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4033A

Sensibly equivalent to:
3B/102B CV84 CV1220 NT37
    
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The 4033A is an interesting valve with the electrodes inclined at 45 degrees and it was used in telephone repeaters. It was the professional version of the PA1. The valve was introduced in the mid 1930s but was difficult to mass produce and was black-listed from use in military or essential commercial equipment in WWII.
The complexity of the design can be seen better in CV1220.
The 4033A has an anode dissipation of 25 Watts and can be used to 10 MHZ with reduce ratings. As an audio valve in single end configuration with a 7,000 Ω load and 400 Volts on the anode it will generate 4 Watts with low distortion.
The balloon envelope is 52 mm in diameter and, excluding the B5 base pins, is 103 mm tall.
References: Datasheet & private communication.

 

Pin Connections
B5
1
2
3
4
5
h
a
g1
c
h

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
μ
6.0
1.4
600
-20
170
1,670
9.0
15
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated August 21, 2017.
shape:balloon construction:pinch type:triode age:1930.1940 base:b5 heater:6.0v pins:5 pin:1.h pin:2.a pin:3.g1 pin:4.c pin:5.h
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