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DE5

Sensibly equivalent to:
CV2891
See also:
The Dawn of Broadcasting in the UK
    
Extras ▼

 

The DE5 is a dull emitter triode designed to be used as an audio output valve to drive small loud speakers.
The DE5 was introduced in May 1924 and this exhibit carries the first BBC stamp etched into the glass. This has the words Type Approved by Postmaster General around the edge. This stamp was used from 1st November 1922 until September 1924. Thus we have good reason to believe that this form of the DE5 was the first to be introduced. The valve in the advert from May 28, 1924 has a metal skirt.
The gettering only obscures half of the envelope.
The BBC stamp and in the foreground the support for the filament tensioning spring.
The anode supports are connected to the bright anode by shaped wires.
The lower filament supports and the grid wires.
The third form of the BBC stamp with Made in England around the central logo.
The base cap with the insulating insert carrying the MOV letters.
The original box.
Micrograph of the base of the filament.
With some difficulty the feint etched lettering was imaged.
The balloon envelope is 56 mm in diameter, and excluding the B4 base pins, is 108 mm tall.
References: 4051 & 1003 Type DE5 was first introduced in 1924.

 

Pin Connections
B4
1
2
3
4
a
g1
f
f

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
5.0
0.25
120
-6
5.4
8,000
0.88
PDF scanned from an original document held by the museum
Updated March 12, 2021.
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