The DE.34LF is as the name suggests a dull emitter audio voltage amplifier triode. The design dates to 1925.
The etched reversed lettering is RADION and Suitable for Repair.
The paper label around the base cap gives basic operating details.
For use with a 2.0 Volt accumulator a 5 Ω series resistor is required. The use is given as a detector and AF amplifier.
The rest of the paper band.
The base cap has the BTH logo in the centre.
The pins are of the two part type with the copper wires soldered to the top on the inner.
The vertical anode cylinder with helical control grid and single strand filament. The filament is held in a fold of the support and looks to be thoriated tungsten rather than oxide coated.
A closer view.
The balloon envelope is 35 mm in diameter and, excluding the B4 base pins, is 87 mm tall.
References: Data & 1043. Type DE.34LF was first introduced in 1925. See also1925 adverts.
