The PV5DE is an dull emitter output triode that was introduced in 1924. The glass carries the first style of BBC stamp that was used from November 1922 until September 1924 making this exhibit an early example of the PV5DE.
The staggered lengths of the base pins were Ediswan's safety cap to prevent burning out of the filament by accidental connection across the anode circuit.
Using the microscope it was possible to image the vertical anode under the gettering.
The zig-zag wire on the left is the filament tension spring.
The BBC stamp and the Ediswan name.
The PV are clear but the rest of the Type designation failed to image clearly.
The balloon envelope is 53 mm in diameter, and excluding the B4 base pins is 98 mm tall.
References: 1003 & 1004. Type PV5DE was first introduced in 1924. See also1924 adverts.
