(1) Tested Coronado Type 27 Tube with Engraved Base Date Code Y 27 Tube Triode

(1) Tested Sylvania 6CU8 Tube with Box Date Code am YAD Triode Pentode Tube

(1) Tested Sylvania Type 27 Tube Date Code 13R Medium Mu Triode Tube

(1) Tested National Union Type 27 Tube with Engraved Base Code J Triode Tube

(1) Tested Delco Type 27 Tube Date Code A8 Medium Mu Triode 27 Tube

(1) Tested Sylvania 6BX7GT Tube Date Code ii YKD Twin Triode Tube Black Plates

(1) Tested Sylvania 5CL8A Tube Date Code da AGD Medium Mu Triode Sharp Tetrode

(1) Tested Sylvania 12JN8 Tube with Box Date Code ZAB Triode Pentode Tube