Tested Matched Pair of RCA 6SN7GTA Tubes.
Date Codes 713 and 509.
Tubes are closely matched for Gm testing and internal structure - they are identical.
Thin bases with silver lettering.
Black staggered plates with copper grid posts, side square D getters and clear mica spacers.
The tube number is worn off the glass on one tube.
Tested on a calibrated Hickok TV-10 military tube tester with no shorts and no leaks with the following results:
Gm Test = 2750-3000 and 3000-3000 micromhos
Minimum pass/good = 1650-1650
Further tested under real operating conditions on a Class A amplifier and exhibiting no microphonics.
~ Please view all 6 photos ~
