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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
    
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The DER triode design rom Marconi dates from 1921. The filament is thoriated tungsten and so emission is achieved at a lower temperature than with pure tungsten, hence the description dull emitter. The construction is of a cylindrical anode with a helical grid passing through it, that in turn is threaded by the filament.
The balloon envelope is 43 mm in diameter and, excluding the B4 pins, is 80 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 May 16, 2015.
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