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W21

Sensibly equivalent to:
210VPT CV171 CV3804
See also:
CV171 short entry
    
Extras ▼

 

The W21 is a variable-mu amplifier pentode with a 2 Volt filament. It was made in two versions, this with a B4 base cap and a B7 based W21 version, both were released in 1937.
The filament is for accumulator use and the anode is designed for dry battery operation with a maximum anode voltage of 150 Volts. The operating conditions shown are for the near equivalent.
The reverse holds the marconi logo and in the image can be seen the wire loop that makes electrical connection with the external zinc paint.
The balloon envelope is 42 mm in diameter, and excluding the B4 base pins is 103 mm tall.
References: Datasheet, 1040 & 1043. Type W21 was first introduced in 1937.

 

Pin Connections
B4
1
2
3
4
tc
g2
f
g1
f
a

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
2.0
0.18
150
90
0
2.5
0.5
1.4
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated April 05, 2015.
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