Vacuum Tube - 25L6GT / 25W6, Beam Power Amplifier, Tubular Glass
New-Old-Stock (NOS) tube.
Also known by US military identifier VT-201C.
The 25L6Gt is a beam pentode designed for use in the audio-frequency power output stage of radio and television receivers. Features include high power sensitivity and high efficiency at relatively low plate and screen voltages.
The 12L6GT, 25L6GT, and 50L6GT are alike except for heater ratings and heater-cathode voltage ratings.