This is a common AL4 on an European B6 6-Pin base. Designed to replace older output tubes like the E463 in older sets with the purpose to enhance performance. The cathode resister should be 150 Ohms, and in the wire to the grid a resistor of 400 Ohm should be added to prevent oscillation. The tube was made by Thermion in the Netherlands. See data taken fram Thermion nieuws of Sept-Oct 1937.
