The 3Q5GT is a battery pentode with a centre tapped filament. When the two halves are in parallel for a 1.4 Volt supply the valve is identical to the 1Q5. But the filaments in series for a 2.8 Volt supply require only 50 mA.
As an audio output valve the maximum output is 500 mW for 10% total harmonic distortion.
The bright box anode.
Side view of the anode with the filament top supports on the right. The filament tension spring can be seen arching above the top mica.
The wire grids can be seen through the top mica sheet.
The filament tension springs are to the sides of the holes in the mica so that the filament is kept in place at the points in the diamond shaped hole in the mica.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 64 mm tall.
