The 6KD6 is described as a Compactron beam pentode but we would call it a beam tetrode. The design purpose was as a line output valve in colour televisions and thus it is a substantial valve. The anode dissipation is 33 Watts and the maximum positive peak anode voltage is 7,000 Volts. The cathode current is 400 mA with a peak of 1.4 Amps.
The Toshiba logo and Made in Japan.
The large pressed anode has heat radiating side fins, the control grid is wound on copper supports and the control grid is also fitted with heat dissipating fins. The cathode is a wide rectangle.
The wide glass tube envelope is 38 mm in diameter, and excluding the B12C base pins is 104 mm tall.
Reference: Datasheet. Type 6KD6 was first introduced in 1967.