Vacuum Tube - 75, Dual Diode, Triode, ST Glass
New-Old-Stock (NOS) tube.
Also known by US military identifier VT-75.
The 75 is a heater-cathode type duplex-diode high-mu triode designed for use as a combined detector, audio-frequency amplifier and automatic-volume-control tube. Except for capacitances the electrical characteristics of the 75 are the same as those of the 6SQ7 and 6SQ7GT.