For sale 2 tubes VT-231 (6sn7) Sylvania bad boys 

black plate

external welded 

silver foil getter botton 

black base 

clear glass 

tested strong on tube tester TV7D/U 

test tube 1= 98 & 100

test tube 2= 112 & 116 

reference good at 50 & 50 

reference 100% = 80 & 80 

top tubes strong performance , rare tubes 

box 196

pair 13