with Box Date Code GK BDT Tetrode Tube

(1) Tested Very Strong Sylvania Export 12ED5 Tube with Box Date Code RAE (b)

(1) Tested Sylvania 3BY6 Tube with Box Date Code CB Pentagrid Amplifier Tube (a)

(1) Tested Sylvania 6Z10 Tube with Box Date Code NR ENC Power Pentode Tube

(1) Tested Sylvania 6BJ8 Tube with Box Date Code NR KAB Canada Twin Diode Triode

(1) Tested Sylvania 12EG6 Tube with Box Date Code NR YAU Heptode Tube (a)

(1) Tested Sylvania 3BY6 Tube with Box Date Code CB Pentagrid Amplifier Tube (b)

(1) Tested Sylvania 12EG6 Tube and Box Date Code NR YAU Pentagrid Heptode (c)