These tubes are some of the earliest 12AU7s made. Kentucky Radio, Ken-Rad, made this particular version from the late 1940s to the early 1950s. General Electric liked them so much that they bought the company.
Tubes have long shiny gray ladder plates and “D” getters. The minimum GOOD reading on my Sencore tester is 70. For some reason, 12AU7 tubes test about 10 points lower than other types. Tubes were negative for shorts and grid leakage, and passed the life test. I do not know the scale or tester used by the previous owner.
Tube 1 has partial Ken-Rad logo and 0-52 (last week of 1950) date code. Emissions test 83/82 on my Sencore. Previous owner test results of 3100/3000 written on top of tube.
Tube 2 has partial GE logo and 1-13 (13th week of 1951) date code. Emissions test 81/83 on my Sencore. Previous owner test results of 3200/3000 written on top of tube.
Tube 3 has no logo remaining. Emissions test 81/80 on my Sencore. Previous owner test results of 2900/2800 written on top of tube.
Asking price is $60. Payment by PayPal. Add $3 for USPS 1st Class or $5 for USPS Priority Mail to USA.
