Vacuum Tube - 6SN7GT(A / B), Triode, Dual, Medium MU
New-Old-Stock (NOS) tube.
Also known by US military identifier VT-231.
The 6SN7GTB is a medium-mu twin triode suitable for use in a wide variety of general-purpose amplifier and phase-inverter applications. It is also especially useful as a blocking oscillator, multivibrator, or vertical deflection amplifier in television receivers.