D.E.R. Marconi Osram MO-V top pip – BTH British Thompson Houston B5

Description

This section shows a pair of BTH type B5 and two pairs of Marconi-Osram type D.E.R.

D.E.R Top pip metal base

D.E.R. Top pip black base

Both valves are the same. D.E.R. Dull Emitter Receiving is a triode with thoriated filament

The BTH type B5 is a general-purpose triode produced fron 1923.