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DER

Sensibly equivalent to:
POVT33
See also:
DER Valves - The Dawn of Broadcasting in the UK - Marconi DER Advert - Marconi R & DER Advert - Marconi DER Advert - Marconi DER Advert
    
Extras ▼

 

The Marconi-Osram Valve company produced the first dull emitter valves in 1921. The gold-pink envelope is characteristic of phosphorus gettering.
Markings on the envelope indicate that it was a dull emitter R-type, and that it was produced as part of the BBC consortium.
The internal construction clearly follows the pattern of the early R-type valves. The amplification factor was 9 for the DER, the same as for the R-type.
The balloon envelope is 43 mm in diameter and, excluding the B4 base pins, is 98 mm tall.
Reference: 1003. Type DER was first introduced in 1921. See also 1921 adverts.

 

Pin Connections
B4
1
2
3
4
a
g1
f
f

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
μ
1.8
0.35
80
-3
-
32,000
0.28
9.0
Updated November 16, 2016.
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