(1) Tested Philco 6AU6 Tube.
Date Code 55-47.
The 312 EIA code indicates that tube was made by Sylvania for Philco.
The wording is partially worn but still legible.
This tube tests above NOS specs.
Tested on a calibrated Hickok TV-10 military tube tester and exhibiting no shorts or leaks with the following results:
Test Result = 3250 micromhos
Minimum pass/good = 2050
NOS Target Value = 3075
