The DA42 is an indirectly heated audio power triode with an anode dissipation of 40 Watts. It was designed for use as a push-pull pair in Class B to give 175 Watts out with 1kV on the anodes. The earlier DA41 has a directly heated thoriated tungsten filament and carbon anode.
The DA42 is a posr-war re-design of the DA41 using modern materials and manufacturing techniques.
This exhibit is new and came in a plain cardboard box. The valve was held by a shaped inner of the same shape as for L610 but larger.
Vyse says the anode was carbon but our exhibit clearly has a carburised metal anode.
The box anode looking along the grid plane. To the left and right are heat dissipating fins.
The Osram branding and the anode side fins.
Looking up into the anode the flat cathode and grid can be seen.
The classic envelope is 51 mm in diameter, and excluding the UX4 base pins is 131 mm tall.
References: Datasheet & 1005. Type DA42 was first introduced in 1956.