Matched Pair General Electric GE 12SN7 12SN7GT Vacuum Tubes NOS NIB

Matched Pair General Electric GE 12SN7 12SN7GT Vacuum Tubes NOS NIBThis matched pair of new old stock, new in box (for Tube Two) GE 12SN7GT dual triodes was tested on our Jackson 648 Mutual Conductance tester for shorts, gas, microphonics and transconductance. There were no shorts or gas. Transconductance measured 112% 114% for Tube One and 114% 115% for Tube Two. (New 6SN7s typically test from 2600 micromhos and the Jackson expresses this in terms of a percentage.) These tubes have lyre shaped getters; short bases;

Transconductance measured 4100/3400 micromhos

9 milliamps

5 out of 10

These five US-made 12A8GT tubes were tested for shorts

This new old stock-testing

These tubes have dark-gray

but with some wear

Transconductance readings are indicated on the tops of the tubes

Tube Two (triode): 40

They measured 28/30

Tube One measured 17

It has a sheet getter