Sensibly equivalent¶ to:
The Mazda HL41DD is a mains operated double diode triode for use in superhet receivers as detector, AGC rectifier and first audio voltage amplifier. The HL41 is a single triode.
The four Volt heater was the UK standard for indirectly heated AC valves in the 1930s.
The reverse is plain metallic paint.
The classic envelope is 32 mm in diameter, and excluding the base pins is 89 mm tall.
References: Datasheet, 1040 & 1043. Type HL41DD was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated March 20, 2017. shape:classic construction:pinch type:double.diode.triode age:1930.1940 base:mo heater:4.0v pins:8 pin:1.h pin:2.k pin:3.a pin:4.- pin:5.a(d2) pin:6.m pin:7.a(d1) pin:8.h pin:tc.g1