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DE5

Sensibly equivalent to:
CV2891
See also:
The Dawn of Broadcasting in the UK - Marconi DE5 Advert
    
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 base clearly carries the M-OV Co Ltd logo. We can say with certainty that M-OV were using the metal shell B4 base with the two part pins in May 1924.
The anode is just visible within the envelope. The etching of the Marconi identification is clear. the majority of the envelope has the familiar mirror of Magnesium gettering.
The size of the envelope is slightly larger in both diameter and height than later examples.
See also DE5, DE5, DE5A and DE5B
The balloon envelope is 56 mm in diameter, and excluding the B4 base pins, is 106 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
8000
0.88
PDF scanned from an original document held by the museum
Updated December03, 2012.
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