Philco 45 triode - matched pair, engraved base

The National Union 45 triode tubes in this precisely matched pair have ST bottles, black plates, and bottom dish getters. Both tubes test as new and are matched for both current draw (33.6 mA & 36.4 mA) and transconductance (109% Gm & 116% Gm).

The National Union 45 triode tubes in this precisely matched pair have ST bottles, black plates, and bottom dish getters. Both tubes test good and are matched for both current draw (20.5 mA & 20.5 mA) and transconductance (75% Gm & 80% Gm).

The 1940s Raytheon 45 triode tubes in this premium matched pair have ST bottles, black plates, and bottom dish getters. Both tubes test as new and they are matched for both current draw (37.0 mA & 39.8 mA) and transconductance (115% Gm & 120% Gm).