1A7GT is a glass vacuum tube used for valves and amplifiers. It is a low-mu miniature type tube, with four pins on the base, and can handle both DC and AC signals. The 1A7GT is a versatile tube, often used in audio power amplifiers, resistive dividers, rectifier circuits, and certain types of oscillators. It has a low gain of 35, which means it is suitable for circuits where high levels of amplification are not needed. Its maximum plate voltage is 250 volts, and its maximum plate current is 0.2 amps. The 1A7GT is a great tube for audio applications, as it has a good sound quality and offers great value for money.