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ARD2 / D1 / CV1078 / VR78 / 10E/11540 diode

D1 size The valve measures 46x11mm overall, including pins.


Designed for TV use, D1s were used in parallel as the switches in the duplexing system of Type 79B, and subsequently Type 281 radars. They were also used in receivers at up to 100MHz.

In 1937, the Mazda D1 was the world's first miniature valve with an indirectly heated cathode. It was the basis for the EA50 (see also VR92).

Heater voltage 4.0V
Heater current 200mA
Max peak anode current 50mA
Max mean anode current 5mA
Max PIV 350V
Max heater/cathode voltage (cathode +ve to heater) 300V
Max heater/cathode voltage (cathode -ve to heater) 75V
Cac 1.35pF
Cah 0.45pF
Chc 2.4pF


Pin Function
1 Heater
2 Cathode
3 Heater
Top lead Anode



D1 VR78 ARD2

This file was last modified 15:07:41, Tuesday September 02, 2014