The Cossor 61BT is a beam tetrode for television line scan output. This valve would have been used in post war monochrome VHF television receivers.
The cathode bias resistor would have been of the order of 470 Ohms and the positive surge on the anode could reach 5,000 Volts. The anode dissipation was limited to 8 Watts and the screen to 1.75 Watts.
The ceramic insulators with the anode supports connected to the top cap. The supports are held in the side flanges of the anode at the point of greatest heat generation.
The flat cathode with rounded ends, insulated heater and copper g1 supports.
The classic envelope is 32 mm in diameter and, excluding the IO base pins, is 89 mm tall.
