The VT-289 12SL7GT is a medium impedance double triode with high gain, it has separate cathodes and was designed for use as AF voltage amplifiers, phase splitters and where required as a cascade amplifier of very high gain.
The octagon feintly etched into the glass carries the Type designation 12SL7GT.
The 6SL7GT differs only in the fact that the heater is rated for 6.3 Volt operation.
The Tung-Sol name and Made in USA.
The two anodes are folded and stitched together. Above the top mica can be seen the tops of the grid supports and the cathode tube.
Top view giving the geometry of the triodes.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 62 mm tall.
