The 40KD6 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 xKD6 came in three heater variants 6KD6, 30KD6 and the 40KD6. The first was for parallel heater connections in commercial apparatus and the latter two were for sets without mains transformers and series heater chains for domestic appliances. Functionally they are equivalent.
The NEC logo.
Within the substantial anode can be seen the two grids. These are shaped to pass flat across the cathode. Also visible on the right within the anode is one beam plate.
The tops of the copper control grid supports are fitted with radiating fins.
The wide glass tube envelope is 38 mm in diameter and, excluding the B12C base pins, is 106 mm tall.
References: Data-sheet & Data. Type 40KD6 was first introduced in 1967. See also1967 adverts.
