Sensibly equivalent¶ to:
The A1820 is a wideband video amplifier tetrode. The maximum anode dissipation is 10 W. The CV direct equivalent is the CV409.
Although introduced in America in the late 1930's it is believed that it was not made in the UK until the late 1940's or early 1950's.
The internal construction is obscured by the graphite coating inside the envelope.
The B8B or Loctal base. The spigot pushes out a spring in the valve holder and the spring drops into the groove thus holding the valve securely in its socket.
The wide glass tube envelope is 31 mm in diameter, and excluding the B8B base pins is 69 mm tall.
References: 3002. Type A1820 was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated November 21, 2012. shape:wide.glass.tube construction:all.glass type:tetrode age:1930.1940 base:b8b heater:6.3v pins:8 pin:1.h pin:2.a pin:3.g2 pin:4.s pin:5.s pin:6.g1 pin:7.k pin:8.h