Vacuum Tube - 6SQ7, Diode, Dual Triode
New-Old-Stock (NOS) tube.
Also known by US military identifier VT-103.
The 6SQ7 is a metal duplex-diode high-mu triode. It is intended primarily for use as a combined detector, amplifier, and automatic-volume-control tube in radio receivers. The triode section incorporates a high amplification factor and is capable of providing a relatively large undistorted output voltage from a very small input signal.