Pair tube direct heat triode American lot: 6539/6952 double square getter measurement value 80/78 (rejection value 58) with replacement box Both tubes were burned by mica at the top of the tube head, and the getter has decreased slightly ※Pairs are judged based on the gM value measured by the testing machine TV-7 (Kojima Yosuke)
Accessories: replacement box (WE300B original box since 1995)