This Osram DE6 dull emitter battery triode design dates from 1925.This exhibit carries the number two BBC stamp and that places the date of manufacture between September 1924 and 1927. Our other DE6 has a cylindrical anode and the construction follows the pattern of the original R type valves. This valve has a flattened anode and two vertical filament threads. The filament current was determined on test. The bright glow when heated indicates a thoriated tungsten filament.
The base pins are of two part construction with the lead-out wires soldered to the top of the pins.
The Osram logo is etched into the envelope. On the moulded base is the M-OV identification.
The BBC stamp, DE6 and 1.8 Volt filament voltage.
The balloon envelope is 55 mm in diameter and, excluding the B4 base pins, is 104 mm tall.
References: 4051 & 1003 Type DE6 was first introduced in 1924. See also1924 adverts.