▼ Menu

2D4A

Sensibly equivalent to:
A20B D41 DDL4 TB24 V914
See also:
Mullard AC Mains Valves - Mullard 2D4A or Philips KB2
    
Extras ▼

 

The 2D4A valve houses a pair of signal diodes with a common cathode. The valve design is from 1934 and the diodes would have been used for demodulation at, probably at around 455 - 500 kHz, the IF frequency of broadcast radio receivers.
The 2D4B has the same electrical characteristics but is on a B7 base and has the greater versatility of separate cathodes.
This specimen is interesting because certain details of the base cap make us suspect that this valve was made at the Philips factory in Eindhoven (Holland) and imported. Probably only the 'Mullard' marking is 'British Made'. This would apparently contradict the terms of the BVA Cartel agreement which enabled Philips to exploit the British domestic market via the Mullard subsidiary.
The classic envelope is 30 mm in diameter and excluding, the B5 base pins, is 75 mm tall.
References: Datasheet & 1043. Type 2D4A was first introduced in 1934.

 

Pin Connections
B5
1
2
3
4
5
a(1)
a(2)
h
h
k

 

Absolute Maximum Operating Conditions
Diode
Vh
Ah
Va
mAa
4.0
0.65
200
0.8
PDF scanned from an original document held by the museum
Updated December29, 2012.
Return to Main Index