Tested Matched Pair of Philco 12SN7GTA Tubes.
Date Codes BAC.
Tubes have identical date codes and internal structure. One has a bit more getter flashing on the top than the other.
Black angled T plates with top O ring halo getters.
Tested on a calibrated Hickok TV-10 military tube tester with no shorts and no leaks with the following results:
Gm Test = 2625-2875 and 3000-2625 micromhos
Minimum pass/good = 1650-1650
Further tested under real operating conditions on a Class A amplifier and exhibiting no microphonics.
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